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Delineating virulence of Vibrio campbellii: a predominant luminescent bacterial pathogen in Indian shrimp hatcheries

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Title Delineating virulence of Vibrio campbellii: a predominant luminescent bacterial pathogen in Indian shrimp hatcheries
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Creator S. Kumar
C. B. Kumar
V. Rajendran
N. Abishaw
P. S. Shyne Anand
S. Kannapan
V. K. Nagaleekar
K. K. Vijayan
S. V. Alavandi
 
Subject Vibrio campbellii
virulence
shrimp hatcheries
Litopenaeus vannamei
 
Description Luminescent vibriosis is a major bacterial disease in shrimp hatcheries and causes up to 100%
mortality in larval stages of penaeid shrimps. We investigated the virulence factors and genetic
identity of 29 luminescent Vibrio isolates from Indian shrimp hatcheries and farms, which were earlier
presumed as Vibrio harveyi. Haemolysin gene-based species-specific multiplex PCR and phylogenetic
analysis of rpoD and toxR identified all the isolates as V. campbellii. The gene-specific PCR revealed
the presence of virulence markers involved in quorum sensing (luxM, luxS, cqsA), motility (flaA,
lafA), toxin (hly, chiA, serine protease, metalloprotease), and virulence regulators (toxR, luxR) in
all the isolates. The deduced amino acid sequence analysis of virulence regulator ToxR suggested
four variants, namely A123Q150 (AQ; 18.9%), P123Q150 (PQ; 54.1%), A123P150 (AP; 21.6%), and
P123P150 (PP; 5.4% isolates) based on amino acid at 123rd (proline or alanine) and 150th (glutamine
or proline) positions. A significantly higher level of the quorum-sensing signal, autoinducer-2 (AI-2,
p = 2.2e−12), and significantly reduced protease activity (p = 1.6e−07) were recorded in AP variant,
whereas an inverse trend was noticed in the Q150 variants AQ and PQ. The pathogenicity study in
Penaeus (Litopenaeus) vannamei juveniles revealed that all the isolates of AQ were highly pathogenic
with Cox proportional hazard ratio 15.1 to 32.4 compared to P150 variants; PP (5.4 to 6.3) or AP (7.3
to 14). The correlation matrix suggested that protease, a metalloprotease, was positively correlated
with pathogenicity (p > 0.05) and negatively correlated (p < 0.05) with AI-2 and AI-1. The syntenic
organization of toxS-toxR-htpG operon in V. campbellii was found to be similar to pathogenic V.
cholerae suggesting a similar regulatory role. The present study emphasizes that V. campbellii is a
predominant pathogen in Indian shrimp hatcheries, and ToxR plays a significant role as a virulence
regulator in the quorum sensing—protease pathway. Further, the study suggests that the presence of
glutamine at 150th position (Q150) in ToxR is crucial for the pathogenicity of V. campbellii.
 
Date 2024-05-02T17:14:57Z
2024-05-02T17:14:57Z
2021-08-04
 
Type Research Paper
 
Identifier Kumar, S., Kumar, C.B., Rajendran, V. et al. Delineating virulence of Vibrio campbellii: a predominant luminescent bacterial pathogen in Indian shrimp hatcheries. Sci Rep 11, 15831 (2021). https://doi.org/10.1038/s41598-021-94961-4
2045-2322
https://www.nature.com/articles/s41598-021-94961-4
http://krishi.icar.gov.in/jspui/handle/123456789/82580
 
Language English
 
Relation 15831;
 
Publisher Nature Portfolio