When HIV enters the body, it heads first to the gut-associated lymphoid tissue – part of the digestive tract that harbours a high concentration of target immune cells. There, the virus attacks CD4 T cells – whose job it is to sound the alarm to other immune cells – and all but wipes them out before CD4 T-cell counts noticeably drop in the blood or lymph nodes. Now, researchers have used 3D electron microscopy to capture detailed footage of how the infection plays out in the guts of mice whose immune systems contain mostly human lymphoid cells. The video shows HIV particles, known as virions (blue), budding off from host cells and accumulating in pools between cells, biding their time before they infect other cells. This discovery raises the prospect of using antibodies to target these ‘free’ virions to fight the spread of HIV where it begins, in the gut.
Written by Daniel Cossins