|Title of Invention||
"AN AGGREGATED ANTIGENIC STRUCTURE"
|Abstract||The invention relates to a method for obtaining aggregated antigenic structures that are capable of enhancing an immune response to aggregate antigens administered systemically and/or mucosally generating powerful immune response and to the chemical structures resulting from the application of said method, to the formulations obtained from such structures and their use. The method describes the obtention of novel aggregate antigenic structures by using aggregating, delipidating or oxidating agents or compounds enabling the release of lipids from the particles and their heterogeneous aggregation, wherein aggregates with particle sizes of between 30 and 500 nm are subsequently selected by means of a molecular exclusion process. The aggregation state can also be provoket inside the yeast by changing incubation conditions. The resulting structures can be used conveniently adjuvated or in a formulation in which several antigens can be introduced, wherein synergism between said components is found with respect to the immunogenicity of the response obtained. The preparation may also contain stabilizers and preservatives. The resulting antigenic structures can be used in the pharmaceutical industry as preventive or therapeutic vaccine formulation both for human and veterinary use and as part of diagnostic system.|
|Full Text||Field of the Invention
The present invention relates to an aggregated antigenic structure having increased immunogenicity with the resulting formulation and a differential recognition by the immune system. Technical branch
The present invention is related to the medical branch, particularly with the use of new vaccine formulations.
The technical objective of the proposed invention is the development of a method for the preparation of aggregated antigenic structures and their formulations, able to potentiate the immunogenicity of the present antigens administered by systemic or mucosal routes.
The method described in the present invention generates antigenic aggregated structures of particulated antigens, the addition of other antigens, components with aggregating, delipidating or oxidizing characteristics, the post selection of aggregated particles between 30-500 nm size, and the formulation of those aggregates conveniently adjuvanted, favor the immunogenicity of the resulting antigenic composition. Previous Technique
Since the HBsAg is an efficient immunogen, it was the first vaccine candidate of a wide use in humans and the first licensed anti hepatitis B recombinant vaccine for universal use. HbsAg proteins are self assembling in 22 nm particles (Heerman KH, Gerlich WH, 1991 Surface protein of Hepatitis B virus. A Mclachlan, ed. CRC Press, Boca Raton, Ann Harbor, Boston, London, p.109). The molecular, cellular and genetic basis of the immune response to HBsAg has been extensively studied in a murine model (Milich, DR. 1987. Genetic and molecular basis for T- and B-cell recognition of hepatitis B viral antigens, Immunol Rev. 99:71). Formerly it had been studied how the variations of the physical chemical properties of the surface antigen affect its immunogenicity for MHC class I restricted CTL response was generated with only one low dose injection of the 22 nm particulated native antigen or with detergent denatured monomers without adjuvant (Schirmbeck, R. et al. 1994. Eur J Immunol. 24: 1088). It has also been investigated the immunogenicity
of a preparation of aggregates of the HBV surface antigen obtained by heat denaturation to produce particles of approximately 1 urn diameter. The type of in vivo antigenic processing has a fundamental influence on the efficiency of the primary T cell response as well as on the subclass spectrum of the involved T cell. In the presentation of peptides to the MHC apparently operates alternative processes for MHC class II CD4+ restricted T cells and for MHC class I CD8+ restricted T cells (Germain, RN. et al. 1993. Annu Rev Immunol. 11: 403). It has been described a new endosomal pathway for the exogenous HBsAg particle processing to present MHC class I restricted epitopes. This heat denatured 1|am diameter exogenous HBsAg particle processing occurs in macrophages but not in other cell types and is accompanied with regurgitation of antigenic peptides from the processing macrophage. This exogenous antigen MHC class I restricted peptide generating process has been tentatively designed as the phagocytic pathway. The native 22 nm HBsAg particles are processed mainly by the endocytic and the 1 jam aggregates by the phagocytic pathways. In addition to the different in vitro processing of these two HBsAg exogenous preparations, their in vivo immunogenicity for class I CTL was markedly different when they were sent without adjuvants. The native HBsAg particle was highly immunogenic while the denaturalized surface antigen aggregates were of low immunogenicity (Schirmbeck, R. et al. 1995. J Immunol 155: 4676-4684). Other studies performed using fluorescence polarization suggest that the HBsAg particle is organized as a lipid bilayer which interacts with protein aggregates (Sonveaux N. 1995 Res Virol 146 (1):43-51). The HBsAg treatment with chloroform-methanol (2:1, v/v) 50% 1P1',3,3'-tetrametilurea did not affect the morphologic integrity of the particles (they maintained their mean diameter), although a major portion of its lipids was released. The antigenicity and the HBsAg polypeptide composition was not altered by the delipidation (Neurath AR et al 1978 Intervirology 10(5): 265-75).
