S100B and infection: The addition of the ART drugs zidovudine (AZT; reverse transcriptase inhibitor) and nelfinavir (NFV; protease inhibitor) did not antagonize the FITC (Nef) shift observed postinfection with SIV in EV-positive cells relative to EV-negative cells (Fig. 8I to M), demonstrating that the Nef signal did not originate from new infections.