S100B and viral infectious disease: Together, these results suggest that enrichment for latent infection in the non-dividing cell subpopulation cannot be attributed to the inhibitory effect of Vpr on cell cycle progression, but rather is more likely due to increased overall expression of HIV accessory proteins during productive wild type virus infection, especially those linked to apoptotic induced cell death (i.e. Vpr, Tat, Nef) [43].