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Vibrio
Scientific classification
Kingdom:	Bacteria
Phylum:	Proteobacteria
Class:	Gammaproteobacteria
Order:	Vibrionales
Family:	Vibrionaceae
Genus:	Vibrio Pacini 1854
Species:	Vibrio anguillarum

Vibrio anguillarum is a species of Gram-negative, curved-rod bacteria with one polar flagellum . It is an important pathogen and the main causative agent of the disease known as vibriosis or red pest of eels. This disease has the ability to impact brackish water, marine water, and freshwater species and may greatly impact cultured salmonid fish. Vibriosis has been observed in salmon, bream, eel, mullet, catfish, and tilapia, amongst others. The organism is most prevalent in late summer in salt or brackish water and transmission is mainly horizontal by direct contact. It is widely distributed across the world.

To Dos:

Image of Vibrio anguillarum

Growth and Reproduction

To the control section can add predators (vibriophages) http://aem.asm.org/content/80/10/3128.full)

Genetics http://msystems.asm.org/content/2/1/e00001-17 https://standardsingenomics.biomedcentral.com/articles/10.1186/s40793-015-0060-7

Etymology (vibriosis)

Behaviour http://umu.diva-portal.org/smash/record.jsf?pid=diva2%3A517616&dswid=cookie-agreed

Metabolism

Iron uptake source: 10.1111/j.1758-2229.2009.00103.x

Morphology: This source talks about the importance of flagellum: Flagellin A is essential for the virulence of Vibrio anguillarum.

Origin and History

Vibrio anguillarum were first noted in Canada on July 22, 1968 in Nanaimo, British Columbia. These V. anguillarum were initially observed in chum salmon and later observed to have infected sockeye salmon. Despite less sockeye salmon dying as a result of V. anguillarum infection, nearly 50% of the chum salmon infected with V. anguillarum died within 96 hours. Initial observations revealed that infected fish exhibited red markings located at their throat region as well as at the base of their paired fins.

Current research dictates that there are 23 different serotypes of Vibrio anguillarum. Of these serotypes, O1, O2, and O3 are known to play the most predominant role in generating vibriosis in infected species.

Taxonomy

Vibrio anguillarum can be categorized into 16 serotypes.^[6] O-serotype systems have been the most widely used method for dividing V. anguillarum into subgroups. Grisez and Ollevier combined results from existing but differing serotype systems, to form the 16 O-serogroups.

These serotypes are characterized based on O antigen detection, using antisera, Western blots, and analysis on the varying LPS profiles.^[7] Different serotypes exhibit different parthenogenesis, and therefore have varying economic importance. Virulence factors vary between serotypes, serogroups O1 and O2 carry the most importance as fish pathogens in aquaculture and in the wild, while serogroup O3 is the group often found in infected eels. The other serotypes are rarely found in diseased fish, so are considered of lesser importance.

The genus Vibrio contains Vibrio anguillarum as well as other species that are important due to their ability to cause illness. Pathogenic strains of Vibrio include V. chloerae (which causes cholera), V. vulnificus (symptoms range from gastroenteritis, necrotizing wounds and septicemia) and V. Parahaemolyticus (primarily causes gastroenteritis).

Clinical signs and diagnosis

Multiple haemorrhages in the body and skin changes signifying systemic involvement occur. Splenomegaly (enlargement of spleen) may be evident in young fish. Diagnosis relies on culture of V. anguillarum and the use of monoclonal antibodies. Multiple haemorrhages in the body and skin changes signifying systemic involvement occur. Splenomegaly (enlargement of spleen) may be evident in young fish. Diagnosis relies on culture of V. anguillarum and the use of monoclonal antibodies. V. anguillarum causes haemorrhagic septicaemia in a broad range of fish, which can presents clinically as expohthalmia (bulging eyes), whitening of the corneas, softening of the spleen, and large hemorrhages on the liver and the base of the fins.

Ecology

Vibrio anguillarum have optimal growth temperatures between 30°C and 34°C. Growth rates are found to be increasing with temperature with a maximum growth temperature at 38.5°C. They are Halophiles but growth is more dependent on temperature than salinity. Lethal temperatures and salinity are at values greater than 41°C and 7%. The efficacy of Binary fission of Vibrio anguillarum cells are dependent on the pH levels of their surroundings. Binary fission is inhibited at pH greater than 9, disrupted at pH 6 or below, and most efficient at pH 7. They are more common in environments producing fertilized fish eggs with inhabitants such as larval fish or rotifers. Environments containing divalent cations allow Vibrio anguillarum to thrive in.

