Regulatory role of VvsB protein on serine protease activity of VvsA in Vibrio vulnificus.

Background: Vibrio vulnificus NCIMB2137, a Gram-negative, metalloprotease negative estuarine strain was isolated from a diseased eel. A 45 kDa chymotrypsin-like alkaline serine protease known as VvsA has been recently reported as one of the major virulence factor responsible for the pathogenesis of this strain. The vvsA gene along with a downstream gene vvsB, whose function is still unknown constitute an operon designated as vvsAB.

Effect of physicochemical and microbiological factors on the development of viable but non-culturable and resuscitation states of Vibrio cholerae.

Background: Vibrio cholerae can endure harsh environmental conditions by transitioning into viable but non-culturable (VBNC) form and resuscitate upon return of appropriate conditions.

Method: In this study, we assessed the impact of physicochemical and microbiological factors, on the development of low temperature-induced VBNC state and subsequent recovery by temperature upshift.

Results: In estuarine water, Vibrio cholerae exhibits a slower decline in culturability over a period of 77 days as compared to 10 days in fresh water.

Structural and functional characterization of colonization factors AIBI-CS6 and AIIBII-CS6 of enterotoxigenic Escherichia coli.

Over time, the structure and function of the broadly dispersed colonization factor (CF) CS6 of enterotoxigenic Escherichia coli (ETEC) have become more significant. CS6 is composed of tightly-associated subunits, CssA and CssB which due to presence of natural point mutation gave rise to CS6 subtypes. In contrast to the other ETEC CFs, CS6 is an afimbrial, spherical-shaped oligomers of (CssA-CssB) complex where 'n' is concentration dependent.

Investigation of the Expression of Serine Protease in Vibrio vulnificus.

Vibrio vulnificus is a Gram-negative estuarine bacterium that causes infection in immuno-compromised patients, eels, and shrimp. V. vulnificus NCIMB2137, a metalloprotease-negative strain isolated from a diseased eel, produces a 45-kDa chymotrypsin-like alkaline serine protease known as VvsA.

Regulators of natural competence in Vibrio parahaemolyticus.

Vibrio parahaemolyticus can degrade insoluble chitin with the help of chitinase enzymes that generate soluble N-acetyl glucosamine oligosaccharides (GlcNAc) to induce a state of natural competence for the uptake of extracellular DNA. In this study, we had evaluated the role of various regulatory factors such as TfoX, CytR, OpaR, and RpoS during natural transformation of V. parahaemolyticus.

Chitin degradation and its effect on natural transformation: a systematic genetic study in .

The degradation of polymeric chitin by chitinase liberates soluble N-acetyl glucosamine oligosaccharides (GlcNAc), a source of nutrition that can also induce a state of natural genetic competence in . This analysis revealed that among seven predicted chitinases, the synergistic action of VPA0055 (ChiA2), VP0619 (ChiB), and VPA0832 (Cdx) were essential for the robust growth and high transformation frequency on chitin. The endochitinase, ChiA2, and periplasmic chitinase, Cdx were indispensable for chitin degradation.

Cholera Outbreaks in India, 2011-2020: A Systematic Review.

Fecal contamination of water sources and open defecation have been linked to cholera outbreaks in India. However, a systematic review on the drivers responsible for these outbreaks has yet to be published. Here, we systematically review the published literature on cholera outbreaks in India between 2011 and 2020.

The Impact of Protease during Recovery from Viable but Non-Culturable (VBNC) State in .

can survive cold stress by entering into a viable but non-culturable (VBNC) state, and resuscitation can be induced either by temperature upshift only or the addition of an anti-dormancy stimulant such as resuscitation-promoting factors (Rpfs) at suitable temperature. In this study, the role of proteinase K was analyzed as an Rpf in . A VBNC state was induced in AN59 in artificial seawater (ASW) media at 4 °C, and recovery could be achieved in filtered VBNC microcosm, called spent ASW media, merely by a temperature upshift to 37 °C.

Cholera Rapid Diagnostic Tests for the Detection of O1: An Updated Meta-Analysis.

Unlabelled: The rapid diagnosis of cholera contributes to adequate outbreak management. This meta-analysis assesses the diagnostic accuracy of cholera rapid tests (RDTs) to detect O1.

Methods: Systematic review and meta-analysis.

