Contributions of the oligopeptide permeases in multistep of Vibrio alginolyticus pathogenesis

Abstract

Vibrio alginolyticus has been associated with several diseases of cultivated marine animals, and has led to considerable economic losses. The oligopeptide permease (Opp) has been proven to play a variety of important roles in nutrition and virulence in several bacteria. In our previous research, the opp gene cluster was identified in Vibrio alginolyticus with transcriptome sequence, which also indicated that the Opp system might play roles in the regulation of adhesion. In this study, the relationship between V. alginolyticus virulence and the opp gene cluster was determined using gene silencing followed by RT‐qPCR, in vitro adhesion assay, growth curves detection in the presence of glutathione (GSH) as a toxic substrate, hemolysis assay, biofilm assay, and artificial infection. Silencing these genes led to deficiencies in adhesion, peptide internalization, biofilm production, hemolytic activity, and virulence. The expression levels of hapr, hapa, tlh, and hlya, which are important genes closely related to the hemolytic activity of Vibrio, were significantly downregulated in all of the RNAi groups. Furthermore, the expression of oppA, oppB, oppC, oppD, and oppF was significantly influenced by temperature, starvation, and pH. These results indicate that (1) oppABCDF contributed in multistep of V. alginolyticus pathogenesis, including adhesion, biofilm production, and hemolytic activity; (2) oppABCDF was sensitive to different temperatures, changes in pH, and increased starvation time.

The role of rpoS in the regulation of Vibrio alginolyticus virulence and the response to diverse stresses

“…A QuantStudio™ 6 Flex real‐time PCR system (ABI, USA) was used to carry out qRT–PCR with SYBR green I (Dongsheng, China) as instructed by the manufacturer (Liu, Huang, et al., ). The expression level of rpoS was assessed, with 16S RNA expression used for normalization ( n = 6).…”

“…Reverse transcription was carried out with A Reverse Aid Mu-MLV cDNA synthesis kit (TransGen Biotech, China) from 2.0 mg total RNA, as instructed by the manufacturer (Zhang, Huang, Zhao, & Hu, 2017). instructed by the manufacturer (Liu, Huang, et al, 2017). The expression level of rpoS was assessed, with 16S RNA expression used for normalization (n = 6).…”

“…Haemolysis assays were carried out as described by Liu, Huang, et al, 2017 andLiu, Wang, et al, 2017. Rabbit blood (Ping Rui Biotechnology Co., Ltd. Beijing, China) was washed three times with PBS.…”

A metabolomic investigation into the temperature‐dependent virulence of Pseudomonas plecoglossicida from large yellow croaker (Pseudosciaena crocea)

“…Eighty healthy E. coioides were randomly divided into four groups. Each fish was intraperitoneally injected with 100 μl of wild‐type or stable silenced strains of P. plecoglossicida (1 × 10 7 cfu/ml) at 18°C (Liu et al, ), while sterile PBS was chosen as a negative control. Infected fish were observed daily until 10 days post‐injection.…”

The effect of a temperature-sensitive prophage on the evolution of virulence in an opportunistic bacterial pathogen

“…Manual curation of the genes associated with GATC motifs related to phenotypic changes showed that many of them were involved in (1) transcription regulation, (2) cell metabolism, (3) nutrient capture and transport into the cell, (4) excretion into the outer medium, (5) cell envelope structure (including peptidoglycan and lipopolysaccharide biosynthesis) and (6) biofilm formation, adherence or motility (Figure 5, gene functions panel and Supplementary Tables S5–S11). Many of those functional categories have been shown to be critical for pathogen virulence in other bacterial species, in particular for nutrient capture in the challenging host medium (Ren et al, 2018; Liu et al, 2017), for recognition of the host habitat via its nutrient signature (López-Garrido et al, 2015; Krypotou et al, 2019) and for biofilm formation, adherence and motility which have a key role in colonization and successful invasion of the host tissues (Turner et al, 2009; Luo et al, 2017). The numerous candidate genes involved in lipopolysaccharide biosynthesis also suggest that the O antigen, which can classically be involved both in cell recognition by phages and in bacterial virulence in its host (Chart et al, 1989; Li and Wang, 2012), could act as a major player of evolutionary trade-offs between bacterial virulence and resistance to phage infection.…”