Comparison between Env-specific T-cell epitopic responses in HIV-1-uninfected adults immunized with combination of ALVAC-HIV(vCP205) plus or minus rgp160MN/LAI-2 and HIV-1-infected adults

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.