HIV-1 and IgA Antibodies: Interactions and implications

Antibodies, particularly Immunoglobulin A (IgA), play a crucial role in mucosal tissues as immune effectors against pathogens and as immunomodulators of the microbiota. During infection with human immunodeficiency virus type 1 (HIV-1), a systemic and mucosal IgA antibody response is triggered. Although naturally produced serum IgA specific to HIV-1 envelope protein are quantitatively and qualitatively lower than their IgG counterparts, they also possess antiviral properties such as neutralization and Fc-dependent effector functions. Neutralizing IgA antibodies can block mucosal transmission of HIV-1 in animal models, suggesting that their induction through vaccination could be pivotal for infection prevention. Recently, broadly neutralizing IgA antibodies have been identified in some individuals living with HIV-1. Given the potential for vaccination to induce these mucosally protective antibodies, research efforts are needed to better understand their development and functions. This review discusses the general roles of IgA antibodies in homeostasis and antimicrobial immunity, and explores their implications in antibody responses during HIV-1 infection.