RESUMO
In this study, we investigated the CD4 T-helper response induced by ALVAC-HIV(vCP205) +/- rgp160MN/LAI-2 using a series of 15 overlapping amino acid peptides spanning the entire gp160MN/LAI-2 antigen. CD4 Env-specific T-cell lines were established from three groups of HIV-1-negative HIV vaccine recipients: vCP205 + gp160MN/LAI-2, vCP205 only, and gp160MN/LAI-2 only. CD4 Env-specific T-cell lines established from individuals who received the prime-boost vCP205 + rgp160MN/LAI-2 generated strong and broad T-helper responses scattered across the Env sequence, whereas Env-specific T-cell lines from individuals receiving the vCP205 vaccine alone generated reactivity to only a few peptides. CD4 -specific T-cell lines were also established from HIV-1-infected individuals and demonstrated poor reactogenicity to Env peptides in both breadth and amplitude of response. These results highlight the complexity of major histocompatibility complex class II presentation and CD4 antigen-specific reactivity, emphasizing the need to better understand these crucial T-helper cell responses in the setting of HIV infection and HIV vaccine development.
Assuntos
Vacinas contra a AIDS/imunologia , Linfócitos T CD4-Positivos/imunologia , Epitopos de Linfócito T/imunologia , Antígenos HIV/imunologia , Proteína gp160 do Envelope de HIV/imunologia , Infecções por HIV/imunologia , Adulto , Sequência de Aminoácidos , Linfócitos T CD4-Positivos/citologia , Células Cultivadas , Mapeamento de Epitopos , Epitopos de Linfócito T/química , Antígenos HIV/química , Infecções por HIV/virologia , Humanos , Ativação Linfocitária , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/imunologia , VacinaçãoRESUMO
Structure-function analysis of the hepatitis C virus (HCV) envelope glycoproteins, E1 and E2, has been difficult due to the unavailability of HCV virions. Truncated soluble forms of E2 have been used as models to study virus interaction with the putative HCV receptor CD81, but they may not fully mimic E2 structures on the virion. Here, we compared the CD81-binding characteristics of truncated E2 (E2(660)) and full-length (FL) E1E2 complex expressed in mammalian cells, and of HCV virus-like particles (VLPs) generated in insect cells. All three glycoprotein forms interacted with human CD81 in an in vitro binding assay, allowing us to test a panel of well-characterized anti-E2 monoclonal antibodies (MAbs) for their ability to inhibit the glycoprotein-CD81 interaction. MAbs specific for E2 amino acid (aa) regions 396-407, 412-423 and 528-535 blocked binding to CD81 of all antigens tested. However, MAbs specific for regions 432-443, 436-443 and 436-447 inhibited the interaction of VLPs, but not of E2(660) or the FL E1E2 complex with CD81, indicating the existence of structural differences amongst the E2 forms. These findings underscore the need to carefully select an appropriate ligand for structure-function analysis.
