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Differences of immune Env-specific responses between newly EIAV infected and inapparent carrier horses

Sonia Ricotti1, María V. Barcarolo1, María I. Garcia1 and Adriana R. Soutullo1, 2*
  • 1 Universidad Nacional del Litoral, Facultad de Bioquímica y Ciencias Biologicas, Argentina
  • 2 Ministerio de la Produccion, Sub Dirección de Ganadería y Sanidad Animal, Argentina

Unlike other lentiviruses, EIAV replication can be eventually controlled in most infected horses leading to an inapparent carrier state free of overt clinical signs. Maintenance of this carrier state is absolutely dependent on active immune responses and probably this could be extremely related with the appearance of virus specific immune response during early stage of infection. Since the virus undergoes rapid mutation following infection, the immune response must also adapt to meet this challenge. Nevertheless, more studies should be focalized in conserved regions, especially in viral enveloped proteins. Indeed, few studies have examined the cellular and humoral immune responses to the viral antigens throughout natural infection. Thus, the goal of the current study is to determine if native conserved sequences within viral glycoproteins of EIAV may induce humoral and cellular immune response from early to latent stages of natural infection. To that purpose, we analyzed 10 newly infected horses, 28 inapparent carriers and 12 EIAV uninfected (control) horses. Four synthetic peptides, gp90-A(416-444)/B(118-149) and gp45-A(522-546)/B(651-670), representing conserved regions in envelope proteins, were used to find the peptide-specific antibodies by ELISA and T cell responses by lymphoproliferation in vitro. To evaluate if memory T cells are CD4+ or CD8+ cells, lymphoproliferation assays were performed with prior blocking using anti-MHC II or anti-MHC I specific monoclonal antibodies, respectively. Mann Whitney and Kruskal–Wallis tests were used to compare data and statistical significance of differences was defined at P < 0.05. The results showed that 9/10 (90%) and 28/28 (100%) of newly infected and inapparent carrier horses respectively, had antiviral antibodies against at least one of the four regions studied, corresponding to EIAV envelope glycoproteins. Indeed, the majority of naturally infected horses had antibodies to gp90-A(416-444); gp45-A(522-546) and gp45-B(651-670), being their levels superior during carrier stage. By contrast, no antibody against gp90-B(118-149) could be detected in recently infected horses. Only four newly infected horses had lymphocytes capable of recognizing at least one synthetic peptide, being peptide gp90-B(118-149), the most recognized one, in spite of the fact that no specific antibodies were found. By contrast, we have detected proliferation of effector/memory T cells with at least one peptide in the most carrier horses, being gp90-A(416-444) the synthetic peptide more recognized. Our results indicated that these viral conserved sequences, like these synthetic peptides studied, may represent T and B epitopes from early to latent stages of natural infection. If this is so, it is vital to define other conserved regions during natural infection in order to incorporate all of them as candidate vaccine molecules.

