Marhaver KL, Edwards RA, Rohwer F.. Viral communities associated with healthy and bleaching corals. Environ Microbiol 10: 2277-2286

Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0202, USA.
Environmental Microbiology (Impact Factor: 6.2). 06/2008; 10(9):2277-86. DOI: 10.1111/j.1462-2920.2008.01652.x
Source: PubMed


The coral holobiont is the integrated assemblage of the coral animal, its symbiotic algae, protists, fungi and a diverse consortium of Bacteria and Archaea. Corals are a model system for the study of symbiosis, the breakdown of which can result in disease and mortality. Little is known, however, about viruses that infect corals and their symbionts. Here we present metagenomic analyses of the viral communities associated with healthy and partially bleached specimens of the Caribbean reef-building coral Diploria strigosa. Surprisingly, herpes-like sequences accounted for 4-8% of the total sequences in each metagenome; this abundance of herpes-like sequences is unprecedented in other marine viral metagenomes. Viruses similar to those that infect algae and plants were also present in the coral viral assemblage. Among the phage identified, cyanophages were abundant in both healthy and bleaching corals and vibriophages were also present. Therefore, coral-associated viruses could potentially infect all components of the holobiont--coral, algal and microbial. Thus, we expect viruses to figure prominently in the preservation and breakdown of coral health.

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Available from: Kristen Marhaver
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    • "As outlined above, the coral holobiont consist of unicellular algae, fungi, protists, bacteria, archea, and viruses. Indeed, corals are part of this symbiotic relationship that comprises so many different species (Marhaver et al. 2008). The above makes it obvious that there are multiple symbiotic interactions at work in a coral colony, which can be clearly differentiated into mutualistic, aggressive and defensive properties (Van Veghel et al. 1996, Hay 1997). "

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    • "VLP abundance and VBR in seawater have been shown to increase with proximity to healthy corals (Seymour et al. 2005), albeit not to the same extent seen with diseased corals by Patten et al. (2006). Marhaver et al. (2008) carried out metagenomic analyses of viral consortia associated with the coral Diploria strigosa and they were found to be highly diverse (healthy colonies were predicted to contain over 28 000 viral types). A diverse viral consortium is to be expected, given the range of potential hosts within the coral holobiont. "
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    ABSTRACT: Coral-associated viruses are a component of the coral holobiont that have received attention only relatively recently. Given the global increase in the prevalence of coral disease, and the lack of positively identified etiological agents for many diseases, these virus consortia require increased investigation. Little is known about the viruses that are naturally associated with coral reefs and how they are affected by the local environment. In the present study, a short-term analysis of viral consortia associated with the coral Montipora capitata in Kaneohe Bay, Hawaii, USA, was carried out to determine the environmental factors influencing their composition. Coral surface microlayer (CSM) and seawater samples collected at 4 sites with a range of environmental characteristics were analyzed using transmission electron microscopy (TEM), and relative abundances of virus-like particle (VLP) morphotypes were correlated with environmental measurements. Relative proportions of several CSM-associated VLP types, including phages and filamentous VLPs, were correlated with water temperature, turbidity and chlorophyll a levels. In seawater samples, turbidity and temperature showed the strongest correlation, altering the proportion of Podoviridae-like, Geminiviridae-like and putative Archaeal viruses, among others. Overall VLP consortium composition differed significantly between the CSM and seawater only at the more de graded sites, suggesting that human activity may be affecting coral reef-associated virus consortia.
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    • ") to NCBI's RefSeq Virus database (ranging from 1% to 45% of the data set) were dsDNA and ssDNA bacteriophages (Dinsdale et al., 2008; Marhaver et al., 2008; Vega Thurber et al., 2008; Correa et al., 2013). The dominance of bacteriophages in these data sets is not surprising as these likely infect members of the rich bacterial communities associated with the coral mucus layer, gastric cavity and the coral tissue (Ducklow and Mitchell, 1979; Rohwer et al., 2002; Sweet et al., 2011; Agostini et al., 2012). "
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    ABSTRACT: Reef-building corals form close associations with organisms from all three domains of life and therefore have many potential viral hosts. Yet, knowledge of viral communities associated with corals is barely explored. This complexity presents a number of challenges in terms of the metagenomic assessments of coral viral communities, and requires specialised methods for purification and amplification of viral nucleic acids, as well as virome annotation. In this mini-review, we conduct a meta-analysis of the limited number of existing coral virome studies, as well as available coral transcriptome and metagenome data, to identify trends and potential complications inherent in different methods. The analysis shows that the method used for viral nucleic acid isolation drastically affects the observed viral assemblage and interpretation of the results. Further, the small number of viral reference genomes available, coupled with short sequence read lengths might cause errors in virus identification. Despite these limitations and potential biases, the data show that viral communities associated with corals are diverse, with double- and single-stranded DNA and RNA viruses. The identified viruses are dominated by dsDNA-tailed bacteriophages, but there are also viruses that infect eukaryote hosts, likely the endosymbiotic dinoflagellates, Symbiodinium spp., host coral, and other eukaryotes in close association.
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