Vibrio coralliilyticus Strain OCN008 Is an Etiological Agent of Acute Montipora White Syndrome

Abstract

dIdentification of a pathogen is a critical first step in the epidemiology and subsequent management of a disease. A limited number of pathogens have been identified for diseases contributing to the global decline of coral populations. Here we describe Vibrio coralliilyticus strain OCN008, which induces acute Montipora white syndrome (aMWS), a tissue loss disease responsible for substantial mortality of the coral Montipora capitata in Ka ne'ohe Bay, Hawai'i. OCN008 was grown in pure culture, recreated signs of disease in experimentally infected corals, and could be recovered after infection. In addition, strains similar to OCN008 were isolated from diseased coral from the field but not from healthy M. capitata. OCN008 repeatedly induced the loss of healthy M. capitata tissue from fragments under laboratory conditions with a minimum infectious dose of between 10 7 and 10 8 CFU/ml of water. In contrast, Porites compressa was not infected by OCN008, indicating the host specificity of the pathogen. A decrease in water temperature from 27 to 23°C affected the time to disease onset, but the risk of infection was not significantly reduced. Temperature-dependent bleaching, which has been observed with the V. coralliilyticus type strain BAA-450, was not observed during infection with OCN008. A comparison of the OCN008 genome to the genomes of pathogenic V. coralliilyticus strains BAA-450 and P1 revealed similar virulence-associated genes and quorum-sensing systems. Despite this genetic similarity, infections of M. capitata by OCN008 do not follow the paradigm for V. coralliilyticus infections established by the type strain.

White Syndrome-Affected Corals Have a Distinct Microbiome at Disease Lesion Fronts

“…Vibrio bacteria have been associated with white band disease (40)(41)(42) and have been shown to cause WS-like disease signs in aquarium-based infection experiments (20,(22)(23)(24). In the current study, however, we found no significant difference in the relative abundance of sequences affiliated with Vibrio bacteria between health states.…”

“…Tissue loss associated with Indo-Pacific WSs has been attributed to a number of etiological agents, including Vibrio bacteria (20)(21)(22)(23)(24), apoptosis (25), ciliates (11,26), helminths (11), viruses (27), and intraspecific chimeric parasites (11,28), suggesting that distinct and potentially distinguishable forms of WSs exist. Based on logical deduction, we contend that the WS lesions observed in this study are not the result of apoptosis or infection by Vibrio bacteria, ciliates, fungi, cyanobacteria, or helminths, because of the low levels and inconsistent presence of these organisms at WS lesion fronts.…”

Visualization of coral host–pathogen interactions using a stable GFP-labeled Vibrio coralliilyticus strain

“…Although a direct link between V. coralliilyticus and widespread coral disease outbreaks has not been definitively established, this bacterium has been implicated in coral tissue loss diseases, collectively known as white syndromes (WS), at sites across the Indo-Pacific (Ben-Haim et al 2003;Sussman et al 2008;Ushijima et al 2014). Additionally, aquariumbased infection experiments have demonstrated the ability of V. coralliilyticus to cause WS-like disease signs in several Indo-Pacific coral species (Sussman et al 2008;Vidal-Dupiol et al 2011;Ushijima et al 2014).…”

“…Although a direct link between V. coralliilyticus and widespread coral disease outbreaks has not been definitively established, this bacterium has been implicated in coral tissue loss diseases, collectively known as white syndromes (WS), at sites across the Indo-Pacific (Ben-Haim et al 2003;Sussman et al 2008;Ushijima et al 2014). Additionally, aquariumbased infection experiments have demonstrated the ability of V. coralliilyticus to cause WS-like disease signs in several Indo-Pacific coral species (Sussman et al 2008;Vidal-Dupiol et al 2011;Ushijima et al 2014). This potentially pathogenic bacterium is easy to culture, and several strains have been isolated from diseased corals that could be modified to allow specific visualization and tracking (Ben-Haim and Rosenberg 2002;Ben-Haim et al 2003;Thompson et al 2005;Sussman et al 2008;Vizcaino et al 2010;Ushijima et al 2014).…”

“…Additionally, aquariumbased infection experiments have demonstrated the ability of V. coralliilyticus to cause WS-like disease signs in several Indo-Pacific coral species (Sussman et al 2008;Vidal-Dupiol et al 2011;Ushijima et al 2014). This potentially pathogenic bacterium is easy to culture, and several strains have been isolated from diseased corals that could be modified to allow specific visualization and tracking (Ben-Haim and Rosenberg 2002;Ben-Haim et al 2003;Thompson et al 2005;Sussman et al 2008;Vizcaino et al 2010;Ushijima et al 2014). Movement patterns of this bacterium have been accurately tracked within chemical gradients mimicking the microenvironment on a coral's surface using microfluidic devices .…”