Enhancing effects of adjuvanted 2009 pandemic H1N1 influenza A vaccine on memory B-cell responses in HIV-infected individuals.

Abstract

To assess the humoral immune response to low-dose AS03-adjuvanted and standard-dose nonadjuvanted 2009 pandemic H1N1 influenza A vaccine in HIV-infected aviremic individuals receiving antiretroviral therapy and in uninfected individuals. A three-arm study. Two clinics: one at the National Institutes of Health in Bethesda, Maryland, USA; and the other at the Maple Leaf Medical Clinic in Toronto, Ontario, Canada. HIV-infected and HIV-uninfected adults. Single intramuscular 15 μg dose of the monovalent inactivated 2009 pandemic H1N1 influenza A vaccine without adjuvant or 3.75 μg dose of the same strain with adjuvant AS03. Immunogenicity, as measured by hemagglutination inhibition (HAI) antibody titers and vaccine-specific memory B-cell responses. A total of 74 participants were enrolled. Twenty-one HIV-infected individuals received the low-dose adjuvanted 2009 pandemic H1N1 influenza A vaccine. Twenty-nine HIV-infected and 24 HIV-uninfected individuals received the standard-dose nonadjuvanted vaccine. There were no significant differences in antibody responses at 9 weeks postvaccination among the three groups studied. However, the IgG memory B-cell response against the vaccine was significantly higher in the HIV-infected group that received the low-dose adjuvanted vaccine when compared to the HIV-infected and uninfected groups that received the standard-dose nonadjuvanted vaccine. Conclusions remained unchanged after regression adjustment for age, gender, CD4 T-cell count, and baseline HAI titer. These data suggest that adjuvants could be used to expand coverage through dose sparing and improve humoral immune responses in immunocompromised individuals.