Vibrio coralliilyticus

Vibrio coralliilyticus is a Gram-negative, rod-shaped bacterium.[1] It has a polar flagellum that is used for motility and has been shown to be critical for its virulence to corals.[2] It is a versatile pathogen, impacting several marine invertebrates including Pocillopora damicornis corals (hence its name), both the Pacific and Eastern Oyster's larvae (Crassostrea gigas and Crassostrea virginica) [3][4] and some vertebrates such as the rainbow trout.[5] It is a bacterium of considerable interest given its direct contribution to temperature dependent coral bleaching[6] as well as its impacts on aquaculture where it can contribute to significant mortalities in larval oyster hatcheries.[7] There are several known virulent strains, which appear on both the Pacific and Atlantic Coasts of the United States.[4] After its initial discovery some strains were incorrectly classified as Vibrio tubiashii including the RE22 and RE98 strains but were later reclassified as Vibrio coralliilyticus.[3][7]

Vibrio coralliilyticus
Scientific classification Edit this classification
Domain: Bacteria
Phylum: Pseudomonadota
Class: Gammaproteobacteria
Order: Vibrionales
Family: Vibrionaceae
Genus: Vibrio
Species:
V. coralliilyticus
Binomial name
Vibrio coralliilyticus
Pollock et al., 2010

Pathogenicity and virulence factors

Vibrio coralliilyticus is a causative agent of both bacterially induced coral bleaching and larval oyster mortality.[4] In corals this bleaching is the result of the death of endosymbiont colonies which is mediated by V. coralliilyticus disabling Photosystem II and in some cases causing cell lysis.[4] This also seems to be exacerbated by increased virulence as a result of increasing ocean temperatures.[6] In oyster larvae an outbreak of V. coralliilyticus in a hatchery can result in mortality of up to 80%, greatly reducing hatchery production for that season leading to significant economic loss.[7] In oysters the pathogen can cause deformities of the cilia as well as disfigurements of the velum, and eventually death[4]. V. coralliilyticus also kills bacterial cells as well utilizing a Type VI secretion system to kill competitors, even out competing Vibrio cholerae cells in a bacterial killing assay.[8] V. coralliilyticus possesses a host of virulence factors that contribute to its pathogenicity. It has been found to utilize several proteases, secretion systems, hemolysins, resistance factors, and quorum sensing.[4][9] Some of the known proteases, zinc-metalloproteases, cause the previously mentioned inactivation of Photosystem II in coral photosynthetic endosymbionts (Symbiodinium)[10] leading to coral beaching. Known secretion systems include Type III, Type IV[4][11] and Type VI.[8] Spinard et al. made note of several metalloprotease and hemolysin genes in the draft genome sequence published in 2015, several of which resembled proteins of known function found in a related pathogen, Vibrio anguillarum.[11]

Treatments

Vibrio coralliilyticus has been studied quite extensively since its discovery and as such, several potential treatments for infected organisms have been proposed. In a publication by Zhao et al. in 2018 use of a probiotic organism, Phaobacter inhibens strain S4, was proposed as a potential solution to V. coralliilyticus infection in larval oysters. The S4 strain was able to inhibit production of proteases by the Vibrios and slow their growth using antibiotic compounds as well.[3]  Another proposed solution, directed towards coral pathogenicity, is the use of phage therapy to prevent the spread of the bacteria to neighboring corals.[12]

