First published February 20, 2018 - More info
The discovery of an HIV-1 cure remains a medical challenge because the virus rebounds quickly after the cessation of combination antiretroviral drug therapy (cART). Here, we investigate the potential of an engineered tandem bi-specific broadly neutralizing antibody (bs-bnAb) as an innovative product for HIV-1 prophylactic and therapeutic interventions. We discovered that by preserving two scFv binding domains of each parental bnAb, a single-gene-encoded tandem bs-bnAb, namely BiIA-SG, displayed significantly improved breadth and potency. BiIA-SG neutralized all 124 HIV-1 pseudotyped viruses tested, including global subtypes/recombinant forms, transmitted/founder viruses, and variants less or not susceptible to parental and many bnAbs, with an average IC50 value of 0.073 µ/ml (range < 0.001 to 1.03 µg/ml). In humanized mice, an injection of BiIA-SG conferred sterile protection when administered prior to challenges with diverse live HIV-1 stains. Moreover, while BiIA-SG delayed viral rebound in a short-term therapeutic setting when combined with cART, a single injection of AAV-transferred BiIA-SG gene resulted dose-dependently in prolonged in vivo expression of BiIA-SG, which was associated with complete viremia control and subsequent elimination of infected cells in humanized mice. These results warrant the clinical development of BiIA-SG as a promising bs-bnAb-based biomedical intervention for prevention and treatment of HIV-1 infections.