Composition and immunochemical properties of outer membrane proteins of Vibrio cholerae

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Abstract
The protein compositions of the outer membranes of various M. cholerae strains, belonging to both biotypes (El Tor and classical) and both serotypes (Ogawa and Inaba), were analyzed by electrophoresis on polyacrylamide slab gels in the presence of sodium dodecyl sulfate. All these strains contained a major protein band of MW 48,000. They differed in the composition and proportions of minor proteins. The outer membrane protein profile was influenced by the growth medium. A protein band of MW 15,000 was observed in the outer membrane when V. cholerae Ogawa 395 (classical) was grown in peptone-water, whereas a protein MW 68,000 appeared when it was grown in the synthetic medium. Under anaerobic growth conditions the proportion of the MW 13,000 protein was greatly enhanced. The outer membrane contained heat-modifiable proteins, as the protein bands with MW 41,000 and 37,000 disappeared when membrane proteins were disaggregated in sodium dodecyl sulfate at or above 60.degree. C. The antisera to the outer membrane proteins of V. cholera Ogawa 395 (classical) produced immunoprecipitation to the outer membrane proteins of both biotypes and both serotypes. The antisera agglutinated bacteria of both biotypes and both serotypes, suggesting the presence of a common protein antigen in the outer membrane of V. cholerae.