Expression of the C-type lectin receptor CD205 on B cells mediates HIV-1 binding and trans infection of CD4+ T cells

Antigen presenting cells (APC) can bind HIV-1 and subsequently trans infect CD4+ T cells. In comparison to direct (cis) infection of CD4+ T cells by free virus, APC-mediated HIV-1 trans infection is significantly more efficient and requires lower virus titers. As such, B cell-mediated HIV-1 trans infection of CD4+ T cells, particularly in secondary lymphoid organs (SLO) where B and CD4+ T cells interact frequently in and around B cell follicles, represents an efficient pathway for establishing and maintaining the latent HIV-1 reservoir. The molecular events involved in HIV-1 binding to B cells and transfer to CD4+ T cells are poorly understood. B cells are exposed to various activation signals in SLO including CD40 ligand (CD40L), interleukin-4 (IL-4), interferon-g (IFN-g), and B cell activating factor (BAFF). Here, we treated B cells with these different signals, or combination of signals, to identify those that facilitate HIV-1 binding to B cells and trans-infection of CD4+ T cells, and the mechanisms involved. We found that CD40L/IL-4 stimulated B cells are highly efficient mediators of HIV-1 trans infection of CD4+ T cells due to their enhanced capacity to bind HIV-1. Single cell RNA sequencing of differentially stimulated B cell populations revealed that CD40L/IL-4 stimulation significantly induced expression of the C-type lectin CD205. Confocal microscopy revealed that HIV-1 and CD205 co-localized on CD40L/IL-4 stimulated B cells, and antibody blocking of CD205 on these cells significantly reduced HIV-1 binding. Taken together, this study identifies CD205 as a critical receptor on B cells that facilitates HIV-1 binding and the transfer of virus to CD4+ T cells. Insight into the role of B cell mediated HIV-1 trans infection of CD4+ T cells is critical to optimizing the effectiveness of HIV-1 therapies in SLO.