Special Issue "Vibrio parahaemolyticus Extracellular Toxins: Potential Virulence Factors and Its Role in Disease"

A special issue of Toxins (ISSN 2072-6651). This special issue belongs to the section "Bacterial Toxins".

Deadline for manuscript submissions: 31 December 2021.

Special Issue Editors

Prof. Dr. Peter Bossier
E-Mail Website
Guest Editor
Laboratory of Aquaculture & Artemia Reference Center, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium
Interests: aquaculture; health management; microbial management
Dr. Vikash Kumar
E-Mail Website
Guest Editor
1. Laboratory of Aquaculture & Artemia Reference Center, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium
2. Aquatic Environmental Biotechnology and Nanotechnology (AEBN) Division, ICAR-Central Inland Fisheries Research Institute (CIFRI), Barrackpore 700120, India
Interests: aquaculture; shrimp immunology and microbiology; disease diagnosis; fish and shellfish health management

Special Issue Information

Dear Colleagues,

Vibrio parahaemolyticus is an important microbial pathogen, and several strains are capable of causing vibriosis, resulting in significant mortality and economic losses in animal production. V. parahaemolyticus is a heterogenous, Gram-negative, non-spore-forming and comma-shaped bacterium with a polar flagellum or several flagella. This pathogen is part of the autochthonous microflora of estuarine and coastal environments, as well as fish, bivalves and crustaceans in tropical-to-temperate zones all over the world. Apart from being found in fish and shellfish species (including shrimp and molluscs), this bacterium has been isolated from water, sediments, plankton, and marine mammals. The level of V. parahaemolyticus in the environment and various fish and shellfish species may vary depending on environmental and geographical factors. Interestingly, the production of extracellular virulence products by V. parahaemolyticus has been identified as one of the important factors for its pathogenesis. In addition, various exo-enzymes—such as lipase, phospholipase, caseinase, elastase, and hemolysin—determine the virulence of V. parahaemolyticus strains and have been found to be responsible for host mortality.

Apart from “classical” vibriosis, V. parahaemolyticus also cause acute hepatopancreatic necrosis disease (AHPND), originally known as early mortality syndrome (EMS), with a devastating impact on the shrimp aquaculture industry. V. parahaemolyticus becomes a virulent AHPND-causing strain by acquiring a pVA1 plasmid (63–70 kb) encoding the binary toxin PirAVp/PirBVp, homologous to the Photorhabdus luminescens insect-related (Pir) toxins PirA/PirB. The secreted binary PirAVp and PirBVp toxins are the primary virulence factor of AHPND-causing bacteria mediating AHPND and mortality in shrimp. Although the PirAVp and PirBVp toxins are directly responsible for shrimp mortality during AHPND, several other pathogenic extracellular proteins (ECPs) have been identified in V. parahaemolyticus strains—hemin; enterobactin; vibrioferrin; type I, II, and VI secretion system proteins; chemotaxis protein (60 kDa); flagellin (40 kDa); metalloproteases (PrtV protein, 62 kDa; VppC protein, 90 kDa; and VPM protein, 90 kDa); and serine proteases (VPP1, 43 kDa; VpSP37, 37 kDa; and PrtA, 71 kda)—that might contribute to the toxicity of AHPND-causing bacteria. Hence, deciphering the roles of virulence factors will help to improve our understanding of the V. parahaemolyticus infection process in host animals.

In this Special Issue, we cordially invite scientists from across the world to contribute their cutting-edge research on V. parahaemolyticus and its virulence factors responsible for the pathogenesis of the bacterium. Original research articles and short communications advancing the knowledge on virulence factors and how they interact with one another, either synergistically or antagonistically, and influence the toxicity of V. parahaemolyticus in the host are welcome. We also invite scientists to write reviews for this Special Issue.

