In vitro Study on Synergistic Interactions Between Free and Encapsulated Q-Griffithsin and Antiretrovirals Against HIV-1 Infection.

Introduction Human immunodeficiency virus (HIV) remains a persistent global challenge, impacting 38 million people worldwide. Antiretrovirals (ARVs) including tenofovir (TFV), raltegravir (RAL), and dapivirine (DAP) have been developed to prevent and treat HIV-1 via different mechanisms of action. In parallel, a promising biological candidate, griffithsin (GRFT), has demonstrated outstanding preclinical safety and potency against HIV-1. While ARV co-administration has been shown to enhance virus inhibition, synergistic interactions between ARVs and the oxidation-resistant variant of GRFT (Q-GRFT) have not yet been explored. Here, we co-administered Q-GRFT with TFV, RAL, and DAP, in free and encapsulated forms, to identify unique protein-drug synergies. Methods Nanoparticles (NPs) were synthesized using a single or double-emulsion technique and release from each formulation was assessed in simulated vaginal fluid. Next, each ARV, in free and encapsulated forms, was co-administered with Q-GRFT or Q-GRFT NPs to evaluate the impact of co-administration in HIV-1 pseudovirus assays, and the combination indices were calculated to identify synergistic interactions. Using the most synergistic formulations, we investigated the effect of agent incorporation in NP-fiber composites on release properties. Finally, NP safety was assessed in vitro using MTT assay. Results All active agents were encapsulated in NPs with desirable encapsulation efficiency (15–100%), providing ~20% release over 2 weeks. The co-administration of free Q-GRFT with each free ARV resulted in strong synergistic interactions, relative to each agent alone. Similarly, Q-GRFT NP and ARV NP co-administration resulted in synergy across all formulations, with the most potent interactions between encapsulated Q-GRFT and DAP. Furthermore, the incorporation of Q-GRFT and DAP in NP-fiber composites resulted in burst release of DAP and Q-GRFT with a second phase of Q-GRFT release. Finally, all NP formulations exhibited safety in vitro. Conclusions This work suggests that Q-GRFT and ARV co-administration in free or encapsulated forms may improve efficacy in achieving prophylaxis.