Taking into account that particle aggregations are not produced in the stressing conditions of the production process, such as the presence ofchaotropic agents, moderate temperatures and highly concentrated solutions, the source of recombinant hepatitis B surface antigen particles aggregation has been studied using a combination of immunoaffinity and molecular size exclusion chromatography techniques. The investigation of factors conducing to an increase in the base of the peak corresponding to HBsAg in molecular exclusion chromatography demonstrated the existence of particle aggregates, in addition to the size variability of the HBsAg particle (Tleugabulova D. 1998 J Chromatogr B Biomed Sci Appl 707(1 -2):267-73, Tleugabulova D. 1997 Chromatographia 45: 317-320). As a result the aggregated antigen was obtained in the fraction corresponding to the large particle aggregates was obtained and not in the fraction were the native HBsAg protein was found, another result of this article corroborates that the aggregates are formed by 22 nm particles migrating as monomers and dimers in SDS-PAGE as well as the correctly folded surface antigen (Tleugabulova D, et a/. 1998 J Chromatogr B Biomed Sci Appl 25;716(1-2): 209-19).
Statement of the Invention:
Accordingly, the present invention relates to an aggregated antigenic structure having increased immunogenicity with the resulting formulation and a differential recognition by the immune system comprising;
a. One or more antigens of interest such as herein described and
b. Pharmaceutically acceptable adjuvants and aggregating agents.
Disclosure of the invention
One of the objectives of the present invention is a method to obtain aggregated antigenic structures of a higher immunogenicity than the antigens originating them. Said method includes the following steps:
A) Selection of the antigens of interest;
B) Addition of one or several antigens of the mixture in a medium favoring the
aggregation process, said medium may consist in chemical agents, oxidizing
agents or other components with aggregating capacity.
C) Incubation of the mixture.
D) Selection of the particle aggregate with, a size between 30 and 500 nm by
a process allowing the retention of these molecular sizes, such as molecular
exclusion chromatography, diafiltration and dialysis.
E) Preparation of the formulations by mixing the selected antigenic structures
in step (C) through the addition of the adjuvant of election and also the
potential addition of other antige
The aggregates separation is achieved by molecular size exclusion methods, among them molecular exclusion chromatography, dialysis, diafiltration or other method permitting the retention of molecular sizes between 30 and 500 nm.
We have also shown that although it is possible to generate aggregates of around 1 micrometer of size by non denaturing methods (maximum temperature 28°C), similar to those obtained by Schirmbeck (Schirmbeck, R. et a/. 1995. J Immunol 155: 4676-4684), these continue to be less immunogenic when evaluating the humoral response and DTH. Only those particle aggregates of a size between 30 and 500 nm, adjuvanted with alum, have demonstrated the generation of IgG levels significantly higher than the native antigen control, showing additionally a significant increase of the DTH and lgG2a responses. All this evidences the importance of the later selection of the antigen by molecular exclusion chromatography. The cause of this performance may be given by the different presentation and or processing of the antigen or antigens of interest.
