Vibrio areninigrae as a pathogenic bacterium in a crustacean

Ariadne Hernández-Pérez,Kenneth Söderhäll,Ratchanok Sirikharin,Pikul Jiravanichpaisal,Irene Söderhäll

doi:10.1016/j.jip.2020.107517

Ariadne Hernández-Pérez, Kenneth Söderhäll + Show 3 more

Open Access

https://doi.org/10.1016/j.jip.2020.107517

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Abstract

The occurrence of infectious diseases poses a significant threat to the aquaculture industry worldwide. Therefore, characterization of potentially harmful pathogens is one of the most important strategies to control disease outbreaks. In the present study, we investigated for the first time the pathogenicity of two Vibrio species, Vibrio metschnikovii, a foodborne pathogen that causes fatalities in humans, and Vibrio areninigrae, a bacteria isolated from black sand in Korea, using a crustacean model, the signal crayfish Pacifastacus leniusculus. Mortality challenges indicated that injection of V. metschnikovii (108 CFU/crayfish) has a mortality percentage of 22% in crayfish. In contrast, injection of P. leniusculus with 108 or 107 CFU of V. areninigrae resulted in 100% mortality within one and two days post-injection, respectively. V. areninigrae was successfully re-isolated from hepatopancreas of infected crayfish and caused 100% mortality when reinjected into new healthy crayfish. As a consequence of this infection, histopathological analysis revealed nodule formation in crayfish hepatopancreas, heart, and gills, as well as sloughed cells inside hepatopancreatic tubules and atrophy. Moreover, extracellular crude products (ECP’s) were obtained from V. areninigrae in order to investigate putative virulence factors. In vivo challenges with ECP’s caused >90% mortalities within the first 24 h. In vitro challenges with ECP’s of hemocytes induced cytotoxicity of hemocytes within the first hour of exposure. These findings represent the first report that V. areninigrae is a highly pathogenic bacterium that can cause disease in crustaceans. On the contrary, V. metschnikovii could not represent a threat for freshwater crayfish.

Highlights

Vibriosis are among the most common diseases in the aquaculture industry worldwide
One of the most important elements for pathogen emergence is the evolution of novel strains (Bayliss et al, 2017), and wild aquatic animals and water and sediment bacterial communities are considered to be the main sources of novel pathogens in aquaculture facilities (Bass et al, 2019; Feist et al, 2019)
Vibrio metschnikovii is weakly pathogenic to crayfish Crayfish injected with V. metschnikovii at concentrations of 5.6 × 108 or 5.6 × 107 colony-forming units (CFU) did not show any sign of disease

Summary

Introduction

Vibrio species are Gram-negative, bacillar in shape and motile, and ubiquitous in marine and estuarine ecosystems. This genus is one of the major bacterial species found in aquaculture farms (Cornejo-Granados et al, 2017; Holt et al, 2020), and its presence in freshwater ecosystems has been previously reported (Cornejo-Granados et al, 2018; Dong et al, 2016; Mishra et al, 2010). The occurrence of opportunistic infections in aquaculture, including vibriosis, depends on the intricate interaction of pathogens, host, and environment (Bass et al, 2019). One of the most important elements for pathogen emergence is the evolution of novel strains (Bayliss et al, 2017), and wild aquatic animals and water and sediment bacterial communities are considered to be the main sources of novel pathogens in aquaculture facilities (Bass et al, 2019; Feist et al, 2019)

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