IMMUNOLOGICAL CHARACTERISTIC OF SYNTHETIC PEPTIDES SIMILAR TO ACTUAL HIV ANTIGEN DETERMINANTS

The development of HIV vaccine remains an important goal in prophylaxis and therapy of HIV/ AIDS epidemics. There are various approaches for development of а candidate vaccine based on induction of neutralizing antibodies and cell-mediated immunity. Synthetic peptides are considered promising vaccine antigens since they are capable of activating both humoral and cellular immune response. HIV-1 envelope gp120 is the target for neutralizing antiviral antibodies. The V3 region of the HIV-1 gp120 is highly immunogenic and important for the virus-coreceptor interaction. In a RV144 vaccine trial, the levels of vaccine-induced IgG antibodies recognizing V1V2 regions from multiple HIV-1 subtypes show inverse correlations with a risk for HIV-1 infection. Meanwhile, HIV is characterized by high diversity. The consensus and mosaic immunogens are complete but artificial proteins, which are computationally designed to elicit immune responses with improved cross-reactive broadness. We have been studied immunogenic properties of synthetic peptides derived from V1, V2, V3 loop regions of the consensus M HIV1 (CON-S) sequence group of the gp 120 envelope protein and V3 loop derived from a Russian RUA022a2 isolate. These peptides specifically reacted to HIV-positive sera in ELISA, thus indicating their similarity to appropriate HIV proteins. The peptides proved to be weakly immunogenic. Therefore, Freund complete adjuvant was used to enhance peptide immunogenicity. To assess the immunogenicity, the mice were immunized with a peptide mixture. Antibodies have been developed to every peptide from the mixture, being, predominantly, of IgG isotype. The antibody titers depended on the length of peptide sequences. However, the sera from immunized mice did not have a HIV neutralizing activity. The serum neutralization was assessed by pseudovirus-based assay, using a molecular clone of virus isolates CAP 45.2.00.G3 and QH.209.14.M.EnvA2. The virus neutralization is a complex process and may be influenced by several factors, such as antibody titer, isotype, or antibody structure. Probably, to induce neutralizing antibodies by this peptide mixture, it is necessary to choose appropriate adjutants and immunization schedule. Moreover, it was shown that peptides could increase in vitro virus infectivity in pseudovirus-based model, using the CAP 45.2.00.G3, QH209.14M.ENV.A2, QD435.100M.ENV.E1 molecular clone. These viral isolates belong to different HIV-1 subtypes.

HIV, peptides, vaccine, neutralizing antibodies, mice, infection enhancement

1. Chavez L., Calvanese V., Verdin E. HIV Latency Is Established Directly and Early in Both Resting and Activated Primary CD4 T Cells. Plos Pathog., 2015, Vol. 11, no. 6, e1004955.

2. Duerr A., Huang Y., Buchbinder S., Coombs R.W., Sanchez J., del Rio C., Casapia M., Santiago S., Gilbert P., Corey L., Robertson M.N. Extended follow-up confirms early vaccine-enhanced risk of HIV acquisition and demonstrates waning effect over time among participants in a randomized trial of recombinant adenovirus HIV vaccine (Step Study). J. Infect. Dis., 2012, Vol. 206, no. 2, pp. 258-266.

3. Dettin M., Scarinci C., Zanotto C., Roncon R., De Rossi A., Di Bello C. Biological and conformational studies on analogues of a synthetic peptide enhancing HIV-1 infection. J. Pept. Sci., 1998, Vol. 4, no. 7, pp. 436-448.

4. Deng H., Liu R., Ellmeier W., Choe S., Unutmaz D., Burkhart M., Di Marzio P., Marmon S., Sutton R.E., Hill C.M., Davis C.B., Peiper S.C., Schall T.J., Littman D.R., Landau N.R. Identification of a major co-receptor for primary isolates of HIV-1. Nature, 1996, Vol. 381, pp. 661-666.

