Within the first few hours of an HIV-1 infection, the virus enters both Langerhans cells (purple) and CD4+ T lymphocytes (not shown) residing in the vaginal epithelium. This TEM shows a Langerhans cell (purple) exiting an isolated epithelium to disseminate the HIV-1. A long cytoplasmic extension of the Langerhans cell remains anchored between basal keratinocytes and contains a large vacuole with one HIV-1BaL virion (red) inside. Viruses taken up by Langerhans cells are usually degraded in endosomal compartments to generate antigens for presenting to T cells. However, HIV may have a mechanism to slow down its degradation in intracellular compartments of dendritic cells, allowing the virion to survive and infect other cells of the immune system.
By Florian Hladik, Polachai Sakchalathorn, and Juliana M. McElrath, University of Washington