References
  1. Pollock, F. Joseph; Wilson, Bryan; Johnson, Wesley R.; Morris, Pamela J.; Willis, Bette L.; Bourne, David G. (2010). "Phylogeny of the coral pathogen Vibrio coralliilyticus". Environmental Microbiology Reports. 2 (1): 172–178. doi:10.1111/j.1758-2229.2009.00131.x. ISSN 1758-2229. PMID 23766013.
  2. Meron, Dalit; Efrony, Rotem; Johnson, Wesley R.; Schaefer, Amy L.; Morris, Pamela J.; Rosenberg, Eugene; Greenberg, E. Peter; Banin, Ehud (2009-09-01). "Role of Flagella in Virulence of the Coral Pathogen Vibrio coralliilyticus". Applied and Environmental Microbiology. 75 (17): 5704–5707. doi:10.1128/AEM.00198-09. ISSN 0099-2240. PMC 2737915. PMID 19592536.
  3. Zhao, Wenjing; Yuan, Tao; Piva, Christine; Spinard, Edward J.; Schuttert, Christian W.; Rowley, David C.; Nelson, David R. (2018-11-02). Stabb, Eric V. (ed.). "The Probiotic Bacterium Phaeobacter inhibens Downregulates Virulence Factor Transcription in the Shellfish Pathogen Vibrio coralliilyticus by N -Acyl Homoserine Lactone Production". Applied and Environmental Microbiology. 85 (2): e01545–18, /aem/85/2/AEM.01545–18.atom. doi:10.1128/AEM.01545-18. ISSN 0099-2240. PMC 6328781. PMID 30389771.
  4. Ushijima, Blake; Richards, Gary P.; Watson, Michael A.; Schubiger, Carla B.; Häse, Claudia C. (2018-06-19). Fernández Robledo, José A. (ed.). "Factors affecting infection of corals and larval oysters by Vibrio coralliilyticus". PLOS ONE. 13 (6): e0199475. doi:10.1371/journal.pone.0199475. ISSN 1932-6203. PMC 6007914. PMID 29920567.
  5. Austin, Brian; Austin, Dawn; Sutherland, Rowan; Thompson, Fabiano; Swings, Jean (2005). "Pathogenicity of vibrios to rainbow trout (Oncorhynchus mykiss, Walbaum) and Artemia nauplii". Environmental Microbiology. 7 (9): 1488–1495. doi:10.1111/j.1462-2920.2005.00847.x. ISSN 1462-2912. PMID 16104871.
  6. Ben-Haim, Yael; Zicherman-Keren, Maya; Rosenberg, Eugene (2003). "Temperature-Regulated Bleaching and Lysis of the Coral Pocillopora damicornis by the Novel Pathogen Vibrio coralliilyticus". Applied and Environmental Microbiology. 69 (7): 4236–4242. doi:10.1128/AEM.69.7.4236-4242.2003. ISSN 0099-2240. PMC 165124. PMID 12839805.
  7. Richards, Gary P.; Watson, Michael A.; Needleman, David S.; Church, Karlee M.; Häse, Claudia C. (2015-01-01). Griffiths, M. W. (ed.). "Mortalities of Eastern and Pacific Oyster Larvae Caused by the Pathogens Vibrio coralliilyticus and Vibrio tubiashii". Applied and Environmental Microbiology. 81 (1): 292–297. doi:10.1128/AEM.02930-14. ISSN 0099-2240. PMC 4272748. PMID 25344234.
  8. Guillemette, Ryan; Ushijima, Blake; Jalan, Mihika; Häse, Claudia C.; Azam, Farooq (2020-01-28). Das, Surajit (ed.). "Insight into the resilience and susceptibility of marine bacteria to T6SS attack by Vibrio cholerae and Vibrio coralliilyticus". PLOS ONE. 15 (1): e0227864. doi:10.1371/journal.pone.0227864. ISSN 1932-6203. PMC 6986712. PMID 31990915.
  9. de O Santos, Eidy; Alves, Nelson; Dias, Graciela M; Mazotto, Ana Maria; Vermelho, Alane; Vora, Gary J; Wilson, Bryan; Beltran, Victor H; Bourne, David G; Le Roux, Frédérique; Thompson, Fabiano L (2011). "Genomic and proteomic analyses of the coral pathogen Vibrio coralliilyticus reveal a diverse virulence repertoire". The ISME Journal. 5 (9): 1471–1483. doi:10.1038/ismej.2011.19. ISSN 1751-7362. PMC 3160677. PMID 21451583.
  10. Sussman, Meir; Mieog, Jos C.; Doyle, Jason; Victor, Steven; Willis, Bette L.; Bourne, David G. (2009-02-19). Bruno, John F. (ed.). "Vibrio Zinc-Metalloprotease Causes Photoinactivation of Coral Endosymbionts and Coral Tissue Lesions". PLOS ONE. 4 (2): e4511. doi:10.1371/journal.pone.0004511. ISSN 1932-6203. PMC 2637982. PMID 19225559.
  11. Spinard, Edward; Kessner, Linda; Gomez-Chiarri, Marta; Rowley, David C.; Nelson, David R. (2015-12-31). "Draft Genome Sequence of the Marine Pathogen Vibrio coralliilyticus RE22". Genome Announcements. 3 (6): e01432–15, /ga/3/6/e01432–15.atom. doi:10.1128/genomeA.01432-15. ISSN 2169-8287. PMC 4669407. PMID 26634766.
  12. Cohen, Yossi; Joseph Pollock, F.; Rosenberg, Eugene; Bourne, David G. (2013). "Phage therapy treatment of the coral pathogen Vibrio coralliilyticus". MicrobiologyOpen. 2 (1): 64–74. doi:10.1002/mbo3.52. PMC 3584214. PMID 23239510.

Further reading
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