Physiologic Protective Antibodies to Gut Commensals in Humans

Brigida Rusconi of Washington University in the U.S. will determine whether female infants develop long-lived antibodies against gut bacteria that subsequently both protect against bacterial infections and promote healthy gut immune and microbiota development in their offspring. Enteric bacterial infections are leading causes of infant morbidity in low- and middle-income countries. Using their mouse model, they found that mothers lacking IgG antibodies, which normally develop before weaning, are unable to provide passive protection against enteric infections to their pups. They will adapt their microbial flow cytometry to test whether maternal serum IgGs react more strongly to infant gut bacteria, suggesting establishment in infancy, and whether they provide passive immunity during pregnancy. They will also analyze plasma from two-year-old infants to identify those with weak IgG reactivity and potential causes. Finally, using a malnutrition cohort in Pakistan, they will train local bioinformaticians and assess whether malnutrition inhibits anti-gut commensal IgG responses.