Construction and characterization of recombinant Vibrio cholerae strains carrying heterologous genes encoding non-01 antigen or cholera enterotoxin.

In an attempt to study the effect of heterologous genes on the virulence of Vibrio cholerae 01 and non-01, rfb genes encoding biosynthesis of non-01 antigens were introduced by homologous recombination into the chromosome of V. cholerae 01 strain 569B (serotype Inaba, biotype classical). Recombinant strains were obtained which were not agglutinated with the diagnostic cholera 01 antiserum and were not sensitive to the cholera diagnostic bacteriophage, but produced as much cholera toxin as 569B and were highly virulent in the infant rabbit intraintestinal injection model. These data indicate that the rfb genes from the studied V. cholerae non-01 did not alter the virulence phenotype of V. cholerae 01. In contrast, cloned ctxAB genes from V. cholerae 01 encoding cholera toxin introduced into a non-pathogenic strain lead to efficient secretion of cholera toxin but to only low virulence in the infant rabbit model.