VIBRIO-CHOLERAE HEMAGGLUTININ PROTEASE INACTIVATES CTX-PHI/

Pathogenic strains of Vibrio cholerae are lysogens of the filamentous phage CTX phi, which carries the genes for cholera toxin (ctxAB), We f ound that the titers of infective CTX phi in culture supernatants of E l Tor CTX phi lysogens increased rapidly during exponential growth but dropped to undetectable levels late in stationary-phase growth. When CTX phi transducing particles were mixed with stationary-phase culture supernatants of El Tor strains, CTX phi infectivity was destroyed, Ou r data indicate that this growth phase-regulated factor, designated CD F (CTX phi-destroying factor), is the secreted hemagglutinin/protease (HA/P) of V, cholerae, A strain containing a disrupted hap gene, which encodes HA/P of V; cholerae, did not produce CDF activity in culture supernatants, Introduction of the HA/P-expressing plasmid pCH2 restore d CDF activity. Also, CDF activity in culture supernatants of a variet y of pathogenic V. cholerae isolates varied widely but correlated with the levels of secreted HA/P, as measured by immunoblotting with anti- HA/P antibody. CDF was purified from V. cholerae culture supernatants and shown to contain a 45-kDa poly-peptide which bound anti-HA/P antib odies and which comigrated with HA/P in sodium dodecyl sulfate-polyacr ylamide gel electrophoresis, The production of high levels of secreted HA/P by certain V. cholerae strains may be a factor in preventing CTX phi reinfection in natural environments and in the human host.