Deciphering the possible role of < i > ctxB7 < /i > allele on higher production of cholera toxin by Haitian variant < i > Vibrio cholerae < /i > O1

by Arindam Naha, Rahul Shubhra Mandal, Prosenjit Samanta, Rudra Narayan Saha, Sreeja Shaw, Amit Ghosh, Nabendu Sekhar Chatterjee, Pujarini Dutta, Keinosuke Okamoto, Shanta Dutta, Asish Kumar Mukhopadhyay Cholera continues to be an important public health concern in developing countries where proper hygiene and sanitation are compromised. This severe diarrheal disease is caused by the Gram-negative pathogenVibrio cholerae belonging to serogroups O1 and O139. Cholera toxin (CT) is the prime virulence factor and is directly responsible for the disease manifestation. ThectxB gene encodes cholera toxin B subunit (CTB) whereas the A subunit (CTA) is the product ofctxA gene. Enzymatic action of CT depends on binding of B pentamers to the lipid-based receptor ganglioside GM1. In recent years, emergence ofV.cholerae Haitian variant strains withctxB7 allele and their rapid spread throughout the globe has been linked to various cholera outbreaks in Africa and Asia. These strains produce classical type (WT) CTB except for an additional mutation in the signal sequence region where an asparagine (N) residue replaces a histidine (H) at the 20th amino acid position (H20N) of CTB precursor (pre-CTB). Here we report that Haitian variantV.cholerae O1 strains isolated in Kolkata produced higher amount of CT compared to contemporary O1 El Tor variant strains underin vitro virulence inducing conditions. We observed that thectxB7 allele, itself plays a pivotal role in higher CT production. Based o...
Source: PLoS Neglected Tropical Diseases - Category: Tropical Medicine Authors: Source Type: research