Broad Neutralizing Antibodies to HIV Env and Other Complex Viral Antigens from Vaccinated Cows

Abstract

The idea of using antibodies to restrain HIV viral replication has been a growing interest since many years ago. HIV-patient serum with elite virus-neutralizing breadth has led to preparation of broadly neutralizing antibodies (BrNAbs) with long and highly mutated CDRH3 domains that can neutralize a broad array of viral strains and prevent transmission in animal models. Recent advances have resulted in the discovery of BrNAbs that are more potent and can neutralize many HIV-1 subtypes. However, elicitation of these antibodies in infected individuals usually requires a long time of antigen exposure. Though, BrNAbs are shown to be successful either therapeutically or prophylactically against HIV-1, production of these antibodies in bulk, commercial-sized batches is expensive and non-affordable particularly for poor countries. Therefore, more durable preventative or therapeutic strategies are required. Immunization of the cows with HIV Env is shown to be capable of producing 20 kg purified anti-HIV-1 BrNAbs and this amount could be sufficient for 2 million × 10 mg doses for formulation and pre-clinical testing as an HIV microbicide. In addition, bovine immunoglobulins typically have variable third heavy complementarity determining regions (CDRH3) that may potentially facilitate access to antigenic epitopes that are very difficult for other species to engage. Thus, cows could be engaged to elicit anti-HIV antibodies with the features of human BrNAbs and bovine colostrum could be a promising and cheap resource for development of combination microbicides.