Title of Invention

INTRACELLULAR PATHOGEN VACCINES FOR PREVENTING DISEASES IN MAMMALS .

Abstract Vaccines and immunotherapeulics for preventing intracellular pathogen diseases in mammals are provided that con- sist of recombinant attenuated intracellular pathogens that have been transformed to express recombinant immunogenic antigens of the same r other intracellular pathogens. Exemplary vaccines and immunotherapeulics include attenuated recombinant Mycobacte- ria expressing the major extracellular non-fusion proteins of Mycobacterial and/or other intracellular pathogens. These exemplary vaccines are shown to produce surprisingly potent protective immune response in mammals that surpass those of any previously known anti-mycobaclerium vaccine. More specifically, a recombinant BCG expressing the 30 kDa major extracellular non-fusion protein of Mycobacterium tubercolosis is provided. Additionally, methods for preventing and treating diseases caused by intracellu- lar pathogens are provided. The methods of treating and preventing intracellular pathogen diseases utilize the described surprisingly efficacious vaccines and immunolherapeutics.
Full Text IntracellUlar pathogen vaccines for preventing diseases in mammals
Reference to Government
This invention was made with Government support under Grant No. AI31338 awarded by
the Department of Health and Human Services. The Government has certain rights in this
invention.
Field of the Invention
The present invention generally relates to immunotherapeutic agents and vaccines against
intracellular pathogenic organisms such as bacteria, protozoa, viruses and fungi. More
specifically, unlike prior art vaccines and immunotherapeutic agents based upon pathogenic
subunits, killed pathogens and attenuated natural pathogens, the present invention uses
recombinant attenuated pathogens, or closely related species, that express and secrete
immunogenic determinants of a selected pathogen stimulating an effective immune response in
mammalian hosts. The immunostimulatory vaccines and immunotherapeutics of the present
invention are derived from recombinant attenuated intracellular pathogens, or closely related
species, that express immunogenic determinants in silv.
Background of the Invention
It has long been recognized that parasitic microorganisms possess the ability to infect
animals thereby causing disease and often the death of the host. Pathogenic agents have been a
leading cause of death throughout history and continue to inflict immense suffering. Though the
last hundred years have seen dramatic advances in the prevention and treatment of many
infectious diseases, complicated host-parasite interactions still limit the universal effectiveness of
therapeutic measures. Difficulties in countering the sophisticated invasive mechanisms displayed
by many pathogenic organisms is evidenced by the resurgence of various diseases such as
tuberculosis, as well as the appearance of numerous drug resistant strains of bacteria and viruses.
Among those pathogenic agents of major epidemiological concern, intracellular bacteria
have proven to be particularly intractable in the face of therapeutic or prophylactic measures.
Intracellular bacteria, including the genus Mycobacterium and the genus Legionella, complete all
or part of their lifecycle within the cells of the infected host organism rather than extraceilularly.
Around the world, intracellular bacteria are responsible for millions of deaths each year and untold
suffering. Tuberculosis is the leading cause of death from a single disease agent worldwide, with
10 million new cases and 2.9 million deaths every year. In addition, intracellular bacteria are
responsible for millions of cases of leprosy. Other debilitating diseases transmitted by intracellular
agents include cutaneous and visceral leishmaniasis, American trypanosomiasis (Chagas disease),
listeriosis, toxoplasmosis, histoplasmosis, trachoma, psittacosis, Q-fever, and legionellosis. At
this time, relatively little can be done to prevent debilitating infections in susceptible individuals
exposed to many of these organisms Due to this inability to effectively protect populations from
such intracellular pathogens and the resulting human and animal morbidity and mortality caused
by such agents, tuberculosis, is one of the most important diseases now confronting mankind.
Those skilled in the art will appreciate that the following exemplary discussion of M.
tuberculosis is illustrative of the teachings of the present invention and is in no way intended to
limit the scope of the present invention to the treatment of M. tuberculosis. Similarly, the
teachings herein are not limited in any way to the treatment of tubercular infections. On the
contrary, this invention may be used to advantageously provide safe and effective vaccines and
immunotherapeutic agents against any pathogenic agent by using recombinant attenuated
pathogens, or recombinant avirulent organisms, to express, and of equal importance to release the
immunologically important proteins of the pathogenic organism.
Currently it is believed that approximately one-third of the world's population is infected
by M. tuberculosis resulting in millions of cases of pulmonary tuberculosis annually. More
specifically, human pulmonary tuberculosis primarily caused by M. tuberculosis is a major cause
of death in developing countries. Capable of surviving inside macrophages and monocytes, M.
tuberculosis may produce a chronic intracellular infection. M. tuberculosis is relatively successful
in evading the normal defenses of the host organism by concealing itself within the cells primarily
responsible for the detection of foreign elements and subsequent activation of the immune system.
Moreover, many of the front-line chemotherapeutic agents used to treat tuberculosis have
relatively low activity against intracellular organisms as compared to extracellular forms. These
same pathogenic characteristics have heretofore prevented the development of fully effective
immunotherapeutic agents or vaccines against tubercular infections.
While this disease is a particularly acute health problem in the developing countries of
Latin America, Africa, and Asia, it is also becoming more prevalent in the first world. In the
United States specific populations are at increased risk, especially urban poor,
immunocompromised individuals and immigrants from areas of high disease prevalence. Largely
due to the AIDS epidemic, in recent years the incidence of tuberculosis has increased in developed
countries, often in the form of multi-drug resistant M tuberculosis.
Recently, tuberculosis resistance to one or more drugs was reported in 36 of the 50 United
States. In New York City, one-third of all cases tested was resistant to one or more major drugs.
Though non-resistant tuberculosis can be cured with a long course of antibiotics, the outlook
regarding drug resistant strains is bleak. Patients infected with strains resistant to two or more
major, antibiotics have a fatality rate of around 50%. Accordingly, safe and effective vaccines
against such varieties ofM tuberculosis are sorely needed.
Initial infections of M. tuberculosis almost always occur through the inhalation of
aerosolized particles as the pathogen can remain viable for weeks or months in moist or dry
sputum. Although the primary site of the infection is in the lungs, the organism can also cause
infection of nearly any organ including, but not limited to, the bones, spleen, kidney, meninges
and skin. Depending on the virulence of the particular strain and the resistance of the host, the
infection and corresponding damage to the tissue may be minor or extensive. In the case of
humans, the initial infection is controlled in the majority of individuals exposed to virulent strains
of the bacteria. The development of acquired immunity following the initial challenge reduces
bacterial proliferation thereby allowing lesions to heal and leaving the subject largely
asymptomatic.
When M. tuberculosis is not controlled by the infected subject it often results in the
extensive degradation of lung tissue. In susceptible individuals lesions are usually formed in the
lung as the tubercle bacilli reproduce within alveolar or pulmonary macrophages. As the
organisms multiply, they may spread through the lymphatic system to distal lymph nodes and
through the blood stream to the lung apices, bone marrow, kidney and meninges surrounding the
brain. Primarily as the result of cell-mediated hypersensitivity responses, characteristic
granulomatous lesions or tubercles are produced in proportion to the severity of the infection.
These lesions consist of epithelioid cells bordered by monocytes, lymphocytes and fibroblasts. In
most instances a lesion or tubercle eventually becomes necrotic and undergoes caseation
(conversion of affected tissues into a soft cheesy substance).
While M tuberculosis is a significant pathogen, other species of the genus Mycobacterium
also cause disease in animals including man and are clearly within the scope of the present
invention. For example, M. bovis is closely related to M. tuberculosis and is responsible for
tubercular infections in domestic animals such as cattle, pigs, sheep, horses, dogs and cats.
Further, M. bovis may infect humans via the intestinal tract, typically from the ingestion of raw
milk. The localized intestinal infection eventually spreads to the respiratory tract and is followed
shortly by the classic symptoms of tuberculosis. Another important pathogenic vector of the
genus Mycobacterium is M. leprae that causes millions of cases of the ancient disease leprosy.