5. Díez-Fuertes F., Cabello M., Thomson M.M. Bayesian phylogeographic analyses clarify the origin of the HIV-1 subtype A variant circulating in former Soviet Union’s countries. Infect. Genet. Evol. 2015, pii: S1567-1348(15)00165-3.

6. Edlefsen P.T., Rolland M., Hertz T., Tovanabutra S., Gartland A.J., deCamp A.C., Magaret C.A., Ahmed H., Gottardo R., Juraska M., McCoy C., Larsen B.B.,Sanders-Buell E., Carrico C., Menis S., Bose M., Arroyo M.A., O’Connell R.J., Nitayaphan S., Pitisuttithum P., Kaewkungwal J., Rerks-Ngarm S., Robb M.L., Kirys T., Georgiev I.S., Kwong P.D., Scheffler K., Pond S.L., Carlson J.M., Michael N.L., Schief W.R., Mullins J.I., Kim J.H., Gilbert P.B. Comprehensive sieve analysis of breakthrough HIV-1 sequences in the RV144 vaccine efficacy trial. PLoS Comput. Biol., 2015, Vol. 11, no. 2, e.1003973.

7. Haynes B.F., Gilbert P.B., McElrath M.J., Zolla-Pazner S., Tomaras G.D., Alam S.M., Evans D.T., Montefiori D.C., Karnasuta C., Sutthent R., Liao H.X., DeVico A.L., Lewis G.K., Williams C., Pinter A., Fong Y., Janes H., DeCamp A., Huang Y., Rao M., Billings E., Karasavvas N., Robb M.L., Ngauy V., de Souza M.S., Paris R., Ferrari G., Bailer R.T., Soderberg K.A., Andrews C., Berman P.W., Frahm N., De Rosa S.C., Alpert M.D., Yates N.L., Shen X., Koup R.A., Pitisuttithum P., Kaewkungwal J., Nitayaphan S., Rerks-Ngarm S., Michael N.L., Kim J.H. Immune-correlates analysis of an HIV-1 vaccine efficacy trial. N. Engl. J. Med., 2012., Vol. 366, pp. 1275-1286.

8. Henrich T.J., Kuritzkes D.R. HIV-1 entry inhibitors: recent development and clinical use. Curr. Opin. Virol., 2013, Vol. 3, no. 1, pp. 51-77.

9. Julien J.P., Sok D., Khayat R., Lee J.H., Doores K.J., Walker L.M., Ramos A., Diwanji D.C., Pejchal R., Cupo A., Katpally U., Depetris R.S., Stanfield R.L., McBride R., Marozsan A.J., Paulson J.C., Sanders R.W., Moore J.P., Burton D.R., Poignard P., Ward A.B., Wilson I.A. Broadly neutralizing antibody PGT121 allosterically modulates CD4 binding via recognition of the HIV-1 gp120 V3 base and multiple surrounding glycans. PLoS Pathog., 2013, Vol. 9, no. 5, e1003342.

10. Liao H.X., Sutherland L.L., Xia S.M., Brock M.E., Scearce R.M., Vanleeuwen S., Alam S.M., McAdams M., Weaver E.A., Camacho Z., Ma B.J., Li Y., Decker J.M., Nabel G.J., Montefiori D.C., Hahn B.H., Korber B.T., Gao F., Haynes B.F. A group M consensus envelope glycoprotein induces antibodies that neutralize subsets of subtype B and C HIV-1 primary viruses. Virology, 2006, Vol. 353, no. 2, pp. 268-282.

11. Montefiori D.C. Measuring HIV neutralization in a luciferase reporter gene assay. Methods Mol. Biol., 2009, Vol. 485, pp. 395-405.

12. Peeters M., D’Arc M., Delaporte E. Origin and diversity of human retroviruses. AIDS Rev., 2014, Vol. 16, no. 1, pp. 23-34.

