Microevolution of <i>Vibrio parahaemolyticus</i> Isolated from Clinical, Acute Hepatopancreatic Necrosis Disease Infecting Shrimps, and Aquatic Production in China

Abstract

Vibrio parahaemolyticus is the leading cause of bacteria-associated foodborne diarrheal diseases and specifically causes early mortality syndrome (EMS), which is technically known as acute hepatopancreatic necrosis disease (AHPND), a serious threat to shrimp aquaculture. To investigate the genetic and evolutionary relationships of V. parahaemolyticus in China, 184 isolates from clinical samples (VPC, n=40), AHPND-infected shrimp (VPE, n=10), and various aquatic production sources (VPF, n=134) were collected and evaluated by a multilocus sequence analysis (MLST). Furthermore, the presence of potential virulence factors (tlh, tdh, and trh) and single nucleotide polymorphisms (SNPs) in V. parahaemolyticus isolates was assessed using genomic sequencing. Analyses of virulence factors revealed that the majority of VPC isolates (97.5%) possessed the tdh and/or trh genes, while most of the VPF isolates (83.58%) did not encode hemolysin genes. Therefore, we hypothesized that the environment is a potential reservoir that promotes horizontal DNA transfer, which drives evolutionary change that, in turn, leads to the emergence of novel, potentially pathogenic strains. Phylogenetic analyses identified VPF-112 as a non-pathogenic maternal strain isolated from aquatic products and showed that it had a relatively high evolutionary status. All VPE strains and some VPC strains were grouped into several small subgroups and evenly distributed on phylogenetic trees. Anthropogenic activities and environmental selective pressure may be important factors influencing the process of transforming strains from non-pathogenic to pathogenic bacteria.

Characterization of Carbapenem-Resistant Enterobacteriaceae Cultured From Retail Meat Products, Patients, and Porcine Excrement in China

“…CC10 was the largest clonal complex, including 14 strains and 5 STs (ST10, ST48, ST167, ST617, and ST7122), which meant these strains are the main source of infection in the area we studied, carrying a high risk of transmission. Horizontal transmission of plasmids occurs more readily between strains within a clonal complex than between strains from different clonal complexes ( Lu et al, 2020 ). A wide variety of carbapenem-resistant encoding genes were identified, including bla NDM–1 , bla NDM–5 , bla NDM–7 , and bla NDM–9 .…”

“…Annotation for each isolate and tree embellishment were visualized using iTOL 6 . The Global Optimal eBURST (goeBURST) full MST algorithm was used to compare against the PubMLST database, to highlight the potential relationships of different strain isolates and sequence types (STs) ( Lu et al, 2020 ). The genetic information and evolutionary characteristics of all strains were considered.…”

“…The genetic information and evolutionary characteristics of all strains were considered. Nucleotide sequence analyses of 16S rRNA genes of all strains were conducted with MEGA ( Lu et al, 2020 ). Virulence determinants were investigated by aligning the reads to the Virulence Factor Database (VFDB) 7 , 8 .…”

Coordination of primary metabolism and virulence factors expression mediates the virulence of Vibrio parahaemolyticus towards cultured shrimp ( Penaeus vannamei )

“…2019; Lu et al . 2020). Nevertheless, these studies do not demonstrate how these virulence‐related genes contribute to the virulence level.…”