Analyses of functional antibody responses in HIV-1-infected individuals after vaccination with rgp160

Abstract Background: The immune response to HIV infection has been extensively studied and the antibody response against the virus has been characterized in detail. It is, however, still unclear which immune function it is most important to stimulate when administering a vaccine against HIV. Objectives: To analyze the functional antibody responses in asymptomatic HIV-1-infected individuals after vaccination with rgp160. Study design: Forty-nine asymptomatic HIV-1-infected individuals were followed for 9 months and analyzed for changes in functional antibody responses. Forty of them received HIV-1 envelope rgp160 injections and nine did not. Results: Increased levels of antibodies mediating neutralization and cellular cytotoxicity (ADCC) could be seen in subjects who also showed a better CD4 development compared with the patients without increased levels of functional antibodies. Out of nine matched HIV-infected and influenza-immunized controls, none had increased neutralizing activity and only one had an increased ADCC titer. An increased capacity to block soluble CD4 binding to gp120 occurred in 10 immunized patients. Seroreactivity and avidity maturation were detectable to peptides representing consensus HIV-1 envelope regions, indicating an anamnestic response to the patients own virus. Conclusions: The humoral immune response in HIV-1-infected individuals was moderately influenced by repeated gp160 immunizations, while previous studies have shown that HIV-specific T-cell reactivity was strongly increased.