S100B and infection: Infection of Jurkat cells with vesicular stomatitis virus G protein-pseudotyped HIV-1 lentiviral vector encoding green fluorescent protein (VSV-G-HIV-GFP) induces a decrease in PSGL-1 levels; therefore, different HIV proteins, i.e., p55 Gag, Vpr, Vif, Nef, and Vpu were analyzed to assess whether any one of these may be responsible for the downregulation of PSGL-1.