Brains are composed of different cell types and the image from microscopy shows what cells EcoHIV infects in a mixture of mouse brain cells in tissue culture. The colors label specific elements in the cell mixture: blue shows DNA found in all cells, red shows a specific protein CD11b that is found in microglia, the brain cell related to macrophages found in other tissues, and green shows a marker inserted in EcoHIV to make it easier to see. The only areas with green are also colored red that together make bright orange. This means that the only cells infected by green EcoHIV are red, that is microglia. The cells that are not stained by red, either brain neurons or astrocytes, are not EcoHIV infected. This image thus demonstrates that EcoHIV infects mouse brain microglial cells, a process that we believe is responsible for induction of cognitive impairment by EcoHIV in mice. The image was obtained by Dr. Boe-Hyun Kim in Volsky lab, The Icahn School of Medicine at Mount Sinai, New York.