Other species of this genus which cause disease in animals and man includeM kansasii, M. avium
intracellulare, M. fortuitum, M. marinum, M. chelonei, and M. scrofulaceum. The pathogenic
mycobacterial species frequently exhibit a high degree of homology in their respective DNA and
corresponding protein sequences and some species, such as M. tuberculosis and M. bovis, are
highly related.
For obvious practical and moral reasons, initial work in humans to determine the efficacy
of experimental compositions with regard to such afflictions is infeasible. Accordingly, in the
early development of any drug or vaccine it is standard procedure to employ appropriate animal
models for reasons of safety and expense. The success of implementing laboratory animal models
is predicated on the understanding that immunogenic epitopes are frequently active in different
host species. Thus, an immunogenic determinant in one species, for example a rodent or guinea
pig, will generally be immunoreactive in a different species such as in humans. Only after the
appropriate animal models are sufficiently developed will clinical trials in humans be carried out
to further demonstrate the safety and efficacy of a vaccine in man.
With regard to alveolar or pulmonary infections by M tuberculosis, the guinea pig model
closely resembles the human pathology of the disease in many respects. Accordingly, it is well
understood by those skilled in the art that it is appropriate to extrapolate the guinea pig model of
this disease to humans and other mammals. As with humans, guinea pigs are susceptible to
tubercular infection with low doses of the aerosolized human pathogen M. tuberculosis. Unlike
humans where the initial infection is usually controlled, guinea pigs consistently develop
disseminated disease upon exposure to the aerosolized pathogen, facilitating subsequent analysis.
Further, both guinea pigs and humans display cutaneous delayed-type hypersensitivity reactions
characterized by the development of a dense mononuclear cell induration or rigid area at the skin
test site. Finally, the characteristic tubercular lesions of humans and guinea pigs exhibit similar
morphology including the presence of Langhans giant cells. As guinea pigs are more susceptible
to initial infection and progression of the disease than humans, any protection conferred in
experiments using this animal model provides a strong indication that the same protective
immunity may be generated in man or other less susceptible mammals. Accordingly, for purposes
of explanation only and not for purposes of limitation, the present invention will be primarily
demonstrated in the exemplary context of guinea pigs as the mammalian host. Those skilled in
the art will appreciate that the present invention may be practiced with other mammalian hosts
including humans and domesticated animals.
Any animal or human infected with a pathogenic organism and, in particular, an
intracellular organism, presents a difficult challenge to the host immune system. While many
infectious agents may be effectively controlled by the humoral response and corresponding
production of protective antibodies, these mechanisms are primarily effective only against those
pathogens located in the body's extracellular fluid. In particular, opsonizing antibodies bind to
extracellular foreign agents thereby rendering them susceptible to phagocytosis and subsequent
intracellular killing. Yet this is not the case for other pathogens. For example, previous studies
have indicated that the humoral immune response does not appear to play a significant protective
role against infections by intracellular bacteria such as M. tuberculosis. However, the present
invention may generate a beneficial humoral response to the target pathogen and, as such, its
effectiveness is not limited to any specific component of the stimulated immune response.
More specifically, antibody mediated defenses seemingly do not prevent the initial
infection of intracellular pathogens and are ineffectual once the bacteria are sequestered within the
cells of the host. As water soluble proteins, antibodies can permeate the extracellular fluid and
blood, but have difficulty migrating across the lipid membranes of cells. Further, the production
of opsonizing antibodies against bacterial surface structures may actually assist intracellular
pathogens in entering the host cell. Accordingly, any effective prophylactic measure against
intracellular agents, such as Mycobacterium, should incorporate an aggressive cell-mediated
immune response component leading to the rapid proliferation of antigen specific lymphocytes
that activate the compromised phagocytes or cytotoxically eliminate them. However, as will be
discussed in detail below, inducing a cell-mediated immune response does not equal the induction
of protective immunity. Though cell-mediated immunity may be a prerequisite to protective
immunity, the production of vaccines in accordance with the teachings of the present invention
requires animal based challenge studies.
This cell-mediated immune response generally involves two steps. The initial step,
signaling that the cell is infected, is accomplished by special molecules (major histocompatibility
or MHC molecules) which deliver pieces of the pathogen to the surface of the cell. These MHC
molecules bind to small fragments of bacterial proteins that have been degraded within the
infected cell and present them at the surface of the cell. Their presentation to T-cells stimulates
the immune system of the host to eliminate the infected host cell or induces the host cell to
eradicate any bacteria residing within.
Attempts to eradicate tuberculosis using vaccination was initiated in 1921 after Calmette
and Guerin successfully attenuated a virulent strain of M. bovis using in vitro serial passage
techniques. The resultant live vaccine developed at the Institut Pasteur in Lille, France is known
as the Bacille Calmette and Guerin, or BCG vaccine. Nearly eighty years later this vaccine
remains the only prophylactic therapy for tuberculosis currently in use. In fact, all BCG vaccines
available today are derived from the original strain of M. bovis developed by Calmette and Guerin
at the Institut Pasteur.
The World Health Organization considers the BCG vaccine an essential factor in reducing
tuberculosis worldwide, especially in developing nations. In theory, BCG vaccine confers cell-
mediated immunity against an attenuated mycobacterium that is immunologically related to M.
tuberculosis. The resulting immune response should prevent primary tuberculosis. Thus, if
primary tuberculosis is prevented, latent infections cannot occur and disease reactivation is
avoided.
However, controlled clinical trials have revealed significant variations in vaccine efficacy.
Reported efficacy rates have varied between 0-80%. Vaccine trials conducted in English school
children reported a ten-year post vaccination protection rate in excess of 78%. However, in a
similar trial in South India, BCG failed to protect against culture-proven primary tuberculosis in
the first 5 years post inoculation. A recent meta-analysis of BCG efficacy in the prevention of
tuberculosis estimated that overall prophylactic efficacy was approximately 50%. (Colditz, G.A.
T.F. Brewer, C.S. Berkey, M.E. Wilson, E. Burdick, H.V. Fineberg, and F. Mosteller. 1994.
JAMA 271.698-702.)
This remarkable disparity in reported efficacy rates remains a vexing problem for health
officials and practitioners that must determine when and how to use the BCG vaccine. Numerous
factors have been implicated that may account for these observed efficacy disparities including
differences in manufacturing techniques, routes of inoculation and characteristics of the
populations and environments in which the vaccines have been used. Recent work suggests that
incidental contact with environmental mycobacteria may result in a "natural vaccine" that
prevents the vaccine recipient from mounting an effective response to native BCG proteins.
In order to minimize BCG immunogenicity variation, vaccine manufactures maintain
master stocks of original vaccine strains in the lyophilized (freeze-dried) state. Each production
strain derived therefrom is in turn named after the manufacturing site, company or bacterial strain,
for example: BCG-London, BCG-Copenhagen, BCG-Connaught, or BCG-Tice (marketed
worldwide by Organon, Inc.). In an effort to standardize manufacturing techniques in the United
States, the Federal Food and Drug Administration's (FDA) Center for Biologic Education and
Research (CBER) regulates vaccine manufacturing. The FDA's CBER branch has specified that
each lyophilized BCG strain used for vaccination must be capable of inducing a specified
tuberculin skin test reaction in guinea pigs and humans. Unfortunately, induced tuberculin
sensitivity has not been shown to correlate with protective immunity.
Current BCG vaccines are provided as lyphophilzed cultures that are re-hydrated with
sterile diluent immediately before administration. The BCG vaccine is given at birth, in infancy,
or in early childhood in countries that practice BCG vaccination, including developing and
developed countries. Adult visitors to endemic regions who may have been exposed to high doses
of infectious mycobacteria may receive BCG as a prophylactic providing they are skin test non-
reactiye. Adverse reactions to the vaccine are rare and are generally limited to skin ulcerations
and lymphadenitis near the injection site. However, in spite of these rare adverse reactions, the
BCG vaccine has an unparalleled history of safety with over three billion doses having been
administered Avorldwide since 1930.