Moreover the present invention method foresees the adsorption of the resulting structures to such adjuvants as alum or calcium salts, oily or other commercially used adjuvant. It may be also added to the final formulation other antigens and stabilizing and preserving substances. Another object of the present invention is the aggregated antigenic structure obtained according to the previously described method, which favors an increase in the immunogenicity of the resulting formulation and a differential recognition by the immune system of the involved epitopes. Said aggregated antigenic structures are characterized by the presence of the hepatitis B virus surface antigen, alone or in combination with other antigens forming the aggregate. These other antigens are lipoproteins or hydrophobic, among them HBcAg, possessing additionally the intrinsic property of favoring the aggregation state between them by hydrophobic linkages. Other hydrophobic viral capsid and lipoprotein antigens have shown this capacity, among them the nucleocapsid antigen of the hepatitis C virus, the human papilloma virus
and HIV 1 and 2, besides the outer membrane of N. meningitidis in proteolyposome vesicles and some viral envelope antigens. Among the antigenic structures object of the present invention the associations of HBsAg with hydrophobic adjuvants are included which may be part of the aggregate by the same previously described method. In general the antigenic structures object of the present invention may be obtained by aggregation of at least one, two or more hydrophobic particles according to the described method and at least one of particulate character, and should be visible by electron microscopy as described in the examples. The aggregation of these structures favors the immune modulation, differential recognition and immunogenicity enhancement in a general fashion. Taking into account these characteristics of the antigenic structures object of the present invention, it is possible the use them for the rational design of preventive and therapeutic human and veterinary vaccines, through the systemic or mucosal routes and their use in diagnostic systems.
Among the advantages of the new preparations resulting from the use of the method for obtaining this type of antigens the following are found: increase of immunogenicity, co-trapping capacity for new adjuvants, immunomodulators and antigens during the aggregation.
The preparations resulting from the present invention method, depending on the inoculation route and species to be immunized may be used in volumes of 0.01 up to 10 ml_ and the antigen doses may vary between 0.001 and 1 mg in the final vaccine formulation.
Example 1. Preparation of vaccine formulations of aggregated of
surface antigen of the hepatitis B virus obtained by the cyclodextrins
The particles were obtained from the 22 nm native antigen by the controlled treatment of the antigen with chemical compounds with lipid subtracting activity from the particle, in this case cyclodextrins were used in concentrations higher than 1 mg/mL Depending on its concentration the
incubation time varied from 24 hours to 7 days. The incubation temperature used in this assay was of 28 degrees centigrade although it has been observed that at higher and lower temperatures it is also possible to obtain aggregates. The temperature is a factor favoring the partial delipidation process though oxidation and lipids subtraction. Later the different aggregates were analyzed by gel filtration and electron microscopy, finding sizes which varied from tenths nanometers up to particles that precipitated due to their huge size. After centrifugation to eliminate precipitated residues, the antigen was selected depending on its size for immunochemical analyses, which demonstrated a decreased level of lipids regarding the proteins level. It has been shown by HPLC that these aggregates have a high stability during the storage time. The controlled treatment of the antigen with P-cyclodextrins, between 5-100 mg/mL during 1 - 240 hours, at temperatures ranging from 20 to 37 °C, allow to obtain a size range that made possible the later election of the elution time for immunochemical analysis.
Afterwards the aggregated antigen was adsorbed to alum at a final concentration between 0.002 and 0.1 mg/mL and was used for immunogenicity assays.
One incubation variant with cyclodextrins at different times and temperatures involved the addition of immunomodulating compounds such as lypo-polysaccharides and saponins, that are part of the final aggregate adsorbed to alum to produce the final vaccine formulation.
Example 2. Preparation of vaccine formulations of surface antigen of hepatitis B virus aggregates using oxidizing agents. With the addition of oxidizing chemical substances to the normal antigen it was possible the delipidation in controlled time, temperature and concentration conditions in the same way that with cyclodextrins. Salts as ammonium peroxi-disulfate between 9 and 44 mM, permitted the generation of the delipidated antigen starting from the 22 nm antigen particles, to produce size increase by particle fusion. The optimal sizes were selected by gel filtration. La adjuvant adsorption was achieved on alum.
In the same way that in the example 1, it was possible to include in the aggregate different quantities of other adjuvants and immunomodulators during the incubation.
Example 3. Preparation of vaccine formulations of over-particulate chemical structures, obtained by modification of the incubation conditions of the yeast.
The particles were obtained naturally from the Picchia pastoris yeast strain, the antigen was selected during the purification process by its physical chemical characteristics. The antigen production process is submitted to long lasting culture time, higher than 100 hours and oxidative stressing conditions. This process makes possible that a part of the antigen remains in its 22 nm particle size native state but an important moiety gets aggregated and delipidated by the increase of the intracellular oxidative conditions, as demonstrated by the lipid and protein analyses done to samples of the different peaks from gel filtration. Finally the fraction is separated by HPLC gel filtration in TSK G5000 columns. This material reaches up to 10% of total the antigen which is actually discarded. Alum adjuvant adsorption is achieved in similar conditions as for the normal antigen.
