(31.2%) against HIV infection observed in the RV144 Thai clinical trial highlighted the need to develop novel improved poxvirus-based recombinants. Methods: ...
P10.06 CD8 T-cell Based HIV Vaccines - Is Targeting Conserved Epitopes the Answer? Shelby L. O’Connor, Dane Gellerup, Max Harris, Ericka Becker University of Wisconsin-Madison, Madison, WI, United States Background: Immunodominant CD8 T cell responses emerge in the first few weeks after HIV/SIV infection, suppress virus replication, and select for escape variants. Although T-cell based HIV vaccines have not successfully provided sterilizing immunity, vaccine-elicited CD8 T cells may contribute to the control of replication of breakthrough viruses. It is critical that a T-cell based vaccine generates an effective pool of memory CD8 T cells that are available to respond during acute HIV infection and effectively control both acute and chronic virus replication. Designing a vaccine to elicit these potent CD8 T cells in all vaccinated individuals, however, is a daunting challenge. Conceptually, a vaccine that elicits CD8 T cell responses targeting highly conserved virus peptide sequences would have the most widespread impact, but the efficacy of T cells targeting these conserved epitopes is unknown. Methods: We employ a model of SIVmac239Dnef-infected MHC-identical Mauritian cynomolgus macaques to test the hypothesis that CD8 T cells targeting conserved epitopes are unable to detect and destroy virally infected cells. Accordingly, we expect that CD8 T cells targeting epitopes that accumulate variants are more effective at controlling virus replication. To test this hypothesis, we are creating variants of live attenuated SIVmac239Dnef designed to elicit CD8 T cells targeting epitopes that do and do not accumulate variants. Results: We will determine whether the mutant viruses are ‘fit’ and whether the included variant epitope sequences are no longer detected by CD8 T cells. In the future, we will determine if acute CD8 T cells targeting these different categories of epitopes are able to control virus replication, in vivo. Conclusions: The conclusions from this study will help identify whether CD8 T cells that develop during acute HIV infection can be specific for highly conserved epitopes and whether they can control virus replication.
P10.07 Bivalent NYVAC-based Vaccine Candidates against HIV/AIDS Expressing Clade C Trimeric Soluble gp140(ZM96) and Gag(ZM96)-Pol-Nef(CN54) as VLPs Beatriz Perdiguero1, Carmen Elena Go´mez1, Marı´a Victoria Cepeda1, Lucas Sa´nchez-Sampedro1, Juan Garcı´a-Arriaza1, Ernesto Mejı´as-Pe´rez1, Victoria Jime´nez1, Cristina Sa´nchez1, Carlos Oscar S. Sorzano1, Julie Delaloye2, Thierry Roger2, Thierry Calandra2, Ralf Wagner3, Benedikt Asbach3, Karen V. Kibler4, Bertram L Jacobs4, Giuseppe Pantaleo2, Mariano Esteban1 1
Centro Nacional de Biotecnologı´a, CNB-CSIC, Madrid, Spain, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, 3University of Regensburg, Regensburg, Germany, 4The Biodesign Institute at Arizona State University, Tempe, AZ, United States 2
Background: The generation of vaccine candidates against HIV/AIDS able to induce long-lasting protective immunity remains a major goal in the HIV field. The reduced efficacy (31.2%) against HIV infection observed in the RV144 Thai
clinical trial highlighted the need to develop novel improved poxvirus-based recombinants. Methods: In the present study, we have generated two novel NYVAC vectors expressing HIV-1 clade C gp140(ZM96) (NYVAC-gp140) or Gag(ZM96)-Pol-Nef(CN54) (NYVACGag-Pol-Nef) and defined their biological characteristics in cultured cells and in mice. Results: Insertion of the HIV-1 genes in the viral genome does not affect the replication capacity of the NYVAC recombinants in primary chick cells and the HIV-1 antigens are correctly expressed and released from the cells, with Env protein as a trimer (NYVACgp140), while in cells infected with NYVAC-Gag-Pol-Nef, Gaginduced VLPs are abundant. Electron microscopy revealed that VLPs are accumulated with time at the cell surface, with no interference with NYVAC morphogenesis. Gag-Pol-Nef expression in human primary monocytes markedly increases the levels of immunomodulatory molecules, such as cytokines and chemokines. Both recombinant viruses show an attenuation profile in immunocompromised BALB/c mice after intracranial inoculation. Analysis of the immune responses elicited in mice after homologous NYVAC prime/NYVAC boost immunization shows that the two recombinant viruses induced polyfunctional Env-specific CD4 or Gag-specific CD8 T cell immune responses. Antibody responses against gp140 and p17/p24 were also elicited by both NYVAC vectors. Conclusions: Our findings showed that bivalent NYVAC vectors can be considered as candidate vaccines against HIV/AIDS.
P10.08 Characterization of the Binding Affinity of Siglec-1 to gp120, gp145, and V2 Loop via Sialic Acid Binding Motif Hung V. Trinh1, Ousman Jobe1, Guofen Gao2, Carl R. Alving3, Venigalla Rao2, Mangala Rao3 1
U.S. Military HIV Research Program (MHRP)/HJF, Laboratory of Adjuvant and Antigen Research, Silver Spring, MD, United States, 2Catholic University of America, Department of Biology, Washington, DC, United States, 3U.S. Military HIV Research Program (MHRP), Walter Reed Army Institute of Research, Laboratory of Adjuvant and Antigen Research, Silver Spring, MD, United States Background: Although HIV-1 primarily infects T-cells through the interaction of viral envelope with CD4 and a co-receptor CCR5/CXCR4, CD4 expresses in low level in macrophages. Recently, sialic acid-binding Ig-like lectin 1 (Siglec-1, CD169), which is highly expressed on the cell surface of macrophages, has been identified as a major receptor for HIV-1 infection. It is known that Siglec-1 binds to glycans containing sialic acid. To further understand the mechanism; we determined the binding affinity/kinetics of monomeric gp120 and trimeric gp145 to assess if there were differences in their ability to bind to Siglec-1. We further narrowed down the env-binding motif to the V2 loop of gp120. Finally, we conducted an inhibition assay in the presence/absence of lactose (LA), 2, 6¢-Sialyllactose (6¢-SL) and sialic acid (SA) to identify the nature of the interactions. Methods: Siglec-1 was immobilized on a CM5 chip on a Biacore T200. JRFL and SF162 (clade B) gp120, gp145, and V2 loop proteins were captured. In additional experiments, these env proteins were immobilized, while Siglec-1 was injected over that surface. For the inhibition assays, LA, SL and SA were mixed with the env proteins or with Siglec-1 and then injected onto the immobilized Siglec-1 or env proteins, respectively.
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