Accuracy of cholera rapid diagnostic tests: a systematic review and meta-analysis.

Background: Cholera is an acute diarrheal disease caused by Vibrio cholerae O1 or O139. Cholera rapid diagnostic tests (RDTs) are widely used to screen for cholera cases. However, their accuracy has not been systematically reviewed.

Regulation of Chitin-Dependent Growth and Natural Competence in .

Vibrios can degrade chitin surfaces to soluble N-acetyl glucosamine oligosaccharides (GlcNAc) that can be utilized as a carbon source and also induce a state of natural genetic competence. In this study, we characterized chitin-dependent growth and natural competence in and its regulation. We found that growth on chitin was regulated through chitin sensors ChiS (sensor histidine kinase) and TfoS (transmembrane transcriptional regulator) by predominantly controlling the expression of chitinase VPA0055 (ChiA2) in a TfoX-dependent manner.

Comparative proteomic analysis to characterize temperature-induced viable but non-culturable and resuscitation states in Vibrio cholerae.

Vibrio cholerae can survive environmental adversities by entering into a viable but non-culturable (VBNC) state and is able to resuscitate under favourable conditions. In this study, an environmental strain of V. cholerae (AN59) showed a decrease in culturability from 4×10 to ≤ 3 c.

Functional analysis of N-terminal propeptide in the precursor of Vibrio vulnificus metalloprotease by using cell-free translational system.

Vibrio vulnificus is a human pathogen causing fatal septicemia with edematous and hemorrhagic skin damage. Among multiple virulence factors, an extracellular metalloprotease termed as V. vulnificus protease (VVP) is known to play a crucial role in eliciting the skin damage.

Role of a sensor histidine kinase ChiS of Vibrio cholerae in pathogenesis.

Vibrio cholera survival in an aquatic environment depends on chitin utilization pathway that requires two factors, chitin binding protein and chitinases. The chitinases and the chitin utilization pathway are regulated by a two-component sensor histidine kinase ChiS in V. cholerae.

Functional Role of N- and C-Terminal Amino Acids in the Structural Subunits of Colonization Factor CS6 Expressed by Enterotoxigenic Escherichia coli.

Unlabelled: CS6 is a common colonization factor expressed by enterotoxigenic Escherichia coli It is a two-subunit protein consisting of CssA and CssB in an equal stoichiometry, assembled via the chaperone-usher pathway into an afimbrial, oligomeric assembly on the bacterial cell surface. A recent structural study has predicted the involvement of the N- and C-terminal regions of the CS6 subunits in its assembly. Here, we identified the functionally important residues in the N- and C-terminal regions of the CssA and CssB subunits during CS6 assembly by alanine scanning mutagenesis.

Characterization of oligomeric assembly of colonization factor CS6 from enterotoxigenic Escherichia coli.

The widely distributed colonization factor (CF) CS6 of enterotoxigenic Escherichia coli (ETEC) has gained importance over the years in terms of its structure and function. CS6 is an afimbrial assembly in contrast to the other ETEC CFs, which are mostly fimbrial. A recent study predicted a linear fibre model for recombinant chimeric CS6 and formation of oligomers in solution.

Two specific amino acid variations in colonization factor CS6 subtypes of enterotoxigenic Escherichia coli results in differential binding and pathogenicity.

CS6 is the predominant colonization factor of enterotoxigenic Escherichia coli (ETEC). We report the existence of multiple CS6 subtypes caused by natural point mutations in cssA and cssB, the structural genes for CS6. The subtype AIBI was mostly associated with ETEC isolated from diarrhoeal cases, whereas AIIBII was mostly found in asymptomatic controls.

Real-time PCR-based mismatch amplification mutation assay for specific detection of CS6-expressing allelic variants of enterotoxigenic Escherichia coli and its application in assessing diarrheal cases and asymptomatic controls.

Enterotoxigenic Escherichia coli (ETEC) expressing the colonization factor CS6 is widespread in many developing countries, including India. The different allelic variants of CS6, caused by point mutations in its structural genes, cssA and cssB, are designated AIBI, AIIBII, AIIIBI, AIBII, and AIIIBII. A simple, reliable, and specific mismatch amplification mutation assay based on real-time quantitative PCR (MAMA-qPCR) was developed for the first time for the detection of CS6-expressing ETEC, along with the identification of allelic variations.