Patent Application
20090104223
1. 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.
2. 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 K H, Gerlich W H, 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, D R. 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 T cells. It was evidenced that an efficient 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 μm 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, R N. 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 μm 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 μm 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% 1,1′,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 A R 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 of chaotropic 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 al. 1998 J Chromatogr B Biomed Sci Appl 25; 716(1-2); 209-19).
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 antigens, stabilizers and preservatives.
Several aggregates that only contain the surface antigen of the HBV may be obtained by the present invention method, including also combinations of the surface antigen and other lipoprotein, lipopeptide or lipidic homologous or heterologous antigens from any viral, bacterial, unicellular or multicellular pathogen.
According to the invention method the antigens that are part of the structures obtained in the step (B) may be added to the surface antigen of the hepatitis B virus by hydrophobic, electrostatic or covalent interactions, generating aggregates of different sizes.
The method to obtain antigenic structures allows the aggregation of the hepatitis B, C or HIV nucleocapsid antigens to the hepatitis B virus surface antigen, also antigens from virus and bacteria such as inactivated virus or outer membrane proteins of bacterial pathogens like Neisseria meningitidis, may be aggregated.
To obtain the aggregated antigenic structures β-cyclodextrins may be used as chemical agent favoring delipidation, membrane association and aggregation of the present particles, other chemical agents are ammonia salts at concentrations between 10 and 50 mM, potentiated by metal salts of copper and iron and others permitting aggregation.
Other components of the method presenting spontaneous aggregating activity that may be used together or alone for this purpose are the homologous or heterologous antigens that evidenced aggregating activity on HBsAg, among them the viral nucleocapsid antigens and also bacterial outer membrane derivatives or viral envelopes of lipoprotein or hydrophobic nature. It was also found that adjuvants of the same nature favored HBsAg aggregation and that of HBsAg with themselves.
In general the present invention method allows HBsAg aggregation or the HBsAg aggregation with other antigens or adjuvants through the development of hydrophobic interactions, electrostatic or covalent linkages, with incubation periods ranking from 10 minutes to one week, depending on the selected constituents.
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 al. 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 IgG2a 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.
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 β-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.
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.
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:
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.
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 immunized 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
The statistical analysis of results was performed by the Student test and p<0.05 was considered a significant difference.
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:
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:
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<0.05 se was considered a significant difference.
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
With the objective of studying if a variation in the IgG1/IgG2a 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 IgG2a antibody levels. This analysis was performed for the sera of the day 42 extraction. The IgG2a antibody levels increased significantly in the group immunized with the over-particulated antigen (50-500 nm) up to attaining an IgG1/IgG2a ratio closer to 1 as compared to the normal HBsAg also adjuvanted in alum (
The IgG1/2a 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.
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.
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 (
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 (
Results evidenced that the mixture of both aggregated antigens by intranasal route allowed the potentiation of the response against the HBsAg (
Similar results were obtained when other viral capsid antigens such as hepatitis C and HIV were used to prepare the mixture.
(A) Three dose schedule (0, 2 y 4 weeks). The extractions were performed the week 6. The three first groups were inoculated with 50 μL by intranasal route. The two remaining groups were inoculated by intramuscular route in alum with 100 μL.
(B) Aggregated HBsAg. (meter: 200 nm)
Three dose schedule (0, 2 y 18 weeks). All groups were inoculated by intramuscular route with a volume of 100 μL. The antibody values correspond to the week 8 (
The same 3 doses schedule (0, 2 y 4 weeks) of
Mapping of overlapping peptides (SEQ. ID. NOS: 1-37) 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, clone 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.
(A) Electron microscopy of HBsAg aggregates and HBcAg, the higher electron-dense particles in the center mayor corresponds to HBcAg, the other are HBsAg.
(B) 2 dose schedule (0, 14 days). Analysis of sera the day 26.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2972000 | Dec 2000 | CU | national |
The present application is a divisional of application Ser. No. 10/433,492 filed on Mar. 1, 2004, which is a U.S. National Phase Application of International Application No. PCT/CU01/00009 filed on Nov. 29, 2001, which asserts priority to Cuban Application No. 297/2000 filed on Dec. 1, 2000. The foregoing applications are hereby incorporated by reference herein. Incorporated herein by reference in its entirety is the Sequence Listing for the application. The Sequence Listing is disclosed on a computer-readable ASCII text file titled, “sequence_listing.txt”, created on Oct. 10, 2007. The sequence_listing.txt file is 9 kb in size.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10433492 | Mar 2004 | US |
| Child | 11870088 | US |
