RELATIVE SIGNIFICANCE OF MANNOSE-SENSITIVE HEMAGGLUTININ AND TOXIN-COREGULATED PILL IN COLONIZATION OF INFANT MICE BY VIBRIO-CHOLERAE EL-TOR

A previously described in-frame deletion in mshA-the gene encoding the structural subunit of the mannose-sensitive hemagglutinin pilus-has b een introduced into the chromosome of three El Tor O1 strains of Vibri o cholerae. None of the Delta mshA mutants showed significant attenuat ion or loss of colonization potential in the infant mouse cholera mode l, A second mutation, created by insertion of a kanamycin resistance c artridge into Delta mshA, also failed to affect in vivo behavior, In c ontrast, strains carrying mutations in tcpA (encoding the monomer of t he toxin-coregulated pilus [TCP]) were markedly attenuated and showed dramatically impaired colonization. This result was in line with those of previous studies, Protection tests performed with antibodies to TC P and to MshA showed that only the former were able to confer immunity against El Tor O1 challenge in this model, Studies with mutants const ructed from two O139 strains similarly suggest that TCP but not mannos e-sensitive hemagglutinin pill are critical for colonization by strain s of this serogroup.