Eighty-years have now passed since BCG was developed and there remains paucity in
acceptable vaccine alternatives. Recently, the present inventors have made considerable
progress in the isolation, characterization and recombinant expression of extracellular proteins
secreted by intracellular pathogens. For example, the inventors' U.S. Patent No. 5,108,745,
issued April 28, 1992 and several pending U.S. Patent applications provide vaccines and methods
of producing protective immunity against L. pneumophila and M. tuberculosis as well as other
intracellular pathogens. These prior art vaccines are broadly based on extracellular products
originally derived from proteinaceous compounds released extracellularly by the pathogenic
bacteria into broth culture in vitro and released extracellularly by bacteria within infected host
cells in vivo. As provided therein, these vaccines are selectively based on the identification of
extracellular products or their analogs that stimulate a strong immune response against the target
pathogen in a mammalian host.
Vaccines prepared from selected M. tuberculosis extracellular products are currently being
optimized for use as human prophylactic therapies. Protein cocktails and individual protein
preparations using both recombinant as well as naturally expressed proteins are being studied.
One goal of these ongoing studies is to maximize the base immune response through optimum
immunogen (protein) presentation. To date over 100 different preparations have been made
including 38 different protein combinations, 26 different adjuvants, 10 different protein
concentrations and seven different dosing regimens. The candidate vaccine proteins have also
been coupled to non-M tuberculosis proteins including bovine serum albumin, Legionella sp.
major secretory protein, and tetanus toxoid. This list is not inclusive of methods the present
inventors have used to present extracellular proteins of intracellular pathogens to host animals;
rather it illustrates the enormous complexity and inherent variability associated with vaccine
optimization. However, in spite of these and other activities, no combination of extracellular
proteins, adjuvants, carrier proteins, concentrations or dosing frequencies resulted in inducing a
protective immune response in guinea pigs that was comparable or superior to BCG.
Recently, significant attention has been focused on using transformed BCG strains to
produce vaccines that express various cell-associated antigens. For example, C.K. Stover, et
al. have reported a Lyme Disease vaccine using a recombinant BCG (rBCG) that expresses the
membrane associated lipoprotein OspA of Boirelia burgdorferi. Similarly, the same author
has also produced a rBCG vaccine expressing a pneumococcal surface protein (PsPA) of
Streptococcus pneumoniae. (Stover, C.K., G.P. Bansal, S. Langerman, and M.S. Hanson.
1994. Protective Immunity Elicited by rBCG Vaccines. In: Brown F. (ed): Recombinant
Vectors in Vaccine Development. Dev Biol Stand. Dasel, Karger, Vol. 82, 163-170.)
United States patent number (USPN) 5,504,005 (the '"005" patent") and USPN
5,854,055 (the '"055 patent") both issued to B.R. Bloom et al., disclose theoretical rBCG
vectors expressing a wide range of cell associated fusion proteins from numerous species of
microorganisms. The theoretical vectors described in these patents are either directed to cell
associated fusion proteins, as opposed to extracellular non-fusion protein antigens, and/or the
rBCG is hypothetically expressing fusion proteins from distantly related species. Moreover,
the recombinant cell associated fusion proteins expressed in these models are encoded on DNA
that is integrated into the host genome and under the control of heat shock promoters.
Consequently, the antigens expressed are fusion proteins and expression is limited to levels
approximately equal to, or less than, the vector's native proteins.
Furthermore, neither the '005 nor the '055 patent disclose animal model safety testing,
immune response development or protective immunity in an animal system that closely
emulates human disease. In addition, only theoretical rBCG vectors expressing M.
tuberculosis fusion proteins are disclosed in the '005 and '055, no actual vaccines are enabled.
Those vaccine models for M. tuberculosis that are disclosed are directed to cell associated heat
shock fusion proteins, not extracellular non-fusion proteins.
United States patent number 5,830,475 (the '"475 patent") also discloses theoretical
mycobacterial vaccines used to express "fusion proteins. The DNA encoding for these fusion
proteins resides in extrachromasomal plasmids under the control of mycobacterial heat shock
protein and stress protein promoters. The vaccines disclosed are intended to elicit immune
responses in non-human animals for the purpose of producing antibodies thereto and not shown
to prevent intracellular pathogen diseases in mammals. Moreover, the '475 patent does not
disclose recombinant vaccinating agents that use protein specific promoters to express
extracellular non-fusion proteins.
The present inventors propose, without limitation, that major extracellular non-fusion
proteins of intracellular pathogens may be important immunoprotective molecules. First,
extracellular non-fusion proteins, by virtue of their release by the pathogen into the
intracellular milieu of the host cell, are available for processing and presentation to the immune
system as fragments bound to MHC molecules on the host cell surface. These peptide-MHC
complexes serve to alert the immune system to the presence within the host cell of an otherwise
hidden invader, enabling the immune system to mount an appropriate anti-microbial attack
against the invader. Second, effective immunization with extracellular proteins is able to
induce a population of immune cells that recognize the same peptide-MHC complexes at some
future time when the complexes are displayed on host cells invaded by the relevant
intracellular pathogen. The immune cells are thus able to target the infected host cells and
either activate them with cytokines, thereby enabling them to restrict growth of the intracellular
pathogen, or lyse them, thereby denying the pathogen the intracellular milieu in which it
thrives. Third, among the extracellular proteins, the major ones, i.e., those produced most
abundantly, will figure most prominently as immunoprotective molecules since they would
generally provide the richest display of peptide-MHC complexes to the immune system.
Therefore, there remains a need for recombinant intracellular pathogen vaccines that
express major extracellular non-fusion proteins of intracellular pathogens that are closely
related to the vaccinating agent. Furthermore, there is a need for recombinant intracellular
pathogen vaccines that are capable of over-expressing recombinant extracellular non-fusion
proteins by virtue of extrachromosomal DNA having non-heat shock gene promoters or non-
stress protein gene promoters.
Specifically, there remains an urgent need to produce intracellular pathogen vaccines
that provide recipients protection from diseases that is superior to the protection afforded BCG
vaccine recipients. Moreover, there is an urgent need to provide both developed and
developing countries with a cost efficient, immunotherapeutic and prophylactic treatment for
tuberculosis and other intracellular pathogens.
Therefore, it is an object of the present invention to provide therapeutic and prophylactic
vaccines for the treatment and prevention of disease caused by intracellular pathogens.
It is another object of the present invention to provide vaccines for preventing intracellular
pathogen diseases using intracellular pathogens that have been transformed to express the major
recombinant immunogenic antigens of the same intracellular pathogen, another intracellular
pathogen, or both.
It is yet another object of the present invention to provide vaccines for the treatment and
prevention of mycobacteria diseases using recombinant BCG that expresses the extracellular
protein(s) of a pathogenic mycobacterium.
It is another object of the present invention to provide vaccines for treatment and/or
prevention of tuberculosis using recombinant strains of BCGthat express and secrete one or more
major extracellular proteins of'Mycobacterium tuberculosis.
Summary of the Invention
The present invention accomplishes the above-described and other objects by providing a
new class of vaccines and immunotherapeutics and methods for treating and preventing
intracellular pathogen diseases in mammals. Historically intracellular pathogen vaccines and
immunotherapeutics have been prepared from the intracellular pathogen itself or a closely related
species. These old vaccine models were composed of the entire microorganism or subunits
thereof. For example, the first, and currently only available vaccine, for Mycobacterium
tuberculosis is an attenuated live vaccine made from the closely related intracellular pathogen M.
bovis. Recently, the present inventors have discovered that specific extracellular products of
intracellular pathogens that are secreted into growth media can be used to illicit protective
immune responses in mammals either as individual subunits, or in subunit combinations.
