Commensal bacteria in the human microbiota can contribute to the production of antibodies that cross-react with the spike protein of SARS-CoV-2, potentially providing a level of immunity against the virus.
- Commensal bacteria in the human microbiota can induce cross-reactive IgA antibodies against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. - Some specific commensal bacteria, like Streptococcus salivarius, can stimulate the production of cross-reactive anti-RBD antibodies. - Severely ill COVID-19 patients have reduced levels of Streptococcus and Veillonella bacteria and decreased levels of anti-RBD IgA antibodies at mucosal surfaces. - The findings suggest that certain microbial species in the human microbiota can contribute to the immune response against SARS-CoV-2.
This is from biorxiv in 2021 at Link.
Keywords: cross-reactive antibody responses, RBD domain, spike protein, SARS-CoV-2, commensal microbiota
Abstract
The commensal microflora is a source for multiple antigens that may induce cross-reactive antibodies against host proteins and pathogens. However, whether commensal bacteria can induce cross-reactive antibodies against SARS-CoV-2 remains unknown. Here we report that several commensal bacteria contribute to the generation of cross-reactive IgA antibodies against the receptor-binding domain (RBD) of the SARS-CoV-2 Spike protein. We identified SARS-CoV-2 unexposed individuals with RBD-binding IgA antibodies at their mucosal surfaces. Conversely, neutralising monoclonal anti-RBD antibodies recognised distinct commensal bacterial species. Some of these bacteria, such as Streptococcus salivarius, induced a cross-reactive anti-RBD antibodies upon supplementation in mice. Conversely, severely ill COVID-19 patients showed reduction of Streptococcus and Veillonella in their oropharynx and feces and a reduction of anti-RBD IgA at mucosal surfaces. Altogether, distinct microbial species of the human microbiota can induce secretory IgA antibodies cross-reactive for the RBD of SARS-CoV-2.
Competing Interest Statement
J.N., L. B., and A.K. have a pending patent application with regard to utilization of commensal bacteria for induction of antiviral immune responses.
Paper in collection COVID-19 SARS-CoV-2 preprints from medRxiv and bioRxiv