Open AccessGenetic Traits of Vibrio cholerae O1 Haitian Isolates That Are Absent in Contemporary Strains from Kolkata, India
Author(s) -
Priyanka Ghosh,
Arindam Naha,
Gururaja Perumal Pazhani,
T. Ramamurthy,
Asish K. Mukhopadhyay
Publication year - 2014
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0112973
Subject(s) - el tor , vibrio cholerae , biology , cholera , cholera toxin , dna gyrase , strain (injury) , genetics , microbiology and biotechnology , gene , insertion sequence , genome , escherichia coli , transposable element , bacteria , anatomy
The world's worst cholera epidemic in Haiti (2010) coerced to trace the origin and dissemination of the causative agent Vibrio cholerae O1 for proper management of cholera. Sequence analysis of the Haitian strain showed several variations in the genes encoding cholera toxin B subunit ( ctxB ); toxin-co-regulated pilus ( tcpA ), repeat in toxins ( rtxA ), quinolone resistance-determining region (QRDR) of gyrase A ( gyrA ), rstB of RS element along with the change in the number of repeat sequences at the promoter region of ctxAB . Our earlier studies showed that variant tcpA ( tcpA CIRS ) and ctxB ( ctxB7 ) first appeared in Kolkata during 2003 and 2006, respectively. The present study revealed that a variant rtxA was first isolated in Kolkata during 2004 and probably formed the genetic background for the emergence of the ctxB 7 allele as we were unable to detect a single strain with the combination of El Tor rtxA and ctxB 7. The variant gyrA was first time detected in Kolkata during 1994. The Kolkata strains contained four heptad repeats (TTTTGAT) in their CT promoter regions whereas Haitian strains carried 5 heptad repeats. Haitian strains had 3 nucleotide deletions at the rstB gene, which is a unique feature of the classical biotype strains. But the Kolkata strains did not have such deletion mutations in the rstB . Our study demonstrated the existence of some Haitian genetic traits in Kolkata isolates along with the dissimilarities in genomic content with respect to rstB and ctxAB promoter region. Finally, we conclude that Haitian variant strain may be evolved due to sequential event in the Indian subcontinent strain with some cryptic modification in the genome.