However, these subunit vaccines have not proven to be superior to the original attenuated vaccine
derived fromM bovis.
The present invention details vaccines and immunotherapeutics composed of recombinant
attenuated intracellular pathogens (vaccinating agents) that have been transformed to express the
extracellular protein(s) (recombinant immunogenic antigens) of another or same intracellular
pathogen. In one embodiment the vaccines of the present invention are made using recombinant
strains of the Bacille Calmette and Guerin, or BCG. In this embodiment the recombinant BCG
expresses major extracellular proteins of pathogenic mycobacteria including, but not limited to,
M. tuberculosis, M. leprae andM bovis, to name but a few.
The major extracellular proteins expressed by the recombinant BCG include, but are not
limited to, the 12 kDa, 14 kDa, 16 kDa, 23 kDa, 23.5 kDa, 30 kDa, 32A kDa, 32B kDa, 45 kDa,
58 kDa, 71 kDa, 80 kDa, and 110 kDa of Mycobacterium sp. and respective analogs, homologs
and subunits thereof including recombinant non-fusion proteins, fusion proteins and derivatives
thereof. It is apparent to those of ordinary skill in the art that the molecular weights used to
identify the major extracellular proteins of Mycobacteria and other intracellular pathogens are
only intended to be approximations. Those skilled in the art of recombinant technology and
molecular biology will realize that it is possible to co-express (co-translate) these proteins with
additional amino acids, polypeptides and proteins, as it its also possible to express these
proteins in truncated forms. The resulting modified proteins are still considered to be within
the scope of the present invention whether termed native, non-fusion proteins, fusion proteins,
hybrid proteins or chimeric proteins. For the purposes of the present invention, fusion proteins
are defined to include, but not limited to, the products of two or more coding sequences from
different genes that have been cloned together and that, after translation, form a single
polypeptide sequence.
The present invention also describes recombinant attenuated intracellular pathogen
vaccinating agents that over express non-fusion proteins from at least one other intracellular
pathogen. This is accomplished by using extrachromosomal nucleic acids to express at least
one recombinant immunogenic antigen gene and placing this gene(s) under the control of non-
heat shock gene promoters or non-stess protein gene promoters, preferably protein-specific
promoter sequences. Consequently, vaccines are provided having non-fusion, recombinant
immunogenic antigens expressed in greater quantities than possible when genes encoding for
recombinant immunogenic antigens are stably integrated into the vaccinating agent's genomic
DNA. As a result, intracellular pathogen vaccines having surprisingly superior specificity and
potency than existing subunit or attenuated intracellular pathogen vaccines are provided.
Moreover the present invention describes methods of treating and preventing
mammalian diseases caused by intracellular pathogens using the vaccines of the present
invention. A partial list of the many intracellular pathogens that may be used as the attenuated
vaccinating agents and/or the source of the recombinant immunogenic antigens includes, but is
not limited to, Mycobacterium bovis, M. ti/berculosis, M. leprae, M. kansasii, M. avium,
Mycobacterium sp., Legionella pneumophila, L. longbeachae, L. bozemanii, Legionella sp.,
Rickettsia rickettsii, Rickettsia typhi, Rickettsia sp., Ehrlichia chaffeensis, Ehrlichia
phagocytophila geno group, Ehrlichia sp., Coxiella burnetii, Leishmania sp, Toxpolasma
gondii, Tiypanosoma cruzi, Chlamydia pneumoniae, Chlamydia sp, Listeria monocytogenes,
Listeria sp, and Histoplasma sp. In one embodiment of the present invention a recombinant
BCG expressing the 30 kDa major extracellular protein of M. tuberculosis is administered to
mammals using intradermal inoculations. However, it is understood that the vaccines of the
present invention may be administered using any approach that will result in the appropriate
immune response including, but not limited to, subcutaneous, intramuscular, intranasal,
intraperitoneal, oral, or inhalation. Following a suitable post inoculation period, the mammals
were challenged with an infectious M. tuberculosis aerosol. Mammals receiving the vaccine of
the present invention were remarkably disease free as compared to mammals receiving BCG
alone, the major extracellular protein alone, or any combinations thereof.
Other objects and features and advantages of the present invention will be apparent to
those skilled in the art from a consideration of the following detailed description of preferred
exemplary embodiments thereof taken in conjunction with the Figures which will first be
described briefly.
accompanyinG
Brief Description of the/Drawings
FIG. 1 depicts Coomassie blue stained gels labeled 1 a and 1 b illustrating the secretion of
Mycobacterium tuberculosis recombinant 30 kDa by transformed strains of BCG from culture
filtrates.
FIG. 2 graphically depicts the results from two experiments labeled 2 a and 2 b designed
to compare skin tests results of guinea pigs inoculated with the recombinant BCG vaccine
expressing the 30 kDa major extracellularCprotein of M. tuberculosis, with BCG alone, with the
recombinant 30 kDa protein alone, or with a sham vaccine.
G
FIG. 3 graphically depicts the weight change in guinea pigs labeled 3 a and 3 b following
post immunization challenge with tuberculosis.
FIG. 4a graphically depicts Colony Forming Units (CFU) of infectious M. tuberculosis
recovered from guinea pigs' lungs following post immunization challenge withM tuberculosis.
FIG. 4b graphically depicts Colony Forming Units (CFU) of infectious M. tuberculosis
recovered from guinea pigs' spleens following post immunization challenge withM tuberculosis.
FIG. 5 graphically depicts the skin test response of guinea pigs to sham vaccine, BCG
alone and BCG administered with recombinant 30 kDa ofM tuberculosis.
Detailed Description of the Invention
The present invention is directed generally to vaccines and immunotherapeutics for
treating and preventing infections in humans and animals caused by intracellular pathogens.
Specifically, the present invention is directed at optimizing intracellular pathogen antigen
presentation to enable the immunotherapeutic and/or vaccine recipient to generate the
maximum immune response to important therapeutic and prophylactic proteins. The present
inventors, through years of research and experimentation, have surprisingly discovered that
successful therapy and prophylaxis of intracellular pathogen infections using extracellular
proteins derived from the intracellular pathogen is a function of protein presentation to the
host.
Antigen presentation encompasses a group of variables that determine how a recipient
processes and responds to an antigen. These variables can include, but are not limited to,
adjuvants, vaccine component concentration, carrier molecules, haptens, dose frequency and
route of administration. The present inventors have demonstrated that identical antigens
compounded differently will result in statistically significant response variations in genetically
similar, hosts. For example, two vaccine preparations of the 30 kDa extracellular protein ofM.
tuberculosis were compounded using the same protein and adjuvant concentrations. One group
of guinea pigs was administered a vaccine containing only the 30 kDa protein and adjuvant; a
second guinea pig group was administered the same vaccine as the first except that IL-12 was
added to the second vaccine. When the mean immune responses of both groups were
compared, the guinea pigs receiving the vaccine plus IL-12 demonstrated a statistically
significant superior immune response.
The present invention describes the union of two technologies, one known for over
eighty years, the other a product of the 1990's. Together, they represent an entirely new and
surprisingly effective approach to presenting intracellular pathogens' extracellular proteins to
recipients and inducing remarkably robust protective immune responses thereto. The present
inventors have attempted over 100 different antigen presentation methods using the
extracellular proteins of Mycobacterium tuberculosis as an exemplary intracellular pathogen.
However, in spite of the many successes realized by the present inventors, none had induced an
immune response superior to that seen using the BCG vaccine alone.
Briefly stated, and intended solely as a general example, the present invention includes
vaccines for intracellular pathogens using attenuated, or avirulent, recombinant intracellular
pathogens (the "vaccinating agent") that express and secrete recombinant immunogenic
antigens of the same, another species, or both (the "immunogen(s)"); the vaccinating agent and
immunogen(s) are referred to collectively as the "vaccines" of the present invention. The
vaccines are administered using one or more routes, including, but not limited to,
subcutaneous, intramuscular, intranasal, intraperitoneal, intradermal, oral, or inhalation. The
vaccinating agents of the present invention survive within the recipient expressing and
secreting the immunogen(s) in situ (status).
