UC San Diego

Cholera causes severe diarrheal illness in young children, but the mechanisms underlying age-dependent susceptibility remain unclear. Experimental cholera in neonatal mice recapitulates age-dependent susceptibility: suckling mice are susceptible to Vibrio cholerae colonization and cholera toxin (CT)-dependent disease, whereas adult mice are not readily colonized and do not develop cholera-like disease. Here, we define a developmental window in which susceptibility declines sharply over the first two postnatal weeks.To determine whether the gut microbiota contributes to this developmental transition, we first tested whether short-term microbiota manipulation could alter susceptibility to V. cholerae. Microbiota from both neonatal and adult donors protected adult germ-free mice from V. cholerae colonization, but adult microbiota transplants did not readily alter the neonatal gut microbiota or confer resistance to susceptible neonatal mice. In contrast, transplantation of intestinal contents from 14-day-old donors reduced disease severity and neonatal recipients, and sterile filtered 14-day-old small intestinal contents reduced both V. cholerae colonization and disease. These findings suggest that developmental microbiota-associated factors can rapidly influence susceptibility independently of stable donor microbiota engraftment.We next investigated how early life disruption of microbiota assembly affects the developmental emergence of resistance. Maternal antibiotic exposure disrupted vertical transmission of maternal microbiota to offspring and altered distal small intestinal microbiota assembly, extending the window of susceptibility to CT-dependent V. cholerae colonization and disease. Pups born to antibiotic-treated dams exhibited reduced Lactobacillaceae and increased Enterobacteriaceae, and reintroduction of an endogenous Lactobacillus isolate restored offspring lactobacilli levels and reestablished resistance to experimental cholera at two weeks of age. Consistent with a direct protective role, increasing lactobacilli in susceptible neonatal mice reduced experimental cholera burden, and cultures of the endogenous Lactobacillus isolate as well as spent culture media acidified the in vitro growth environment and rapidly eliminated recoverable V. cholerae. Together, these findings support a model in which the emergence of resistance to experimental cholera during early life is associated with maturation of the gut microbiota and acquisition of specific microbiota-associated protective functions. These findings also identify vertical transmission of maternal microbiota to offspring and lactobacilli-associated antagonism as determinants of early-life resistance to cholera.