In Nature Microbiology, a team from Johns Hopkins University School of Medicine and the National Institute of Allergy and Infectious Diseases search for latent HIV reservoirs in individuals on long-term treatment. Using targeted sequencing and an experimental HIV detection assay known as the monocyte-derived macrophage quantitative viral outgrowth assay (MDM-QVOA), the investigators assessed blood samples collected between 2018 and 2022 from 10 men with HIV, focusing on individuals on long-term HIV suppressive antiretroviral treatment. Their search pointed to the presence of HIV genetic material in monocyte white blood cells and the macrophages derived from them, albeit at lower levels than those found in CD4-positive T cells — results they confirmed in samples from eight of the men and 22 women with HIV treated with antiretrovirals, where they found HIV reservoirs in monocyte cells from more than half of individuals. "The virus produced in the MDM-QVOA was capable of infecting bystander cells resulting in viral spread," they write. "These findings provide further evidence that myeloid cells meet the definition of a clinically relevant HIV reservoir and emphasize that myeloid reservoirs should be included in efforts towards an HIV cure."