pdf file with full text is in the Library Host range and cellular tropism of the human exogenous gammaretrovirus XMRV. Kristin Stieler, Claudia Schulz, Madakasira Lavanya, Martin Aepfelbacher, Carol Stocking, Nicole Fischer Abstract Recently, the first human infection with an exogenous gammaretrovirus (XMRV) was reported. In its initial description, XMRV was confined to prostate stromal fibroblasts, although subsequent reports demonstrated XMRV protein expression in prostate epithelial cells. Most recently, XMRV has been detected in blood cells of patients with chronic fatigue syndrome. The aim of this study was to elucidate the transmission routes and tissue tropism of XMRV by comparing its host range, receptor usage and LTR functionality with other MLV isolates. We demonstrate using pseudotype experiments that XMRV Env mediates efficient infection of cells from different species. We show that replication competent XMRV infects various human cell types, including hematopoietic cell lines and prostate stromal fibroblasts. XMRVLTR activity is significantly higher in the prostate cancer cell line LNCaP and in prostate stromal fibroblasts, compared to other cell types tested and could be one factor contributing to efficient viral spread in prostate tissue.