Abstract
Cross-reactive epitopes (CREs) are similar epitopes on viruses that are recognized or neutralized by same antibodies. The S protein of SARS-CoV-2, similar to type I fusion proteins of viruses such as HIV-1 envelope (Env) and influenza hemagglutinin, is heavily glycosylated. Viral Env glycans, though host derived, are distinctly processed and thereby recognized or accommodated during antibody responses. In recent years, highly potent and/or broadly neutralizing human monoclonal antibodies (bnAbs) that are generated in chronic HIV-1 infections have been defined. These bnAbs exhibit atypical features such as extensive somatic hypermutations, long complementary determining region (CDR) lengths, tyrosine sulfation and presence of insertions/deletions, enabling them to effectively neutralize diverse HIV-1 viruses despite extensive variations within the core epitopes they recognize. As some of the HIV-1 bnAbs have evolved to recognize the dense viral glycans and cross-reactive epitopes (CREs), we assessed if these bnAbs cross-react with SARS-CoV-2. Several HIV-1 bnAbs showed cross-reactivity with SARS-CoV-2 while one HIV-1 CD4 binding site bnAb, N6, neutralized SARS-CoV-2. Furthermore, neutralizing plasma antibodies of chronically HIV-1 infected children showed cross neutralizing activity against SARS-CoV-2 pseudoviruses. Collectively, our observations suggest that human monoclonal antibodies tolerating extensive epitope variability can be leveraged to neutralize pathogens with related antigenic profile.
Highlights
Neutralizing antibodies targeting the HIV-1 envelope glycoprotein (Env) can neutralize a broad range of circulating HIV-1 isolates and have been called super-antibodies due to their remarkable potency and neutralization breadth against viruses with significant alterations in the core epitope [1]
The HIV-1 broadly neutralizing human monoclonal antibodies (bnAbs) were categorized into five categories based on their epitopes on the HIV-1 viral Env (Fig 1A)
CR3022, and CC12.1 were used as positive control while two antibodies targeting the envelope glycoprotein of simian immunodeficiency virus (SIV) were used as negative control
Summary
Neutralizing antibodies (bnAbs) targeting the HIV-1 envelope glycoprotein (Env) can neutralize a broad range of circulating HIV-1 isolates and have been called super-antibodies due to their remarkable potency and neutralization breadth against viruses with significant alterations in the core epitope [1]. V2-apex bnAbs have been shown to exhibit cross-group neutralization activity with viruses derived from HIV-1 group M, N, O and P Envs. They even show crossneutralization of simian immunodeficiency virus (SIV) isolates [4]. Though such extensive cross-neutralization potential of several bnAbs is often associated with poly and/or autoreactivity. Several glycan-dependent HIV-1 bnAbs, such as PGT121 and PGT151, have been shown to bind uninfected/bystander cells
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