13. Sarzotti-Kelsoe M., Bailer R.T., Turk E., Lin C.L., Bilska M., Greene K.M., Gao H., Todd C.A., Ozaki D.A., Seaman M.S., Mascola J.R., Montefiori D.C. Optimization and validation of the TZM-bl assay for standardized assessments of neutralizing antibodies against HIV-1. J. Immunol. Methods, 2014, Vol. 409, pp. 131-146.

14. Sagar M., Wu X., Lee S., Overbaugh J. Human immunodeficiency virus type 1 V1-V2 envelope loop sequences expand and add glycosylation sites over the course of infection, and these modifications affect antibody neutralization sensitivity. J. Virol., 2006, Vol. 80, no. 19, pp. 9586-9598.

15. Tomaras G.D., Haynes B.F. Strategies for eliciting HIV-1 inhibitory antibodies. Curr. Opin. HIV AIDS, 2010, Vol. 5, no. 5, pp. 421-427.

16. Trkola A., Purtscher M., Muster T., Ballaun C., Buchacher A., Sullivan N., Srinivasan K., Sodroski J., Moore J.P., Katinger H. Human monoclonal antibody 2G12 defines a distinctive neutralization epitope on the gp120 glycoprotein of human immunodeficiency virus type 1. J. Virol., 1996, Vol. 70, no. 2, pp. 1100-1108.

17. Watkins J.D., Siddappa N.B., Lakhashe S.K., Humbert M., Sholukh A., Hemashettar G., Wong Y.L., Yoon J.K., Wang W., Novembre F.J., Villinger F., Ibegbu C., Patel K., Corti D., Agatic G., Vanzetta F., Bianchi S., Heeney J.L., Sallusto F., Lanzavecchia A., Ruprecht R.M. An anti-HIV-1 V3 loop antibody fully protects cross-clade and elicits T-cell immunity in macaques mucosally challenged with an R5 clade C SHIV. PLoS One, 2011,Vol. 6, no. 3, e18207.

18. Yates N.L., Liao H.X., Fong Y., deCamp A., Vandergrift N.A.,Williams W.T.,Alam S.M., Ferrari G.,Yang Z.Y., Seaton K.E., Berman P.W., Alpert M.D., Evans D.T., O’Connell R.J., Francis D., Sinangil F., Lee C., Nitayaphan S., Rerks-Ngarm S., Kaewkungwal J., Pitisuttithum P., Tartaglia J., Pinter A., Zolla-Pazner S., Gilbert P.B., Nabel G.J., Michael N.L., Kim J.H., Montefiori D.C., Haynes B.F., Tomaras G.D. Vaccine-induced Env V1–V2 IgG3 correlates with lower HIV-1 infection risk and declines soon after vaccination. Sci. Transl. Med., 2014, Sci. Transl. Med., Vol. 6, no. 228, p. 228ra39.

19. Zanotto C., Calderazzo F., Dettin M., Di Bello C., Autiero M., Guardiola J., Chieco-Bianchi L., De Rossi A. Minimal sequence requirements for synthetic peptides derived from the V3 loop of the human immunodeficiency virus type 1 (HIV-1) to enhance HIV-1 binding to cells and infection. Virology, 1995, Vol. 206, no. 2, pp. 807-816.

20. Zolla-Pazner S., deCamp A., Gilbert P.B., Williams C., Yates N.L., Williams W.T., Howington R., Fong Y., Morris D.E., Soderberg K.A., Irene C., Reichman C., Pinter A., Parks R., Pitisuttithum P., Kaewkungwal J., RerksNgarm S., Nitayaphan S., Andrews C., O’Connell R.J., Yang Z.Y., Nabel G.J., Kim J.H., Michael N.L., Montefiori D.C., Liao H.X., Haynes B.F., Tomaras G.D. Vaccine-induced IgG antibodies to V1V2 regions of multiple HIV-1 subtypes correlate with decreased risk of HIV-1 infection. PLoS One, 2014, Vol. 9, no. 2, e87572.

21. Zolla-Pazner S. Identifying epitopes of HIV-1 that induce protective antibodies. Nat. Rev. Immunol., 2004, Vol. 4, no. 3, pp. 199-210.