Genetic relatedness of selected clinical Vibrio cholerae O139 isolates from the southern coastal area of China over a 20-year period

Abstract

Vibrio cholerae O139 emerged as a causative agent of epidemic cholera in 1992 in India and Bangladesh, and was subsequently reported in China in 1993. The genetic relatedness and molecular characteristics of V. cholerae O139 in Guangdong Province, located in the southern coastal area of China, remains undetermined. In this study, we investigated 136 clinical V. cholerae O139 isolates from 1993 to 2013 in Guangdong. By conventional PCR, 123 (90·4%) isolates were positive for ctxB, ace and zot. Sequencing of the positive amplicons indicated 113 (91·7%) isolates possessed the El Tor allele of ctxB (genotype 3); seven carried the classical ctxB type (genotype 1) and three harboured a novel ctxB type (genotype 5). With respect to tcpA, 123 (90·4%) isolates were positive for the El Tor allele. In addition, pulsed-field gel electrophoresis (with NotI digestion) differentiated the isolates into clusters A and B. Cluster A contained seven of the non-toxigenic isolates from 1998 to 2000; another six non-toxigenic isolates (from 1998 and 2007) and all of the toxigenic isolates formed cluster B. Our results suggest that over a 20-year period, the predominant O139 clinical isolates have maintained a relatively tight clonal structure, although some genetic variance and shift has occurred. Our data highlight the persistence of toxigenic V. cholerae O139 in clinical settings in the southern coastal area of China.

Genomic diversities of ctxB, tcpA and rstR alleles of Vibrio cholerae O139 strains isolated from Odisha, India

“…The difference in pulsotypes of 2017 V. cholerae O139 isolates in comparison to other years might be due to the new variant of El Tor ctx B of V. cholerae O139 isolates (Pal et al ., 2019). Earlier studies demonstrated the genomic diversities of V. cholerae O139 isolates from Delhi, India (2001–2006) and also from Guangdon, China (1993–2013) that clearly showed the relatively high clonal expansions within the V. cholerae O139 isolates (Ghosh et al ., 2016; Li et al ., 2016). The present findings on PFGE analyses clearly evident that the genomes of V. cholerae O139 has undergone several adaptations and evolution since its first emergence in 1992 and spread to Odisha from 1999 to 2017.…”

“…Later on the genotypic changes in cholera toxin were reported from Delhi that showed majority of V. cholerae O139 strains harboured CT genotype 1 and 3 with a new clone of genotype 4 ( rst R Calc ) (Ghosh et al ., 2016). Similar findings from Guangdong, China also revealed the presence of a novel genotype 5 of V. cholerae O139 serogroup rather than genotype 1 and 3 during 1993–2013 (Li et al ., 2016). However, a new genotype of V. cholerae O139 carrying mutation in the prototype El Tor ctx B gene was reported during cholera outbreak in 2017 from Odisha (Pal et al ., 2019).…”

A Rough Variant of Nontoxigenic Vibrio Cholerae O139 Imported From Vietnam

“…The O139 Bengal was the result of a mutation, substituting the 22kb rfb region in O1 with a 35kb region of DNA encoding the surface polysacharide. (22). An altered variant named O139 Calcutta was later reported from an outbreak in 1996 (25)(26).…”

Genomic Epidemiology of Vibrio cholerae O139, Zhejiang Province, China, 1994–2018

“…cholerae O139 spread to China and was reported in Xinjiang Uygur Autonomous Region (6) and Guangdong Province (7) in 1993 and in Jiangxi Province and the cities of Beijing and Shanghai in 1994 (8). Most studies on O139 in China have focused on virulence and resistance-gene profiles, cholera toxin (CTX) types (7,8), and plasmid carriage (9). The genomic epidemiology of O139 in China and the phylogenetic relationship of isolates from China to isolates from other countries in Asia are still unknown.…”