The Release of HIV-1 is not Impacted by Levels of Tetherin in Human Hela Cell Lineage

Abstract

Tetherin is an interferon-induced transmembrane protein that maintains enveloped viruses tethered to cell membranes. Several viruses have developed proteins capable to counteract tetherin from their respective hosts, e.g. accessory protein Vpu from Human Immunodeficiency Virus (HIV-1) and Nef from some Simian Imunodeficiency Viruses (SIVs). Studies involving the role of tetherin in the release of viruses were done in the context of tetherin superexpression. The real impact of tetherin in a physiological condition is still a matter of debate. Therefore, our group started to investigate the differences in levels of tetherin and in the release of HIV-1 and SIVcpz in HeLa cells, a cell line that constitutively express tetherin. HeLa cells were transfected with HIV-1 WT, HIV-1 ΔNef and HIV-1 ΔVpu infectious clones and after 48 hours, cell lysates were collected and submitted to SDS-PAGE to assess tetherin levels and the levels of released viruses were analyzed by ELISA αp24. As expected, we observed about 25% reduction on levels of tetherin from both HIV-1 WT and HIV-1ΔNef when compared with HIV-1 ΔVpu. However, the levels of released virus were not altered despite of the down-modulation of tetherin. Our results show that endogenous levels of human tetherin are not detrimental for release of HIV-1.