References

Bailat, A.S., et al., 2008. Effect of two synthetic peptides mimicking conserved regions of Equine Infectious Anemia Virus proteins gp90 and gp45 upon cytokine mRNA expression. Arch. Virol. 153, 1909–1915.
Ball, J.M., et al., 1992. Detailed Mapping of the Antigenicity of the Surface Unit Glicoprotein of Equine Infectious Anemia Virus by Using Synthetic Peptide Strategies. J. Virol. 66, 732-742.
Bansal, A., et al., 2005. CD8 T-cell responses in early HIV-1 infection are skewed towards high entropy peptides. Aids. 19, 241-250.
Bar, K.J., et al., 2010. Molecular targets and potency of HIV-1 neutralization revealed by dynamic assessment of transmitted/founder virus antibody recognition and escape. Aids Res Human Retrov. 26, 11–12.
Chong, Y.H., et al., 1991. Analysis of equine humoral immune responses to the transmembrane envelope glycoprotein (gp45) of Equine Infectious Anemia Virus. J. Virol. 65, 1013-1018.
Clabough, D.L., et al., 1991. Immune-mediated thrombocytopenia in horses infected with equine infectious anemia virus. J. Virol. 65, 6242–6251.
Cook, R.F., et al., 2013. Equine infectious anemia and Equine Infectious Anemia Virus in 2013: A review. Vet. Microbiol. 167, 181–204.
Craigo, J.K., et al., 2007a. Immune suppression of challenged vaccinates as a rigorous assessment of sterile protection by lentiviral vaccines. Vaccine. 25, 834-845.
Craigo, J.K., et al., 2007b. Envelope variation as a primary determinant of lentiviral vaccine efficacy. Proc. Natl. Acad. Sci. USA. 104, 15105–15110.
Craigo, J.K., et al., 2010. Divergence, not diversity of an attenuated equine lentivirus vaccine strain correlates with protection from disease. Vaccine. 28, 8095–8104.
Craigo, J.K., et al., 2013a. Lessons in AIDS Vaccine Development Learned from Studies of Equine Infectious, Anemia Virus Infection and Immunity. Viruses. 5, 2963-2976.
Craigo, J.K., et al., 2013b. Envelope Determinants of Equine Lentiviral Vaccine Protection. PLoS ONE 8(6):e66093. doi:10.1371/journal.pone.0066093. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0066093.
Engvall, E., et al., 1972. Enzyme-linked immunoadsorbent assay (ELISA): quantitative assay of immunoglobulin G. Immunochemistry. 8, 871-879.
Flint, S.J., et al., 2000. Principles of virology molecular biology, pathogenesis, and control. Virus entry into cells. ASM Press. Washington, DC, 133-161.
Fraser, D.G., et al., 2002. Identification of broadly recognized, T helper 1 lymphocyte epitopes in an equine lentivirus. Immunol. 105, 295–305.
Gallimore, A., et al., 1998. Induction and exhaustion of lymphocytic choriomeningitis virus-specific cytotoxic T lymphocytes visualized using soluble tetrameric major histocompatibility complex class I-peptide complexes. J. Exp. Med. 187, 1383-1393.
Goulder, P.J., et al., 2001. Substantial differences in specificity of HIV-specific cytotoxic T cells in acute and chronic HIV infection. J. Exp. Med. 193, 181-194.
Hammond, S.A., et al., 2000. Immune responses and viral replication in long-term inapparent carrier ponies inoculated with equine infectious anemia virus. J. Virol. 74, 5968–5981.
Harrold, S.M., et al., 2000. Tissue sites of persistent infection and active replication of equine infectious anemia virus during acute disease and asymptomatic infection in experimentally infected equids. J. Virol. 74, 3112–3121.
Henzi, J.E., et al., 2013. Pushing the endogenous envelope. Phil. Trans. R. Soc. B. 368, 20120506.
Herbein, G., et al., 1998. Apoptosis of CD8+ T cells is mediated by macrophages through interaction of HIV gp120 with chemokine receptor CXCR4. Nature. 395, 189-194.
Hussain, K.A., et al., 1988. Antigenic mapping of the envelope proteins of Equine Infectious Anemia Virus: identification of a neutralization domain and a conserved region on glycoprotein 90. Arch. Virol. 98, 213-224.
Issel, C.J., et al., 1979. Equine infectious anemia: current knowledge. J. Am. Vet. Med. Assoc. 174, 727–733.
Kono, Y., et al., 1976. Recrudesence of equine infectious anemia by treatment with immunosuppressive drugs. Nat. Inst. Anim. Hlth. Quart. 16, 8-15.
Liu, J., et al., 2008. Molecular architecture of native HIV-1 gp120 trimers. Nature. 455, 109–113.
Liu, C., et al., 2012. The determination of in vivo envelope-specific cell-mediated immune responses in Equine Infectious Anemia Virus-infected ponies. Vet. Immunol. Immunopathol. 148, 302-310.
Liu, C., et al., 2014. Epitope shifting of gp90-specific cellular immune responses in EIAV-infected ponies. Vet. Immunol. Immunopathol. 161, 161-169.
MacLachlan, N.J., et al., 2011. Equine Infectious Anemia Virus (Retroviridae). Fenner’s Veterinary Virology, 4th edn, Elsevier, pp. 269– 270.
McGuire, T.C., et al., 2000. Equine Infectious Anemia Virus proteins with epitopes most frequently recognized by cytotoxic T lymphocytes from infected horses. J. Gen. Virol. 81, 2735-2739.
McGuire, T.C., et al., 2003. Presentation and binding affinity of Equine Infectious Anemia Virus CTL envelope and matrix protein epitopes by an expressed equine classical MHC Class I Molecule. J. Immunol. 171, 1984-1993.
