AUTHOR=Schaller Torsten , Bauby Hélène , Hué Stéphane , Malim Michael H. , Goujon Caroline TITLE=New insights into an X-traordinary viral protein JOURNAL=Frontiers in Microbiology VOLUME=Volume 5 - 2014 YEAR=2014 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2014.00126 DOI=10.3389/fmicb.2014.00126 ISSN=1664-302X ABSTRACT=Vpx is a protein encoded by members of the HIV-2/SIVsmm and SIVrcm/SIVmnd-2 lineages of primate lentiviruses, and which is packaged into viral particles. Vpx plays a critical role during the early steps of the viral life cycle and has been shown to counteract the SAMHD1 restriction factor in myeloid and resting T cells. However, it is becoming evident that Vpx is a multifunctional protein in that SAMHD1 antagonism is not its sole role. This review summarises the current knowledge on this X-traordinary protein.