Without wishing to be bound to this theory, the present inventors have proposed that
the immunogenic antigens of opportunistic pathogens such as Legionella sp. can illicit
protective immune responses with greater ease than similar immunogenic antigens of more
traditional animal pathogens such as Mycobacterium sp. Selective pressures may have
afforded pathogens such as Mycobacterium sp., that co-evolved with their natural hosts,
immune evading mechanisms that incidental, or opportunistic, pathogens lack. Consequently,
significantly more powerful vaccinating agents and immunogens must be developed to elicit
protective immune responses against pathogenic Mycobacteria than those required to elicit
protective immunity against pathogens for which humans are not a primary host.
The present inventors have previously demonstrated the extracellular proteins from the
opportunistic intracellular pathogen Legionella sp. affords animals significant immune
protection when administered in purified form or in cocktails using either complete or
incomplete Freund's adjuvant. (See USPN 5,108,745, which is incorporated herein by
reference.) However, attempts to obtain similar protective immune responses using M.
tuberculosis extracellular proteins under similar conditions have not been as successful.
Consequently, the present inventors have proposed that over-expression of extracellular non-
fusion proteins may be an important aspect of antigen presentation and the development of
protective immune responses. However, it is understood that while the over-expression of non-
fusion immunogenic extracellular proteins may be one important factor in eliciting protective
immunity, it is not believed to be the only immunostimulatory factors the vaccines of the
present invention provide.
The present invention is ideally suited for preparing highly effective immunoprotective
vaccines against a variety of intracellular pathogens including, but not limited to BCG strains
over-expressing the major extracellular non-fusion proteins of M. tuberculosis, M. bovis or M.
leprae. Each vaccine of the present invention can express at least one immunogen of various
molecular weights specific for a given intracellular pathogen. For example, the present
inventers have previously identified M. tuberculosis immunogens that can include, but are not
limited to, the major extracellular proteins 12 kDa, 14 kDa, 16 kDa, 23 kDa, 23.5 kDa, 30 kDa,
32A kDa, 32B kDa, 45 kDa, 58 kDa, 71 kDa, 80 kDa, 110 kDa and respective analogs,
homologs and subunits thereof including recombinant non-fusion proteins, fusion proteins and
derivatives thereof. (See pending United States Patent Applications serial numbers
08/156,358, 09/157,689, 09/175,598, 09/226,539, and 09/322,116, the entire contents of which
are hereby incorporated by reference). It is apparent to those of ordinary skill in the art that the
molecular weights used to identify the major extracellular proteins of Mycobacteria and other
intracellular pathogens are only intended to be approximations. Those skilled in the art of
recombinant technology and molecular biology will realize that it is possible to co-express (co-
translate) these proteins with additional amino acids, polypeptides and proteins, as it its also
possible to express these proteins in truncated forms. The resulting modified proteins are still
considered to be within the scope of the present invention whether termed native, non-fusion
proteins, fusion proteins, hybrid proteins or chimeric proteins. For the purposes of the present
invention, fusion proteins are defined to include, but not limited to, the products of two or more
coding sequences from different genes that have been cloned together and that, after
translation, form a single polypeptide sequence.
Antigen expression, including extracellular proteins, is generally enhanced when genes
encoding for recombinant non-fusion proteins are located on, and under the control of, one or
more plasmids (extrachromosomal DNA) rather than integrated into the host genome.
Moreover, protein expression driven by promoter sequences specific for a particular protein
provide enhanced expression and improved protein folding and processing of non-fusion-
protein antigens. Therefore, the present invention provides recombinant extracellular non-
fusion proteins encoded on extrachromosomal DNA that are controlled by non-heat shock gene
promoters or non-stress protein gene promoters, preferably protein-specific promoter
sequences.
The present invention provides recombinant attenuated intracellular pathogen
vaccinating agents such as rBCG that express their own endogenous extracellular proteins in
addition to recombinant extracellular non-fusion proteins of closely related and/or other
intracellular pathogens. However, it has been demonstrated through 80 years of studies that
BCG's endogenous extracellular proteins alone do not provide complete protection in all
recipients. Furthermore, as will be explained in greater detail below, the present inventors
have also demonstrated that merely co-injecting M. tuberculosis extracellular proteins along
with traditional BCG does not result in vaccines superior to BCG alone.
In one embodiment of the present invention the vaccine includes a recombinant BCG
vaccinating agent expressing only one immunogen, for example the 30 kDa major extracellular
protein ofM tuberculosis. In another embodiment of the present invention the recombinant
BCG may express two or more immunogens, for example the 23.5 kDa and the 30 kDa major
extracellular proteins of M. tuberculosis. This latter embodiment may be particularly effective
as a vaccine for preventing diseases in mammals. The present inventors have proposed the
non-limiting theory that the simultaneous over expression of the 23.5 kDa and the 30 kDa
major extracellular proteins of M. tuberculosis by a recombinant BCG may act synergistically
to heighten the mammalian protective immune response against the intracellular pathogens of
the present invention. This theory is partially based on the observation that wild-type and
recombinant BCG are deletion mutants of M bovis that do not naturally express their own 23.5
kDa major extracellular protein.
For brevity sake, and due to the immensely complex description that would ensue, but
not intended as a limitation, the present invention will be more specifically described using a
recombinant BCG as the vaccination agent and M. tuberculosis extracellular non-fusion
proteins, specifically the 30 kDa major extracellular non-fusion protein, as an exemplary
embodiment of the present invention. It is understood that any recombinant immunogenic
antigen may be expressed by any recombinant attenuated intracellular pathogen, and that the
vaccines of the present invention are not limited to BCG as the vaccinating agent and the major
extracellular non-fusion proteins ofM tuberculosis as the immunogens.
In order to determine the effects of vaccinating agent strain variation, two different
BCG strains were used to prepare the various embodiments of the present invention: BCG Tice
and BCG Connaught, Wild-type M. bovisBCG Tice was purchased from Organon and wild-
type M. bovis BCG Connaught was obtained from Connaught Laboratories, Toronto, Canada.
The strains were maintained in 7H9 medium pH 6.7 (Difco) at 37°C in a 5% C02-95% air
atmosphere as unshaken cultures. Cultures were sonicated once or twice weekly for 5 min in a
sonicating water bath to reduce bacterial clumping.
Recombinant BCG TICE (YBCG30 Tice) expressing theM tuberculosis 30 kDa major
extracellular non-fusion protein was prepared as follows. The plasmid pMTB30, a
recombinant construct of the E. co/Z/mycobacteria shuttle plasmid pSMT3, was prepared as
previously described by the present inventors in Harth, G, B.-Y. Lee and M.A. Horwitz. 1997.
High-level heterologous expression and secretion in rapidly growing nonpathogeiiic
mycobacteria of four major Mycobacterium tuberculosis extracellular proteins considered to
be leading vaccine candidates and drug targets. Infect. Immun. 65:2321-2328, the entire
contents of which are hereby incorporated by reference.
Briefly, plasmid pMTB30 was engineered to express the M. tuberculosis Erdman 30
kDa major extracellular non-fusion protein from its own promoter (or any non-heat shock and
non-stress protein gene promoter) by inserting a large genomic DNA restriction fragment
containing the 30 kDa non-fusion protein gene plus extensive flanking DNA sequences into the
plasmid's multi-cloning site using methods known to those skilled in the art of recombinant
DNA technology. The plasmid was first introduced into K coli DH5a to obtain large
quantities of the recombinant plasmid. The recombinant E. coli strain, which was unable to
express the M. tuberculosis 30 kDa non-fusion protein, was grown in the presence of 250
ug/ml hygromycin and the plasmid insert's DNA sequence was determined in its entirety. The
plasmid was introduced into M. smegmatis by electroporation using 6.25 kV/cm, 25 uF, and
1000 mfl as the conditions yielding the largest number of positive transformants. The present
inventors verified the presence of the recombinant plasmid by growth in the presence of 50
ug/ml hygromycin and the constitutive expression and export of recombinant 30 kDa non-
fusion protein by polyacrylamide gel electrophoresis and immuoblotting with polyvalent,
highly specific rabbit anti-30 kDa non-fusion protein immunoglobulin using methods known to
those skilled in the art of recombinant DNA technology. Additionally, the inventors verified
the cprrect expression and processing of the recombinant M. tuberculosis 30 kDa non-fusion
protein, which was indistinguishable from its native counterpart by N-terminal amino acid
sequencing.
