Identification and whole-genome sequencing analysis of Vibrio vulnificus strains causing pearl gentian grouper disease in China

Abstract

Vibrio vulnificus is a pathogenic bacterium that causes disease in marine fish, affecting fish farming and human health worldwide. In May 2021, in the Bohai Bay region, a disease broke out in commercially farmed pearl gentian grouper (♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatus), causing huge economic losses. The diseased fish had skin lesions, water accumulation in their abdomens, and showed tissue and organ damage. V. vulnificus biotype 2 has been reported in eels and other marine fish, but it is less reported in pearl gentian grouper. In this study, the pathogenic strain isolated from diseased fish was identified as V. vulnificus EPL 0201 biotype 2 on the basis of physiological and biochemical characteristics and the results of 16S rRNA gene and gyrB sequencing, virulence gene detection, and recursive infection experiments. To gain a comprehensive understanding of the pathogenicity and drug resistance of this strain, whole-genome sequencing was performed. Whole-genome analysis showed that the gene map of this strain was complete. The Virulence Factor Database annotation results showed that this strain had the key virulence factor genes vvhA and rtxA, which cause host disease. In addition, this strain had genes conferring resistance against cephalosporins, aminoglycosides, tetracyclines, and sulfonamides. Antimicrobial susceptibility testing confirmed the presence of these resistance genes identified in the genome. The results of this study show that V. vulnificus EPL 0201 biotype 2 is a multi-drug resistant strain with high pathogenicity.

Vibrio parahaemolyticus and Vibrio vulnificus in vitro colonization on plastics influenced by temperature and strain variability

“…This is especially apparent as the vv155 strain has a 16S rRNA designated type B genotype, which has a strong association with clinical strains, meaning that it may have a high level of virulence in humans ( Nilsson et al, 2003 ). While type A strains are more environmentally associated, infections in humans from type A have still been reported, and been shown to be more virulent in mice (LD 50 = 10 5 –10 6 CFU) when compared to type B strains (LD 50 = 10 8 CFU; Amaro, 1992 ; Amaro and Biosca, 1996 ; Nilsson et al, 2003 ; Drake et al, 2007 ; Jones and Oliver, 2009 ; Çam et al, 2019 ; Wu et al, 2022 ). Only the V. vulnificus ATCC33147 type B strain CFUs on LDPE and PS had above the considered threshold LD 50 dose of 10 5 –10 6 CFUs (without adjusting the CFUs per mm 2 of surface type) needed to be lethal in animals at all temperatures tested ( Amaro and Biosca, 1996 ; Jeong and Satchell, 2012 ; Marx et al, 2013 ).…”

Rapid visual nucleic acid detection of Vibrio alginolyticus by recombinase polymerase amplification combined with CRISPR/Cas13a

“…The gyrB gene is variable yet conserved, as its genetic code can undergo nucleotide substitutions without changing the translation results of the amino acid sequence. Therefore, this gene has certain value in the identi cation of Vibrio species (Wu et al 2022). Therefore, in this study, we designed and screened speci c primers for the gyrB gene of V. alginolyticus.…”

“…Due to the similarity of the coding sequences for virulence genes among Vibrio species, the 16S rRNA gene is commonly used as a target for nucleic acid detection. However, the highly conserved nature of the 16S rRNA gene limits the accuracy of identi cation between closely related species(Liu et al 2021;Wu et al 2022). In recent years,…”