Effects and mechanisms of monoclonal and polyclonal human antibodies in protection of humanized mice from HIV-1 challenge.

Recent clinical trials of both active and passive immunization demonstrate the barriers to the successful development of efficacious preventative HIV-1 vaccines and prophylactic antibody treatments. More facile means to explore these interventions in preclinical models could fill key gaps in knowledge and contribute to identifying and optimizing the most promising interventions. Here we report simple adaptations to standard virus challenge strategies in the humanized mouse model that support evaluation of antibody-mediated protection from infection with fewer high stakes design choices and demonstrate evaluation of protection afforded by polyclonal human serum IgG antibodies (pAbs) and monoclonal antibodies (mAbs) with variable pharmacokinetic (PK) and functional profiles. Using these adaptations, we observed that both neutralization and Fc-mediated effector functions contribute to the in vivo antiviral activity of broadly-neutralizing antibody VRC01, that confounding of results due to differences in mAb PK can be overcome, and most promisingly, that polyclonal human serum IgG that exhibits potent neutralizing and Fc-effector function can protect from infection. Collectively, this work demonstrates insights into antibody-mediated protection and methods that hold promise in supporting testing the protection from HIV-1 afforded by human pAb responses induced by vaccination.