Background & Objectives : Several studies have been conducted to explore anti-HIV drugs. Discovery and study of novel anti-HIV-1 compounds need live viruses and has serious biosafety concerns. In this research we reported a novel and safe system for assaying the cytopathic effects of HIV by using single cycle replicable (SCR) HIV-1 virions.

  Methods: To produce the SCR HIV-1 virions, pMD2G, pmzNL4-3 and pSPAX2 plasmids were co-transfected into HEK293T cells. Different amount of SCR virions were used to infect target cells (MT-2). Within the infected cells, the number of formed syncytia was counted under the light microscopy. The lethal effects of the SCR HIV virions were measured using XTT proliferation assay.

  Results: Formation of syncytia among SCR HIV infected cells was detectable 24 hours after infection. Highest amount of syncytia was seen 72 hours after infection. Increase in the amount of virions caused increasing of syncytia and the cytopathic effects of SCR HIV-1. Infection with more than 1600ng P24 SCR HIV decreased the syncytium formation and viability of all cells. The calculated IC50 (50 percent inhibitory capacity) for nevirapine and BMS806 using this method was 50nM and 30nM, respectively.

  Conclusion: SCR HIV-1 virions are replicable only for one cycle. Using these virions can improve the safety of HIV researches. Herein, we optimized the assaying of HIV induced cytopathic effects by using SCR HIV-1 (NL4-3) virions. The accuracy of this method was accepted by quantifying the anti-HIV-1 effects of nevirapine and BMS806 by (SCR) HIV-1 virions.