The analysis of both antigens demonstrated that HBsAg gets aggregated in a process that involves a significant loss of lipids of all types which is shown for phospholipids of both antigens in the following table:
Composition ofHBsAg phospholipids (PL) separated by silica-gel.
With this example it is evidenced that a new over-particulated antigen may be obtained after a natural oxidizing and delipidating process. The stability of these aggregates would be based on the aggregation processes that may
occur during the elimination of lipids from the particles that could expose
hydrophobic regions and by protein polymerizations between particles when
sulphydril groups are exposed.
Example 4. Evaluation of the aggregated HBsAg inmunogenicity.
With the objective of evaluating the immunogenicity of the aggregated HBsAg
resulting from the example 3, adsorbed in alum or in PBS for mucosal route,
an immunization schedule was carried out with inoculations the days 0, 14
and 28 and retro-orbital blood extractions the day 42 and female Balb/c mice
of 10 to 15 weeks old were immunaized by intranasal and intramuscular
routes. The doses per mouse are presented in the table at the end of this
example, and the results are shown in figure 1A, and the HbsAg aggregate
are shown in figure 1B.
The statistical analysis of results was performed by the Student test and
p From this experiment it was demonstrated that it is possible to generate a
higher anti HBsAg IgG response when immunizing by mucosal or systemic
routes, regarding the normal antigen, in equal conditions. In the same figure it
is represented the comparison of this effect for the DTH response (bars),
which also resulted significantly higher for the aggregated variant.
The immunization groups are shown in the following table:
A- 5 |ig HBsAg delipidated (50-500 nm)/ PBS 1X IN
B- 10ng HBsAg delipidated (50-500 nm)/ PBS 1X IN
C- 5 ng HBsAg normal (22 nm)/ PBS 1X IN
D- 5 ng HBsAg delipidated (50-500 nm)/ Alum 0.5 mg/mL IM
E- 5 |ig HBsAg normal (22 nm)/ Alum 0.5 mg/mL IM
Example 5. Kinetics of the anti-HBsAg IgG response.
With the objective of studying the kinetics of the anti-HBsAg IgG response 10 groups of female 10-15 weeks old Balb/c mice were immunized. The schedule used was: inoculation the weeks 0, 2 and 18 and extractions pre immune at 4, 6, 8, 10, 12, 14, 16 y 20 weeks. The groups tested are described in the following table:
1 - 5 ^g HBsAg normal (22 nm)/ Alum IM
2-5 ^g HBsAg normal (22 nm)/PBS 1X IM
3- 5 jig HBsAg delipidated (example 3)/ Alum 0.5 mg/mL IM
4- 5 \ig HBsAg delipidated (example 3) / PBS 1X IM
5- 5 p.g HBsAg delipidated (example 1) / Alum 0.5 mg/mL IM
6- 5 \iQ HBsAg delipidated (example 1) / PBS 1X IM
7- 5 ng HBsAg delipidated (example 1) / Alum 0.5 mg/mL IM
8- 5 p.g HBsAg delipidated (example 1)/ PBS 1X IM
9- 5 ng HBsAg delipidated (example 1)/ Alum 0.5 mg/mL IM
10- 5 ng HBsAg delipidated (example 1)/ PBS 1X IM
The antigens of the groups 5 and 6, 7 and 8, and 9 and 10 were obtained by incubating at different times and concentrations of cyclodextrins obtaining different degrees of aggregation.
For the DTH experiment, the measurements were performed the days: 1 (1, 3), 2(1', 3'), 3(1", 3") and 5(1'", 3'")
The statistical analysis of results was performed by the Student test: p In this experiment it was corroborated that the delipidated HBsAg, with different degrees of aggregation, have immunological characteristics that distinguished each one. The larger immunogenicity and DTH response did not corresponded to the larger antigen size but to intermediate antigen sizes although according to the performance of the antibody appearance kinetics at the end of the experiment the larger immunogenicity corresponded to the variant with a higher degree of aggregation. However it was observed a significant increase of the DTH response in the groups immunized with alum adjuvant as compared to those immunized-with the antigen in PBS, the group of aggregated antigen with an intermediate size generated the larger increases with arrived to be significant the day 56. In figure 2a the individual titers the day 56 are represented for all immunized groups. In this figure are also represented the results of the DTH experiment performed during 5 days of the week 22, using 20 jj.g of HBsAg in the right leg and PBS in the left leg in an inoculation volume of 20 p,L All resting groups also had a significantly lower response regarding the difference in diameter between the right and left legs as compared to group 3, which was inoculated with alum adjuvanted HBsAg with an intermediate aggregation level, obtained as described in
example 3. It is worth to take into account that in the later examples it is demonstrated that the recognition in the case of over-particulated structures is wider regarding the epitopes recognized in the HBsAg, which indicates a better performance for this type of structure. Although from group 5 to group 10, the anti native HBsAg reactivity is similar to that obtained immunizing with native HBsAg during a major part of the time, a strong response is also obtained against other epitopes present in the aggregated antigen, see example 8, figure 4.
