Molecular characterization of Vibrio cholerae phage-type 6b epidemic isolates from 1998 to 2001 in Sichuan province / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the molecular characteristics of phage-type 6b isolates emerging in 1998-2001 cholera epidemics in Sichuan province.</p><p><b>METHODS</b>Isolates were analyzed by phage-typing, pulsed field gel electrophoresis (PFGE) and ompW gene sequencing.</p><p><b>RESULTS</b>All phage-type 1b and 6b isolates in Sichuan province from 1998 to 2001 were toxigenic. A total of 24 patterns were identified after PFGE analysis, and one predominant pattern consisted of 13 isolates. Several 1b and 6b isolates from Sichuan and isolates of the 1b from other provinces showed the same PFGE pattern. Mutation in ompW gene was found in 6b isolates.</p><p><b>CONCLUSION</b>V.cholerae O1 6b isolates in Sichuan province from 1998 to 2001 have special genetic markers, and might genetically correlate with contemporaneous 1b isolates.</p>

Sequence analysis of housekeeping genes recA, dnaE, and mdh in different serogroups or biotypes of Vibrio cholerae isolated from China / 南方医科大学学报

<p><b>OBJECTIVE</b>To analyze sequences of the housekeeping genes including recA, dnaE, and mdh in different serogroups or different biotypes of Vibrio cholerae (VC) strains isolated from China.</p><p><b>METHODS AND RESULTS</b>recA, dnaE, and mdh genes of Vibrio cholerae were obtained by PCR, sequenced and analyzed. Forty-four variable bases were identified in the 500 bases of recA gene of 18 VC strains, and the mutation of only 3 variable bases could result in changes of 2 amino acids. In the 600 bases of dnaE genes of 18 strains, 32 variable bases were found and only 1 contributed to an amino acid change. In the 367 bases of mdh genes of 18 strains, only 1 variable base was identified whose mutation involved an amino acid convertion. Toxic EI Tor biotype (EVC) strains and toxic O139 serogroup strains were closely related. Non-toxic strains of different serogroups or types were lowly related. Non-toxic and toxic strains of different serogroups or types were lowly related.</p><p><b>CONCLUSION</b>Toxic EVC and toxic O139 serogroup strains isolated from different areas of China may evolve from a common original strain, and toxic O139 VC strains may come from toxic EVC strains.</p>