Induction of strong HIV-1-specific CD4+ T-cell responses using an HIV-1 gp120/NefTat vaccine adjuvanted with AS02A in antiretroviral-treated HIV-1-infected individuals.

Background: Induction of HIV-1-specific CD4(+) T-cell responses by therapeutic vaccination represents an attractive intervention to potentially increase immune control of HIV-1. Methods: We performed a double-blinded, randomized, placebo-controlled clinical trial to determine the safety and immunogenicity of GlaxoSmithKline Biologicals' HIV-1 gp120/NefTat subunit protein vaccine formulated with the AS02(A) Adjuvant System in subjects with well-controlled chronic HIV-1 infection on highly active antiretroviral therapy. Ten individuals received the vaccine; whereas adjuvant alone or placebo was given to 5 subjects each. Immunogenicity was monitored by intracellular cytokine flow cytometry and carboxyfluorescein succinimidyl ester-based proliferation assays. Results: The vaccine was well tolerated with no related serious adverse events. Vaccine recipients had significantly stronger gp120-specific CD4(+) T-cell responses which persisted until week 48 and greater gp120-specific CD4(+) T-cell proliferation activity as compared with controls. In the vaccine group, the number of participants who demonstrated positive responses for both gp120-specific CD4(+) T-cell interleukin-2 production and gp120-specific CD8(+) T-cell proliferation were significantly higher at week 6. Conclusions: The gp120/NefTat/AS02(A) vaccine induced strong gp120-specific CD4(+) T-cell responses and a higher number of vaccinees developed both HIV-1-specific CD4(+) T-cell responses and CD8(+) T-cell proliferation. The induction of these responses may be important in enhancing immune-mediated viral control.