Mealey, R.H., et al., 2001. Immune reconstitution prevents continuous Equine Infectious Anemia Virus replication in an Arabian foal with severe combined immunodeficiency: lessons for control of lentiviruses. Clin. Immunol. 101, 237–247.
Mealey, R.H., et al., 2003. Epitope specificity is critical for high and moderate avidity cytotoxic T lymphocytes associated with control of viral load and clinical disease in horses with Equine Infectious Anemia Virus. Virology. 313, 537-552.
Mealey, R.H., et al., 2004. Adaptive immunity is the primary force driving selection of Equine Infectious Anemia Virus envelope SU variants during acute infection. J. Virol. 78, 9295-9305.
Mealey, R.H., et al., 2005. Early detection of dominant Env-specific and subdominant gag-specific CD8+ lymphocytes in Equine Infectious Anemia Virus -infected horses using major histocompatibility complex class I/peptide tetrameric complexes. Virology. 339, 110-126.
Montelaro, R.C., et al., 1984. Antigenic reactivity of the major glycoprotein of equine infectious anemia virus, a retrovirus. Virology. 136, 368- 374.
Montelaro, R.C., et al., 1993. Equine retrovirus. The Retroviridae, vol. 2. Plenum Press, New York, pp. 257–359.
O´Rourke, K., et al., 1988. Antiviral antiglicoprotein and neutralizing antibodies in foals with Equine Infectious Anaemia Virus. J. Gen. Virol. 69, 667- 674.
Payne, S.L., et al., 1989. Localization of conserved and variable antigenic domains of Equine Infectious Anemia Virus envelope glycoproteins using recombinant env-encoded protein fragments produced in Escherichia coli. Virology. 172, 609-615.
Perryman, L.E., et al., 1988. Immune responses are required to terminate viremia in equine infectious anemia lentivirus infection. J. Virol. 62, 3073–3076.
Perryman, L.E., et al., 1990. Equine monoclonal antibodies recognize common epitopes on variants of Equine Infectious Anaemia Virus. Immunol. 71, 592- 594.
Rwambo, P.M., et al., 1990. Equine Infectious Anemia Virus (EIAV) humoral responses of recipient ponies and antigenic variation during persistent infection. Arch. Virol. 111, 199-212.
Sellon, D.C., et al., 1994. The immunopathogenesis of Equine Infectious Anemia Virus. Virus. Res. 32, 111–138.
Shearer, G.M., 1998. HIV-induced immunopathogenesis. Immunity. 9, 587-593.
Shively, M.A., et al., 1982. Antigenic stimulation of T-Lymphocytes in chronic nononcogenic Retrovirus infection: Equine Infectious Anemia. Infect. Immun. 36, 38-46.
Soutullo, A., et al., 2001. Design and validation of an ELISA for equine infectious anemia (EIA) diagnosis using synthetic peptides. Vet. Microbiol. 79, 111-121.
Soutullo, A., et al., 2005. Antibodies and PBMC from EIAV infected carrier horses recognize gp45 and p26 synthetic peptides. Vet. Immunol. Immunopathol. 108, 335-343.
Soutullo, A., 2008. Estudio de la capacidad antigénica e inmunogénica de péptidos sintéticos correspondientes a epitopes conservados de las proteínas estructurales del Virus de la Anemia Infecciosa Equina. http://bibliotecavirtual.unl.edu.ar:8180/tesis/handle/1/55.
Sun, C.Q., et al., 2008. Binding of equine infectious anemia virus to the equine lentivirus receptor-1 is mediated by complex discontinuous sequences in the viral envelope gp90 protein. J. Gen. Virol. 89, 2011–2019.
Tagmyer, T.L., et al., 2007. Envelope-specific T-helper and cytotoxic Tlymphocyte responses associated with protective immunity to equine infectious anemia virus. J. Gen. Virol. 88, 1324–1336.
Tagmyer, T.L., et al., 2008. Envelope determinants of Equine Infectious Anemia Virus vaccine protection and the effects of sequence variation on immune recognition. J. Virol. 82 (8), 4052-4063.
Wang, J.D.X., et al., 2014. Structural and biochemical insights into the V/I505T mutation found in the EIAV gp45 vaccine strain. Retrovirology. 11, 26.
Wei, X.P., et al., 2003. Antibody neutralization and escape by HIV-1. Nature. 422, 307–312.
Zhang, B., et al., 2005. A tumor necrosis factor receptor family protein serves as a cellular receptor for the macrophagetropic equine lentivirus. P. Natl. Acad. Sci. USA. 102, 9918–9923.
Zhang, B., et al., 2008. Mapping of Equine Lentivirus Receptor 1 Residues Critical for Equine Infectious Anemia Virus Envelope Binding. J. Virol. 82, 1204–1213.

Keywords: EIAV-naturally infected horses, Glycoproteins, synthetic peptides, Antigenicity, T/B epitopes

Conference: IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología, Medellin, Colombia, 13 Oct - 16 Oct, 2015.

Presentation Type: Poster Presentation

Topic: Veterinary and Comparative Immunology

Citation: Ricotti S, Barcarolo MV, Garcia MI and Soutullo AR (2015). Differences of immune Env-specific responses between newly EIAV infected and inapparent carrier horses. Front. Immunol. Conference Abstract: IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología. doi: 10.3389/conf.fimmu.2015.05.00239

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Received: 13 Apr 2015; Published Online: 14 Sep 2015.

* Correspondence: Dr. Adriana R Soutullo, Ministerio de la Produccion, Sub Dirección de Ganadería y Sanidad Animal, Santa Fe, International/Other, 3000, Argentina, adrianasoutullo@gmail.com