Griffithsin (GRFT) is a potent HIV entry inhibitor (EC50 = 1.6 ng/ml in vitro). We have demonstrated that the GRFT/carrageenan (CG) combination provides synergistic antiviral activity against herpes simplex virus (HSV) and inhibits human papillomavirus (HPV).
The pharmacokinetics (PK) and antiviral efficacy of GRFT/CG fast dissolving inserts (FDIs) were examined in mice (PK and efficacy against HSV-2 and HPV) and rhesus macaques (RMs, for PK and efficacy against SHIV). Mouse-sized (0.1 mg GRFT, 0.3 mg CG) and RM-sized (1 mg GRFT, 3 mg CG) FDIs were inserted vaginally in depot medroxyprogesterone acetate (DMPA)-treated animals. In PK studies, vaginal fluid (VF, from mice and RMs) and plasma (from RMs) were collected at baseline and different time-points following FDI insertion. GRFT was quantified by ELISA. For efficacy testing, the same formulations in addition to placebo controls (hydroxyethyl cellulose or CG only) were evaluated in highly stringent vaginal models (SHIV-SF162P3 in RMs, HSV-2 and HPV16 PsV in mice). Formulations were applied vaginally 4 hours before virus challenge in each model. Statistical significance was assessed by Fisher’s exact test (SHIV and HSV-2) and Mann Whitney U test (HPV).
The GRFT/CG FDIs significantly protected RMs against SHIV-SF162P3 infection: 8/10 uninfected RMs in the GRFT/CG group vs. 0/10 uninfected in the CG group, 80% protection, p=0.0003 vs. CG. Similarly, the GRFT/CG FDIs protected mice (6 mice per formulation) against HSV-2 (60-73% uninfected in the GRFT/CG FDI group, p <0.0052 vs. placebo) and HPV PsV (100% uninfected in the GRFT/CG FDI group, p<0.0001 vs. placebo). GRFT was not detected in RM plasma. GRFT concentrations above 2 μg/mL (270x the EC90) were found in both mouse and RM VF 4 hours after FDI insertion.
GRFT/CG FDIs showed potent and broad spectrum in vivo activity against three incurable viral pathogens. The FDIs significantly protected RMs from SHIV-SF162P3 and mice from HSV-2 and HPV16 PsV infections, showing excellent safety profiles at 4 hours post dosing. These data support the further preclinical and clinical development of GRFT/CG FDIs.