Isolation and complete genome sequence analysis of Vibrio rotiferianus strain TO-01 from Trachinotus ovatus to reveal its pathogenicity and drug resistance

Abstract

Vibrio rotiferianus is a pathogenic bacterium that is widely distributed in the ocean and can cause diseases in a variety of marine animals, including fish, shrimp and shellfish. In this study, we isolated and identified V. rotiferianus strain TO-01 from diseased Trachinotus ovatus. Infected fish exhibited a range of pathological symptoms, including lethargy in swimming, blackened body coloration, skin ulceration and erratic side swimming. Tissue section examination revealed pronounced damage to the liver, spleen and gills of the infected fish. An analysis of immune factor expression revealed a significant increase in the expression of inflammatory factors, including interleukin (IL)-1, IL-2, IL-6 receptor and IL-21, in the spleen and kidney of fish infected with TO-01 at 6 h post-infection. To gain a more in-depth comprehension of the pathogenicity and drug resistance of V. rotiferianus, we conducted whole genome sequencing. The total genome length of V. rotiferianus was 4734,075 bp, and 74 virulence factors were predicted within the genome. Most of these virulence genes were associated with bacterial adhesion and flagellar motility. A gene associated with group sensing, cqsA, and a gene associated with hemolysin, tlh, were also identified. The prediction of drug resistance genes was in agreement with the results of drug sensitivity assays, both of which indicated that TO-01 has significant resistance to β-lactams. The findings of this study significantly enhance our understanding of the pathogenic mechanism of V. rotiferianus and give crucial insights into disease prevention and control in the management of T. ovatus.