• anti-HIV microbicide candidate;
  • binding;
  • entry inhibitor of HIV;
  • griffithsin;
  • virucide

Abstract Background  The predominant mode of HIV-1 transmission is by heterosexual contact. The cervical/vaginal mucosa is the main port of HIV entry in women. A safe and effective topical microbicide against HIV is urgently needed to prevent sexual transmission. Hence, we evaluated griffithsin (GRFT), a 12.7 kDa carbohydrate-binding protein, both native and recombinant GRFT, potently inhibited both CXCR4-and CCR5-tropic HIV infection and transmission in vitro.

Methods  The antiviral efficacy of native and recombinant GRFT against CXCR4-and CCR5-tropic HIV and SHIV strains and SIVmac251 was evaluated by in vitro assays. We also evaluated the time course of antiviral activity and stability of GRFT in cervical/vaginal lavage as a function of pH 4–8.

Results  Griffithsin blocked CXCR4-and CCR5-tropic viruses at less than 1 nm concentrations and exhibited a high potency. GRFT was stable in cervical/vaginal lavage fluid and maintained a similar potency of anti-HIV activity. GRFT is not only a highly potent HIV entry inhibitor, but also prevents cell fusion and cell-to-cell transmission of HIV.

Conclusions  The in vitro efficacy of GRFT revealed low cytotoxicity, high potency, rapid onset of antiviral activity and long-term stability in cervical/vaginal lavage. GRFT is an excellent candidate for anti-HIV microbicide development.