Development and Application of Antibody Discovery Technologies in HIV-1 Infection and Multivalent Vaccination

Abstract

Human immunodeficiency virus (HIV) is a significant public health threat and the causative agent of acquired immunodeficiency syndrome (AIDS). Studying the antibody response in the context of HIV-1 infection and multivalent vaccination can identify factors that contribute to the elicitation of broadly neutralizing antibody responses. To this end, I carried out a vaccine study that evaluated the effect of the number of HIV-1 Env strains included in multivalent vaccinations. Guinea pigs were vaccinated with cocktails of two, three, or six diverse strains of HIV-1 Env, and the polyclonal antibody responses were evaluated for virus neutralization. I found that immunizing with more strains of HIV-1 Env is sometimes beneficial but may be detrimental when too many strains are used; immunizations with three strains outperformed immunizations with two or six strains. Next, I adapted the antibody discovery platform LIBRA-seq (Linking B cell receptor to antigen specificity through sequencing) to be compatible with guinea pig splenocytes. I carried out LIBRA-seq on two guinea pigs from our vaccine study, guinea pig 109 (gp109) and guinea pig 112 (gp112), isolating several tier 2 neutralizing antibodies. Sequence analysis of three antibodies, one from gp109 and two from gp112, revealed the existence of vaccine-elicited guinea pig public clonotypes. Additionally, I characterized a novel antibody lineage isolated from an HIV-1 infected donor that cross-reacts with diverse viral antigens including HIV-1 Env, influenza hemagglutinin (HA), and coronavirus spike. I found that at least one antibody in this lineage, antibody 2526, possess a mannose-binding pocket that confers cross-reactivity to diverse viral pathogens while showing no signs of autoreactivity. These experiments shed light on how cross-reactive antibody responses can be elicited at the polyclonal level through multivalent HIV-1 vaccination and delineate mechanisms of diverse antigen recognition at the monoclonal level.