Notably, HIV-1 lacking Nef is infection defective, and the infectivity of Nef-deficient virions could be complemented by drugs disrupting the cortical actin cytoskeleton [161] or by pseudotyping virions with the vesicular stomatitis virus glycoprotein (VSV-G), which fuses viral particles in low pH endocytic vesicles. This evidence concerns the gene S100B and infection.