Toxin-coregulated pilus, but not mannose-sensitive hemagglutinin, is required for colonization by Vibrio cholerae O1 El Tor biotype and O139 strains.

The relative contributions of toxin-coregulated pilus (TCP) and cell-associated mannose-sensitive hemagglutinin (MSHA) to the colonization ability of Vibrio cholerae O1 El Tor biotype strains and O139 Bengal strains was determined by using isogenic parental and in-frame deletion mutant pairs in the infant mouse cholera model. Both the El Tor and O139 tcpA mutant strains showed a dramatic defect in colonization as indicated by their competitive indices, whereas deletion of mshA had a negligible effect on colonization in either background.