P05-07. Evaluation of peripheral and bone marrow B cell responses in rhesus macaques after immunization with soluble HIV-1 gp140 trimers

Background Broadly neutralizing antibodies (bNAbs) against HIV-1 are not efficiently elicited by vaccination despite considerable efforts. bNAb elicitation is likely limited both by current envelope glycoproteins (Env) immunogens, which are not sufficient mimics of the native Env spike complex, and by the lack of immunization regimens that promote optimal development and maturation of B cell responses. So far, analyses from protein immunization studies focus mainly on serological antibody responses and less on responses at the B cell level. Here, we characterize frequencies of antigen-specific antibody secreting cells (ASC) and memory B cells in the periphery and bone marrow of rhesus macaques immunized with soluble gp140 trimers. These analyses provide a foundation for the design of improved immunization protocols to elicit bNAbs against HIV-1.