Prof. Dr. Peter Bossier
Dr. Vikash Kumar
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a double-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Toxins is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Vibrio parahaemolyticus
  • vibriosis
  • virulence factors
  • exo-enzymes
  • PirAVP/PirBVP toxins
  • AHPND

Published Papers (2 papers)

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Research

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Article
A Novel Glutathione S-Transferase Gtt2 Class (VpGSTT2) Is Found in the Genome of the AHPND/EMS Vibrio parahaemolyticus Shrimp Pathogen
Toxins 2021, 13(9), 664; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13090664 - 17 Sep 2021
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Abstract
Glutathione S-transferases are a family of detoxifying enzymes that catalyze the conjugation of reduced glutathione (GSH) with different xenobiotic compounds using either Ser, Tyr, or Cys as a primary catalytic residue. We identified a novel GST in the genome of the shrimp pathogen [...] Read more.
Glutathione S-transferases are a family of detoxifying enzymes that catalyze the conjugation of reduced glutathione (GSH) with different xenobiotic compounds using either Ser, Tyr, or Cys as a primary catalytic residue. We identified a novel GST in the genome of the shrimp pathogen V. parahaemolyticus FIM- S1708+, a bacterial strain associated with Acute Hepatopancreatic Necrosis Disease (AHPND)/Early Mortality Syndrome (EMS) in cultured shrimp. This new GST class was named Gtt2. It has an atypical catalytic mechanism in which a water molecule instead of Ser, Tyr, or Cys activates the sulfhydryl group of GSH. The biochemical properties of Gtt2 from Vibrio parahaemolyticus (VpGSTT2) were characterized using kinetic and crystallographic methods. Recombinant VpGSTT2 was enzymatically active using GSH and CDNB as substrates, with a specific activity of 5.7 units/mg. Low affinity for substrates was demonstrated using both Michaelis–Menten kinetics and isothermal titration calorimetry. The crystal structure showed a canonical two-domain structure comprising a glutathione binding G-domain and a hydrophobic ligand H domain. A water molecule was hydrogen-bonded to residues Thr9 and Ser 11, as reported for the yeast Gtt2, suggesting a primary role in the reaction. Molecular docking showed that GSH could bind at the G-site in the vicinity of Ser11. G-site mutationsT9A and S11A were analyzed. S11A retained 30% activity, while T9A/S11A showed no detectable activity. VpGSTT2 was the first bacterial Gtt2 characterized, in which residues Ser11 and Thr9 coordinated a water molecule as part of a catalytic mechanism that was characteristic of yeast GTT2. The GTT2 family has been shown to provide protection against metal toxicity; in some cases, excess heavy metals appear in shrimp ponds presenting AHPND/EMS. Further studies may address whether GTT2 in V. parahaemolyticus pathogenic strains may provide a competitive advantage as a novel detoxification mechanism. Full article
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Review

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Review
Acute Hepatopancreatic Necrosis Disease (AHPND): Virulence, Pathogenesis and Mitigation Strategies in Shrimp Aquaculture
Toxins 2021, 13(8), 524; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13080524 - 27 Jul 2021
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Abstract
Shrimp, as a high-protein animal food commodity, are one of the fastest growing food producing sectors in the world. It has emerged as a highly traded seafood product, currently exceeding 8 MT of high value. However, disease outbreaks, which are considered as the [...] Read more.
Shrimp, as a high-protein animal food commodity, are one of the fastest growing food producing sectors in the world. It has emerged as a highly traded seafood product, currently exceeding 8 MT of high value. However, disease outbreaks, which are considered as the primary cause of production loss in shrimp farming, have moved to the forefront in recent years and brought socio-economic and environmental unsustainability to the shrimp aquaculture industry. Acute hepatopancreatic necrosis disease (AHPND), caused by Vibrio spp., is a relatively new farmed penaeid shrimp bacterial disease. The shrimp production in AHPND affected regions has dropped to ~60%, and the disease has caused a global loss of USD 43 billion to the shrimp farming industry. The conventional approaches, such as antibiotics and disinfectants, often applied for the mitigation or cure of AHPND, have had limited success. Additionally, their usage has been associated with alteration of host gut microbiota and immunity and development of antibiotic resistance in bacterial pathogens. For example, the Mexico AHPND-causing V. parahaemolyticus strain (13-306D/4 and 13-511/A1) were reported to carry tetB gene coding for tetracycline resistance gene, and V. campbellii from China was found to carry multiple antibiotic resistance genes. As a consequence, there is an urgent need to thoroughly understand the virulence mechanism of AHPND-causing Vibrio spp. and develop novel management strategies to control AHPND in shrimp aquaculture, that will be crucially important to ensure food security in the future and offer economic stability to farmers. In this review, the most important findings of AHPND are highlighted, discussed and put in perspective, and some directions for future research are presented. Full article
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