The recombinant pSMT3 plasmid pMTBSO was subsequently introduced intoM bovis
BCG Tice using 6.25 kV/cm, 25 F, and 200 as the optimal electroporation conditions.
Transformants were incubated in 7H9 medium supplemented with 2% glucose for 4 h at 37°C
in an environmental shaker and subsequently plated on 7H11 agar with 20 ug/ml hygromycin.
The concentration of hygromycin was gradually increased to 50 ug/ml as the transformants
were subcultured to a new growth medium. Recombinant BCG Tice cultures were maintained
under the same conditions as the wild-type except that the 7H9 medium contained 50 (ig/ml
hygromycin.
The expression and export of recombinant M. tuberculosis 30 kDa non-fusion protein
were verified by polyacrylamide gel electrophoresis and immunoblotting with polyvalent,
highly specific rabbit anti-30 kDa non-fusion protein immunoglobulin. Typically, 1 in 10
transformants expressed and exported significantly larger quantities of recombinant non-fusion
protein than the other transformants; 2 such transformants were chosen and a large stock of
these transformants was prepared and frozen at -70° C in 7H9 medium containing 10%
glycerol. These transformants were used for vaccine efficacy studies in guinea pigs. FIG la
shows the expression of the M. tuberculosis 30 kDa major extracellular non-fusion protein by
recombinant BCG Tice on SDS-PAGE gels and immunoblots. The recombinant strain
expressed much more of the M. tuberculosis 30 kDa major extracellular non-fusion protein
than the wild-type both on Coomassie blue stained gels and immunoblots.
Next a recombinant M. bovis BCG Connaught strain (rBCG30 Conn) expressing theM
tuberculosis 30 kDa major extracellular non-fusion protein was prepared similarly to that
described above for recombinant BCG Tice (rBCG30 Tice) using the aforementioned pMTB30
plasmid. It was maintained in medium containing hygromycin at a concentration of 50 ug/ml
under the same conditions as described for the recombinant BCG Tice strain. FIG. lb shows
the expression of the M. tuberculosis 30 kDa major extracellular non-fusion protein by
recombinant BCG Connaught on SDS-PAGE gels and immunoblots. The recombinant strain
expressed much more of the M. tuberculosis 30 kDa major extracellular non-fusion protein
than the wild-type both on Coomassie blue stained gels and immunoblots.
Plasmid stability of recombinant strains of BCG was assessed biochemically. This
biochemical analysis demonstrated that in the presence of hygromycin, broth cultures of the
recombinant BCG strains maintain a steady level of recombinant non-fusion protein expression
over a 3 month growth period. In the absence of hygromycin, the same cultures show only a
slight decrease of non-fusion protein expression (on a per cell basis), indicating that the
recombinant plasmid is stably maintained and only very gradually lost in bacteria growing
without selective pressure (FIG. la and FIG. lb, lane 3).
It is understood that using the methods described above in conjunction with methods
known to those skilled in the art of recombinant DNA technology, recombinant BCG strains
expressing theM tuberculosis 32(A) kDa major extracellular non-fusion protein, 16 kDa major
extracellular non-fusion protein, 23.5 kDa major extracellular non-fusion protein, and other M.
tuberculosis major extracellular non-fusion proteins can be prepared. Furthermore, similar
methodologies can be used to prepare recombinant BCG strains expressing M. leprae major
extracellular non-fusion proteins including, but not limited to the M. leprae 30 kDa major
extracellular non-fusion protein homolog of the M. tuberculosis 30 kDa major extracellular
non-fusion protein (a.k.a. Antigen 85B), the M. leprae 32(A) kDa major extracellular non-
fusion protein homolog of the M. tuberculosis 32(A) kDa major extracellular non-fusion
protein (a.k.a. Antigen 85A), and other M. leprae major extracellular non-fusion proteins.
Additionally, similar methodologies also can be used to prepare recombinant M. bovis BCG
expressing the M. bovis 30 kDa major extracellular non-fusion protein homolog of the M
tuberculosis 30 kDa major extracellular non-fusion protein (a.lca. Antigen 85B), the M. bovis
32(A) kDa major extracellular non-fusion protein homolog of theM tuberculosis 32(A) kDa
major extracellular protein (a.k.a. Antigen 85A), and other M. bovis major extracellular
proteins.
Following the successful vaccine production the vaccines of the present invention are
tested for safety and efficacy using an animal model. The studies utilized guinea pigs because
the guinea pig model is especially relevant to human tuberculosis clinically, immunologically,
and pathologically. In contrast to the mouse and rat, but like the human, the guinea pig a) is
susceptible to low doses of aerosolized M. tuberculosis; b) exhibits strong cutaneous DTH to
tuberculin; and c) displays Langhans giant cells and caseation in pulmonary lesions. However,
whereas only about 10% of immunocompetent humans who are infected withM tuberculosis
develop active disease over their lifetime (half early after exposure and half after a period of
latency), infected guinea pigs always develop early active disease. While guinea pigs differ
from humans in this respect, the consistency with which they develop active disease after
infection withM tuberculosis is an advantage in trials of vaccine efficacy.
. The immunization inoculums made in accordance with the teachings of the present
invention were prepared from aliquots removed from logarithmically growing wild type or
recombinant BCG cultures (the "bacteria"). Each aliquot of bacteria was pelleted by
centrifugation at 3,500 x g for 15 min and then washed with 1 x phosphate buffered saline (1 x
PBS, 50 mM sodium phosphate pH 7, 150 mM sodium chloride). The immunization
inoculums were then resuspended to a final concentration of 1 x 104 colony forming units per
ml in 1 x PBS and contained 1,000 viable bacteria per 100 ul.
Specific-pathogen free 250-300 g outbred male Hartley strain guinea pigs from Charles
River Breeding Laboratories, in groups of 9, were immunized intradermally with one of the
following: 1) BCG Connaught [103 Colony Forming Units (CFU)] one time only (time 0
weeks); 2) rBCG30 Connaught (103 CFU) one time only (time 0 weeks); 3) purified
recombinant M. tuberculosis 30 kDa major extracellular non-fusion protein (r30), 100 ug in
100 ul Syntex adjuvant formulation (SAF), three times three weeks apart (time 0, 3, and 6
weeks); SAF consisted of Pluronic L121, squalane, and Tween 80, and in the first
immunization, alanyl muramyl dipeptide; and 4) SAF only (100 p) (Sham-immunized), three
times three weeks apart (time 0, 3, and 6 weeks). An additional group of 3 animals was sham-
immunized with SAF only (100 ul) and used as a skin test control. These and three to six other
sham-immunized animals served as uninfected controls in the challenge experiments.
Nine weeks after the only immunization (BCG and rBCG30 groups) or first
immunization (r30 group and sham-immunized skin-test group), guinea pigs were shaved over
the back and injected intradermally with 10 ug of purified recombinant M. tuberculosis 30 kDa
major extracellular non-fusion protein (r30) in 100 pi phosphate buffered saline. After 24
hours, the diameter of erythema and induration was measured. (A separate group of sham-
immunized animals from the ones used in the challenge studies was used for skin-testing.
Sham-immunized animals used in challenge studies were not skin-tested to eliminate the
possibility that the skin-test itself might influence the outcome).