Example 6. Evaluation of the lgG1/lgG2a ratio.
With the objective of studying if a variation in the lgG1/lgG2a ratio existed due to the its linkage between the TH1/TH2 response, the sera of the D and E groups of the immunization schedule of example 4, were tested for anti IgG 1 and lgG2a antibody levels. This analysis was performed for the sera of the day 42 extraction. The lgG2a antibody levels increased significantly in the group immunized with the over-particulated antigen (50-500 nm) up to attaining an lgG1/lgG2a ratio closer to 1 as compared to the normal HBsAg also adjuvanted in alum (Figure 4).
The lgG1/2a ratio for the normal HBsAg group immunized with alum was 6.2 times higher to that found for the delipidated HBsAg group of intermediate size. From this experiment it could be concluded that the different presentation of the surface antigen not only generates a quantitative but also a qualitative change regarding the IgG type which is potentiated and the correlation of these variations in the IgG subclass pattern with an enhancement of the cellular response, corroborating the DTH assessment findings.
Example 7. Study of the anti- native HBsAg reactivity of the sera of mice immunized with different antigenic variants.
After the immunization of mice with the delipidated antigens obtained according to examples 1, 2 and 3, the reactivity of their sera was compared to that of the sera from the mice immunized with the normal antigen. As a result of this experiment it was observed that the immune response generated in the sera from the mice immunized with the different variants had
a different reactivity against the normal HBsAg (22 nm), the major reactivity was exhibited by the sera from mice immunized with the normal antigen, while for the different degrees of delipidation the reactivity against HBsAg was also different. Even existing high titers against their own immunogens the sera from mice immunized with immunized with highly oxidized variants did not recognized HBsAg, evidencing a different recognition of the generated antibodies with the different immunogens and demonstrating the different antigenic nature of the newly generated structures. Therefore the results of example 5 must be analyzed taking into account that although for the last three aggregated antigen variants similar anti native HBsAg responses are obtained, a response is also present against other HBsAg protein epitopes not recognized by immunizing with native HBsAg. Example 8. Recognition of lineal epitopes by the sera from mice immunized with different antigen variants.
With the objective of comparing the recognition of the antibodies generated by an over-particulated HBsAg obtained by the oxidation variant described in example 2, a mapping was performed on cellulose membrane containing linear HBsAg sequences (S region), 37 peptides of 12 aminoacids were synthesized each one overlapped in 6 until completing the whole protein sequence.
The epitopic mapping on cellulose membrane was performed according to Ronald Frank (Frank, R. 1992 Tetrahedron 48: 9217-9232). The serum samples were assayed at a 1/100 dilution.
Results of facing the sera from the mice inoculated with the normal antigen and the different aggregated variants of the same antigen, evidenced that there is no a similar linear recognition pattern between both antigens, which leads to the conclusion that a different presentation is produced for the B epitopes present on the surface of HBsAg and its aggregated variants (figure
Example 9. Formation of aggregates between HBsAg and nucleocapsid
antigens. Immunological assessment.
Equal volumes of two preparations containing 0.1 mg/mL HBsAg and HBcAg were incubated at 4°C overnight and afterwards aggregates were obtained by HPLC TSK G6000 molecular exclusion chromatography. A sample of these aggregates was processed for electron microscopy visualization techniques, the other sample was used for its immunological evaluation with an immunization schedule in Balb/C mice by intranasal inoculation, with both antigens separately and with the aggregate verified by electron microscopy (Fig. 5A).