Societal Impacts

The economic wellbeing of larviculture and aquacultural markets worldwide can be impacted by Vibrio anguillarum as this species may drastically increase mortality rates in freshwater and marine water organisms such as salmon. Fisheries and Oceans Canada reported that Canada exported an estimated $6.6 billion worth of seafood and fish products in 2016 alone. Meanwhile, more than $1 billion in GDP was generated by the Canadian aquaculture market in 2015 and employed approximately 72,000 workers.

Pathogen and Virulence

Vibrio anguillarum can either attach to the host surface cells by absorbing their mucus or by penetrating through the epithelial and vascular tissue. The adhesiveness of Virbio anguillarum is dependent on the functionality of their exopolysaccharide which is encoded by the hfq gene. Exopolysaccharide transport system utilizes the fish's (host) natural mucus shedding mechanism by its integument system to remain attached to the host. The adhesive ability is not dependent on the flagella but in order for V.anguillarum, the flagella's function must be maintained. The presence of a flagellum enables species as the Vibrio anguillarum to infect other organisms with greater efficiency. Research has found that flagellum may assist with adhesion and/or mobility which are important in virulence as they may enable infective species to dominate. Within the sheath of a Vibrio anguillarum's flagellum, antigens, such as Lipopolysaccharides (LPS), may be stored . LPS, in turn, may assist Vibrio anguillarum with infection following entry into the target species

Treatment and control

Treatment measures such as the addition of soluble mixture halquinol have been shown to inhibit growth of Vibrio anguillarum in the presence of fish. Another treatment includes increasing the temperature to 44°C for 3 minutes or 47.5°C for 2 minutes. The addition of 1 mg/L ozone has been shown to completely destroy the presence of Vibrio anguillarum. Mortality from vibrio anguillarum infection can be reduced with the continual addition of anti-microbial peptides (cecropin-bee melittin hybrid peptide, CEME and pleurocidin amide). Mortality can also be reduced with changes to aquaculture feed such as adding selenium, antibodies from hen egg yolks, or oregano-derived carvacrol as feed additives. The addition of antagonistic bacteria can be used to prevent the attachment of Vibrio anguillarum enterocytes. The use of probiotics such as V. alginolyticus, Vagococcus fluvialis, Pseudomonas fluorescens AH2, and extracellular proteins from Kocuria spp., and Rhodococcus spp. has shown to reduce mortality by Vibrio anguillarum infection.

Vaccinations have also shown to work by administering Vibrio anguillarum killed by heat or formaldehyde into fish cultures. Other ways to administer dead Vibrio anguillarum is by adding it into feed as wet-packed whole cell or lyophilized whole-cell bacterin. Another way is to place fish cultures into muscle and vaccine containing immersion solution before sending off to aquaculture pools. Monoclonal anti-idiotype antibodies as surrogate antigen can be used instead of administering dead Vibrio anguillarum. Another type of vaccine is through the use of adhesion proteins from the outer-membrane of Aeromonas hydrophila. Other vaccine types include the addition of live-attenuated Vibrio anguillarum that are mutated or plasmid free Vibrio anguillarum.

Oral vaccines have been proven to be ineffective due to the fact that the gastric fluid in the upper intestine will inactivate components in the vaccine.

Further reading

Frans, I; Michiels, C W (2011). "Vibrio anguillarum as a fish pathogen: virulence factors, diagnosis and prevention". Journal of Fish Diseases. 34 (9): 643–661. doi:10.1111/j.1365-2761.2011.01279.x.

Jang, I K; Qiao, G (Oct 2014). "Effect of multiple infections with white spot syndrome virus and Vibrio anguillarum on Pacific white shrimp Litopenaeus vannamei (L.): mortality and viral replication". Journal of Fish Diseases. 37 (10): 911–920. doi:10.1111/jfd.12194. PMID 24127689.

External links

• Type strain of Vibrio anguillarum at BacDive - the Bacterial Diversity Metadatabase

Category:Bacterial diseases of fish Category:Bacteria described in 1854