Nine weeks after the first or only immunization and immediately after skin-testing,
animals were challenged with an aerosol generated from a 10 ml single-cell suspension
containing 1 x 105 colony-forming units (CFU) of M. tuberculosis. Mycobacterium
tuberculosis Erdman strain (ATCC 35801) was passaged through outbred guinea pigs to
maintain virulence, cultured on 7H11 agar, subjected to gentle sonication to obtain a single cell
suspension, and frozen at -70°C for use in animal challenge experiments. The challenge
aerosol dose delivered ~40 live bacilli to the lungs of each animal. The airborne route of
infection was used because this is the natural route of infection for pulmonary tuberculosis. A
large dose was used so as to induce measurable clinical illness in 100% of control animals
within a relatively short time frame (10 weeks). Afterwards, guinea pigs were individually
housed in stainless steel cages contained within a laminar flow biohazard safety enclosure and
allowed free access to standard laboratory chow and water. The animals were observed for
illness and weighed weekly for 10 weeks and then euthanized. The right lung and spleen of
each animal were removed and cultured for CFU o£M. tuberculosis.
In each of the two experiments, the sham-immunized animals and animals immunized
with wild-type BCG exhibited little or no erythema and induration upon testing with
recombinant 30 kDaM tuberculosis major extracellular non-fusion protein (r30). In contrast,
animals immunized with r30 or rBCG30 exhibited marked erythema and induration that was
significantly higher than in the sham-immunized or wild-type BCG immunized animals (Table
1 and FIG. 2).
In each of the two experiments, uninfected controls gained weight normally after
challenge as did animals immunized with either rBCG30 or wild-type BCG (FIG. 3). Indeed
there were no significant differences in weight gain among these three groups. In contrast,
sham-immunized animals and to a lesser extent r30 immunized animals, exhibited diminished
weight gain over the course of the experiment (Table 2 and FIG. 3). Hence, after challenge
withM. tuberculosis, both BCG and rBCG30 protected animals completely from weight loss, a
major physical sign of tuberculosis in humans, and a hallmark of tuberculosis in the guinea pig
model of this chronic infectious disease.
In each of the two experiments, at the end of the 10 week observation period, guinea pigs
were euthanized and the right lung and spleen of each animal was removed aseptically and
assayed for CFU of M. tuberculosis. Sham-immunized animals had the highest bacterial load
in the lungs and spleen (Table 3 and FIG. 4a and FIG. 4b). Animals immunized with r30 had
fewer organisms in the lungs and spleen than the sham-immunized animals; BCG-immunized
animals had fewer organisms than r30-immunized animals; and remarkably, rBCG30-
immunized animals had fewer organisms than BCG-immunized animals. Statistical tests
employing two way factorial analysis of variance methods to compare means demonstrated that
the means of the four "treatment" groups (Sham, r30, BCG, and rBCG30) in Experiment 1
were not significantly different from the means of the four treatment groups in Experiment 2
and that it was therefore appropriate to combine the data in the two experiments. The
combined data is shown in Table 4 and FIG. 3. Of greatest interest and importance, the
rBCG30-immunized animals had 0.5 log fewer organisms in the Jungs and nearly 1 log fewer
organisms in the spleen than BCG-immunized animals. On statistical analysis, employing
analysis of variance methods to compare means and the Tukey-Fisher least significant
difference (LSD) criterion to assess statistical significance, the mean of each of the four groups
in both the lungs and spleens was significantly different from the mean of each of the others
(Table 4). Differences between the rBCGSO and BCG immunized animals in the lungs were
significant at p=0.02 and in the spleens at p=0.001. Paralleling the differences in CFU in the
lungs, on gross inspection, lungs of rBCG30-immunized animals had less lung destruction than
BCG-immunized animals (20 ± 4% versus 35 + 5% mean ± SE).
Thus, administration of recombinant BCG expressing theM tuberculosis 30 kDa major
extracellular non-fusion protein induced high level protection against aerosol challenge with M
tuberculosis in the highly susceptible guinea pig model of pulmonary tuberculosis. In contrast,
as described in the examples below, administration of the same mycobacterial extracellular
non-fusion protein (the M. tuberculosis recombinant 30 kDa major extracellular non-fusion
protein) in adjuvant in combination with BCG does not induce high level protection against
aerosol challenge withM tuberculosis; nor does administration of recombinant M. smegmatis
expressing the PI. tuberculosis 30 kDa major extracellular non-fusion protein; nor does
administration of the M. tuberculosis 30 kDa major extracellular non-fusion protein in
microspheres that are of the same approximate size as BCG and like BCG slowly release the
proteins over 60-90 days; nor does administration of the M. tuberculosis 30 kDa major
extracellular non-fusion protein encapsulated in liposomes.
A very surprising aspect of this invention is that the rBCG30 strain induced protection
superior to wild-type BCG even though the wild-type expresses and secretes an endogenous
highly homologous 30 kDa major extracellular protein. (See FIG. 1). The gene encoding the
30 kDa protein from substrain BCG Connaught has not been sequenced. However, the
sequence of the 30 kDa protein of two other substrains of BCG, deduced from the sequence of
the cloned gene of these substrains, differs from theM tuberculosis protein by only one amino
acid (BCG Paris 1173 P2) or by 5 amino acids including two additional amino acids (BCG
Tokyo). (See pages 3041-3042 of Flarth, G., B.-Y. Lee, J. Wang, D.L. Clemens, and M.A.
Horwitz. 1996. Novel insights into the genetics, biochemistry, and imrmmocytochemisliy of
the 30-lcilodalton major extracellular protein of Mycobacterium tuberculosis. Infect. Immun.
64:3038-3047 the entire contents of which are herein incorporated by reference). Hence, the
improved protection of the recombinant strain is unlikely to be due to the small amino acid
difference between the recombinant and endogenous proteins. More likely, it is due to the
The following Examples serve to illustrate the novel aspect of the present invention.
Each example illustrates a means of delivering the immunogens of the present invention using
techniques closely related to, but different from the vaccine of the present invention.
Specifically, Example 1 demonstrates that when the immunogens of the present invention are
administered with, but not expressed in vivo by BCG, a high level of protective immunity is
not achieved.
Example 2 demonstrates that the in vivo expression of the immunogens of the present
invention using a Mycobacterium sp. closely related to BCG, but unable to replicate in
mammalian hosts, fails to induce significant levels of protection against challenge with M.
tuberculosis. Examples 3 and 4 demonstrate that the slow release of the immunogens of the
present invention by synthetic vaccine microcarriers also fails to induce significant levels of
protection against challenge withM tuberculosis.
Therefore, the following Examples serve to highlight the completely surprising and
remarkable advance that the intracellular pathogen vaccines of the present invention represents
to the field of infectious disease immunology.
Examples
Example 1
Immunization of guinea pigs with BCG plus recombinant M. tuberculosis 30 kDa major
extracellular protein (V30) does not induce high level protection against challenge with M.
tuberculosis.
We previously immunized guinea pigs with BCG plus r30 in a powerful adjuvant (SAF,
Syntex Adjuvant Formulation). The r30 protein (100 u.g per immunization) was administered
intradermally three times. This induced a strong cutaneous delayed-type hypersensitivity (C-
DTH) response to r30 (FIG. 5). Indeed, the C-DTH response was comparable to that induced
by recombinant BCG expressing r30. Nevertheless, immunization with both BCG and r30 did
not induce high level protection against challenge with M. tuberculosis (Table 5). Animals
immunized with both BCG and r30 did not have lower levels of CFU in the lungs and spleen
than animals immunized with BCG alone. This result is in direct contrast to the result
described above in which animals immunized with recombinant BCG expressing r30 exhibited
high level protection when challenged withM tuberculosis.
Example 2
Immunization of guinea pigs with live recombinant M. smegniatis expressing the M.
tuberculosis 30 kDa major extracellular protein fr30) in a form indistinguishable from the
native form does not induce high level protection against challenge withM tuberculosis.