Results evidenced that the mixture of both aggregated antigens by intranasal route allowed the potentiation of the response against the HBsAg (Fig SB). The groups of the figure are represented in the following table:
1 -10 ^g HBsAg/ PBS 1X IN
2-10 \ig HBsAg/ acemannan 3 mg/mL IN
3-10 ^ig HBsAg/ 10ng HBcAg / PBS 1X IN
4-10p.g HBsAg/Alum 0.5 mg/mL SC
Similar results were obtained when other viral capsid antigens such as hepatitis C and HIV were used to prepare the mixture.
BRIEF DESCRIPTION OF THE DRAWINGS
(A) Three dose schedule (0, 2 y 4 weeks). The extractions were performed
the week 6. The three first groups were inoculated with 50 M-L by intranasal
route. The two remaining groups were inoculated by intramuscular route in
alum with 100 |aL
(B) Aggregated HBsAg. (meter: 200nm)
Three dose schedule (0, 2 y 18 weeks). All groups were inoculated by intramuscular route with a volume of 100 |j.L. The antibody values correspond to the week 8 (fig. 2a). During the week 22 se the DTH test was performed. Figure 2b represents the DTH value for groups 1 and 3 during 5 days. Figure 2c represents the kinetics of increase of liters during the schedule.
The same 3 doses schedule (0, 2 y 4 weeks) of figure 1. Analysis of groups D and E sera from the week 6 extraction. Both groups were inoculated by intramuscular route in alum with 100 nL, group D with delipidated HBsAg (50-500 nm) and group E with normal HBsAg with the same doses. In the graph it is represented the geometric mean value and interval of the lgG1/lgG2a ratio for each mouse of both groups. Figure 4.
Mapping of overlapping peptides of the S region of HBsAg on cellulose membrane containing linear sequences. 1/100 dilutions of sera pools were analyzed: 1, HBsAg (normal); 2, HBsAg (aggregated); (3-5: monoclonal antibodies (MAbs) obtained immunizing with aggregated antigens; 3, clone 6; 4, done 7; 5, clone 8); 6, non related serum; 7, MAb (Hep 1). Four color intensities represent the response against the peptides. Blank: negative response, clear gray: slightly positive response, dark gray: positive response, black: very positive response. Figure 5.
(A) Electron microscopy of HBsAg aggregates and HBcAg, the higher
electron-dense particles in the center mayor corresponds to HBcAg, the other
(B) 2 dose schedule (0,14 days). Analysis of sera the day 26.
1. An aggregated antigenic structure obtained by a process comprising the steps:
a) selecting an antigen from HBs Ag, HBc Ag, Picchis pastoris, such as herein described;
b) adding one or several antigens as a mixture in a medium which favors the aggregation process such as chemical or oxidizing or other components with aggregating capacity;
c) incubating the mixture;
d) selecting 30 to 500 nm size particle aggregates through a process which permits the retention of those molecular sizes preferably molecular exclusion chromatography, diafiltration and dialysis; and
e) optionally adding adjuvant selected from other antigens, stabilizing and
preserving substances and one, two or more hydrophobic particles as herein
2. An aggregated antigenic structure as claimed in claim 1, wherein the antigen of interest is a lipoprotein, lipopeptide or lipidic homologous or heterologous antigens or hydrophobic particulated antigens.
3. Aggregated antigenic structure obtained as claimed in claim 1, containing aggregated structures with a size ranges from 50-500 nm.
4. Aggregated antigenic structure obtained as claimed in claim 1, wherein the adjuvants are alum or calcium salts.
5. Aggregated antigenic structure obtained as claimed in claim 1. wherein the aggregating agents are selected from the group of (3-cyclodextrins, ammonia salts, metal salts of copper and iron.
|Indian Patent Application Number||3306/DELNP/2004|
|PG Journal Number||31/2008|
|Date of Filing||26-Oct-2004|
|Name of Patentee||CENTRO DE INGENIERIA GENETICA Y BIOTECNOLOGIA|
|Applicant Address||AVE. 31, ENTRE 158 Y 190, CUBANACAN, PLAYA, C.HABANA 12100, CUBA.|
|PCT International Classification Number||A61K 39/29|
|PCT International Application Number||PCT/CU01/00009|
|PCT International Filing date||2001-11-29|