Prevention of contamination by xenotropic murine leukemia virus-related virus: susceptibility to alcohol-based disinfectants and environmental stability.

Xenotropic murine leukemia virus-related virus (XMRV) represents a novel γ-retrovirus that is capable of infecting human cells and has been classified as a biosafety level 2 (BSL-2) organism. Hence, XMRV represents a potential risk for personnel in laboratories worldwide. Here, we measured the stability of XMRV and its susceptibility to alcohol-based disinfectants. To this end, we exposed an infectious XMRV reporter virus encoding a secretable luciferase to different temperatures, pH values, and disinfectants and infected XMRV-permissive Raji B cells to measure residual viral infectivity. We found that 1 min treatment of XMRV particles at 60°C is sufficient to reduce infectivity by 99.9%. XMRV infectivity was maximal at a neutral pH but was reduced by 86% at pH 4 and 99.9% at pH 10. The common hand and surface disinfectants ethanol and isopropanol as well as the cell fixation reagent paraformaldehyde abrogated XMRV infectivity entirely, as indicated by a reduction of infectivity exceeding 99.99%. Our findings provide evidence of specific means to inactivate XMRV. Their application will help to prevent unintended XMRV contamination of cell cultures in laboratories and minimize the risk for laboratory personnel and health care workers to become infected with this biosafety level 2 organism.

Cholesterol depletion inactivates XMRV and leads to viral envelope protein release from virions: evidence for role of cholesterol in XMRV infection.

Membrane cholesterol plays an important role in replication of HIV-1 and other retroviruses. Here, we report that the gammaretrovirus XMRV requires cholesterol and lipid rafts for infection and replication. We demonstrate that treatment of XMRV with a low concentration (10 mM) of 2-hydroxypropyl-ß-cyclodextrin (2OHpßCD) partially depleted virion-associated cholesterol resulting in complete inactivation of the virus. This effect could not be reversed by adding cholesterol back to treated virions. Further analysis revealed that following cholesterol depletion, virus-associated Env protein was significantly reduced while the virions remained intact and retained core proteins. Increasing concentrations of 2OHpßCD (≥20 mM) resulted in loss of the majority of virion-associated cholesterol, causing disruption of membrane integrity and loss of internal Gag proteins and viral RNA. Depletion of cholesterol from XMRV-infected cells significantly reduced virus release, suggesting that cholesterol and intact lipid rafts are required for the budding process of XMRV. These results suggest that unlike glycoproteins of other retroviruses, the association of XMRV glycoprotein with virions is highly dependent on cholesterol and lipid rafts.