In one of the same experiments in which we immunized animals with BCG, we
immunized guinea pigs with live recombinant M smegmatis expressing theM tuberculosis 30
kDa major extracellular protein (r30) in a form indistinguishable from the native form. The
expression and secretion of theM tuberculosis 30 kDa major extracellular protein (r30) by M.
smegmatis was equal to or greater than that of the recombinant BCG strain expressing and
secreting the M. tuberculosis 30 kDa major extracellular protein. Moreover, the dose of
recombinant M smegmatis, 10 bacteria, was very high, one million times the dose of
recombinant BCG (I03 bacteria), to more than compensate for the poor multiplication of M.
smegmatis in the animal host. To compensate even further, the recombinant M. smegmatis was
administered three times intradermally, whereas the recombinant BCG was administered only
once intradermally. Immunization with recombinant M. smegmatis expressing the r30 protein
induced a strong cutaneous delayed-type hypersensitivity (C-DTH) response to r30. Indeed,
the C-DTH response was comparable to or greater than that induced by recombinant BCG
expressing r30. Nevertheless, the live recombinant M. smegmatis expressing the M.
tuberculosis 30 kDa major extracellular protein did not induce high level protection against
challenge with M. tuberculosis (Table 6). Animals immunized with the live recombinant M.
smegmatis expressing the M. tuberculosis 30 kDa major extracellular protein did not have
lower levels of CFU in the lungs and spleen than animals immunized with BCG alone. This
result is in direct contrast to the result described above in which animals immunized with
recombinant BCG expressing r30 exhibited high level protection when challenged with M.
tuberculosis.
Example 3
Immunization of guinea pigs with microspheres that are of the same approximate size
as BCG and like BCG slowly release theM tuberculosis 30 kDa major extracellular protein
MO) over 60 - 90 days does not induce high level protection against challenge with M.
tuberculosis.
In one of the same experiments in which we immunized animals with rBCG30 and
BCG, we immunized guinea pigs with microspheres that are of the same approximate size as
BCG and like BCG slowly release theM tuberculosis 30 kDa major extracellular protein (r30)
over 60 - 90 days. One set of animals was immunized once with microspheres containing 10
mg of r30. Another set of animals was immunized three times with microspheres containing
3.3 mg of r30. This amount was calculated to greatly exceed the amount of r30 protein
expressed by the recombinant BCG strain. Immunization with either regimen of microspheres
induced a strong cutaneous delayed-type hypersensitivity (C-DTH) response to r30. Indeed,
the C-DTH response was comparable to that induced by recombinant BCG expressing r30.
Nevertheless, immunization with the microspheres that are of the same approximate size as
BCG and like BCG slowly release the M. tuberculosis 30 kDa major extracellular protein did
not induce high level protection against challenge with M. tuberculosis (Table 7). Animals
immunized with the microspheres did not have lower levels of CFU in the lungs and spleen
than animals immunized with BCG alone. This result is in direct contrast to the result
described above in which animals immunized with recombinant BCG expressing r30 exhibited
high level protection when challenged withM tuberculosis.
Example 4
- Immunization of guinea pigs with liposomes containing the M. tuberculosis 30 kDa
major extracellular protein does not induce high level protection against challenge with M.
tuberculosis.
In the same experiment as in Example 3, we immunized guinea pigs with liposomes
containing the M. tuberculosis 30 kDa major extracellular protein. The animals were
immunized three times with liposomes containing 50 u.g of r30. This induced a moderately
strong cutaneous delayed-type hypersensitivity (C-DTH) response to r30. The C-DTH
response was greater than that induced by BCG and control liposomes but less than that
induced by recombinant BCG expressing r30. Nevertheless, immunization with liposomes
containing the M. tuberculosis 30 kDa major extracellular protein did not induce high level
protection against challenge with M. tuberculosis (Table 7). Animals immunized with the
liposomes containing theM tuberculosis 30 kDa major extracellular protein did not have lower
levels of CFU in the lungs and spleen than animals immunized with BCG alone. This result is
in direct contrast to the result described above in which animals immunized with recombinant
BCG expressing r30 exhibited high level protection when challenged withM tuberculosis.
The vaccines of the present invention represent an entirely new approach to the
therapeutic and prophylactic treatment of intracellular pathogens. Through a series of well
designed experiments and thoughtful analysis, the present inventors have thoroughly
demonstrated that protective immunity is only achieved when a precisely selected intracellular
pathogen, or closely related species, is transformed to express recombinant extracellular
proteins of the same or different intracellular pathogen in accordance with the teachings of the
present invention.
The present invention can also be used to provide prophylactic and therapeutic benefits
against multiple intracellular pathogens simultaneously. For example a recombinant attenuated
intracellular vaccinating agent like M. bovis can be designed to expressed immuno-protective
immunogens against M. tuberculosis and Legionella sp. simultaneously. Consequently, great
efficiencies in delivering vaccines could be accomplished. The non-limiting examples of
recombinant BCG expressing the major extracellular proteins ofM tuberculosis not only serve
as a fully enabling embodiment of the present invention, but represent a significant advance to
medicine, and humanity as a whole.
Therefore, it is apparent that while a preferred embodiment of the invention has been
shown and described, various modifications and changes may be made without departing from
the true spirit and scope of the invention.
WE CLAIM:
1. An immunogenic composition comprising:
A recombinant Bacille Calmette-Guerm (BCG) bacterium having an
extrachromosomal nucleic acid sequence comprising a gene encoding for
the Mycobacteria tuberculosis 30 kDa major extracellular protein,
wherein said Mycobacteria tuberculosis 30 kDa major extracellular
protein is expressed and wherein said extrachromosomal nucleic acid
sequence is under the control of non-heat shock gene promoters or non-
stress protein gene promoters.
2. The immunogenic composition as claimed in claim 1 wherein said major
extracellular protein is a non-fusion protein.
3. An immunogenic composition as claimed in claim 1 or 2 capable of being used as
a medicament, wherein the medicament is a vaccine.
4. An immunogenic composition as claimed in claim 1 to 2 for the manufacture of a
medicament for induction of an immune response in an animal.
Vaccines and immunotherapeulics for preventing intracellular pathogen diseases in mammals are provided that con-
sist of recombinant attenuated intracellular pathogens that have been transformed to express recombinant immunogenic antigens of
the same r other intracellular pathogens. Exemplary vaccines and immunotherapeulics include attenuated recombinant Mycobacte-
ria expressing the major extracellular non-fusion proteins of Mycobacterial and/or other intracellular pathogens. These exemplary
vaccines are shown to produce surprisingly potent protective immune response in mammals that surpass those of any previously
known anti-mycobaclerium vaccine. More specifically, a recombinant BCG expressing the 30 kDa major extracellular non-fusion
protein of Mycobacterium tubercolosis is provided. Additionally, methods for preventing and treating diseases caused by intracellu-
lar pathogens are provided. The methods of treating and preventing intracellular pathogen diseases utilize the described surprisingly
efficacious vaccines and immunolherapeutics.

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Patent Number 234019
Indian Patent Application Number IN/PCT/2002/1299/KOL
PG Journal Number 18/2009
Publication Date 01-May-2009
Grant Date 29-Apr-2009
Date of Filing 18-Oct-2002
Name of Patentee THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
Applicant Address 1111, FRANKLIN STREET, 5TH FLOOR, OAKLAND, CA
Inventors:
# Inventor's Name Inventor's Address
1 HORWITZ MARCUS A 1275 STRADELLA ROAD, LOS ANGELES, CA 90077
2 HARTH GUNTER 1525 SAWTELLE BOULEVARD, #16, LOS ANGELES, CA 90025
PCT International Classification Number A61K 39/02
PCT International Application Number PCT/US2001/12380
PCT International Filing date 2001-04-16
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 09/550,468 2000-04-17 U.S.A.