Additional Evidence that Juvenile Oyster Disease Is Caused by a Member of the Roseobacter Group and Colonization of Nonaffected Animals by Stappia stellulata -Like Strains

Abstract

Juvenile oyster disease (JOD) causes significant annual mortalities of hatchery-produced Eastern oysters, Crassostrea virginica, cultured in the Northeast. We have reported that a novel species of the ␣-proteobacteria Roseobacter group (designated CVSP) was numerically dominant in JOD-affected animals sampled during the 1997 epizootic on the Damariscotta River, Maine. In this study we report the isolation of CVSP bacteria from JOD-affected oysters during three separate epizootics in 1998. These bacteria were not detected in nonaffected oysters at the enzootic site, nor in animals raised at a JOD-free site. Animals raised at the JOD enzootic site that were unaffected by JOD were stably and persistently colonized by Stappia stellulata-like strains. These isolates (designated M1) inhibited the growth of CVSP bacteria in a disk-diffusion assay and thus may have prevented colonization of these animals by CVSP bacteria in situ. Laboratory-maintained C. virginica injected with CVSP bacteria experienced statistically significant elevated mortalities compared to controls, and CVSP bacteria were recovered from these animals during the mortality events. Together, these results provide additional evidence that CVSP bacteria are the etiological agent of JOD. Further, there are no other descriptions of specific marine ␣-proteobacteria that have been successfully cultivated from a defined animal host. Thus, this system presents an opportunity to investigate both bacterial and host factors involved in the establishment of such associations and the role of the invertebrate host in the ecology of these marine ␣-proteobacteria.Juvenile oyster disease (JOD) refers to a syndrome of unknown origin that results in seasonal mortalities of hatcheryproduced juvenile Crassostrea virginica raised in the northeastern United States (9,11,17). While the severity of the annual epizootics has been variable since they first appeared in the late 1980s, mortalities in some years have exceeded 90% of total production at JOD enzootic sites in Maine, Massachusetts, and New York (9,11,39,40). Typical external signs of JOD include a reduction in growth rate, the development of fragile and uneven shell margins, and cupping of the left valve. Internally, signs of JOD usually include mantle retraction and lesions and proteinaceous deposits (conchiolin) on the inner shell surfaces (9,11,17). Such signs usually appear within 4 to 6 weeks after deployment of seed at enzootic sites, and they immediately precede mortality events during which losses may exceed 50% of total production in a single week (3, 7).Several hypotheses concerning the etiology of JOD have been explored, and evidence indicates that the disease is infectious rather than due to nutritional and/or abiotic factors (9). Although no obvious agent has been identified in histological samples (9,15,39,40), the pathology and correlating environmental factors (e.g., warm temperatures and moderate salinity) have led to investigations of a possible bacterial (9, 18, 31) or protistan etiology (14,33,44)...

Physiological, Ecological, and Phylogenetic Characterization of Stappia , a Marine CO-Oxidizing Bacterial Genus

“…Stappia aggregata and Stappia sp. strains CV902-700 and CV812-530 were obtained from the Damariscotta River, Maine (2). Stappia sp.…”

“…Stappia stellulata and Stappia aggregata were originally isolated from coastal marine water column and sediment samples, assigned to the genus Agrobacterium, and subsequently transferred to the genus Stappia (1,29,38). Stappia alba (27), Stappia marina (9), and various Stappia-like isolates have since been obtained from numerous widely distributed sources, including warm temperate surface and permanently cold deep-sea waters, sediments, phytoplankton, macroalgae, invertebrates, and salt marshes (2,3,5,9,13,17,26,27,33; Donachie et al, unpublished data). In addition, the presence of Stappia or Stappia-like taxa in a similar range of habitats has also been inferred from cultivation-independent analyses (3,26;Donachie et al,unpublished).…”

Jannaschia helgolandensis gen. nov., sp. nov., a novel abundant member of the marine Roseobacter clade from the North Sea

“…Phylogenetic analysis revealed that the strains were members of the a-subclass of the Proteobacteria and were associated with the 'Roseobacter-Sulfitobacter-Silicibacter' group. Their nearest phylogenetic neighbours were Ketogulonicigenium vulgare (94?4 % similarity) and the currently unclassified strains CV919-312 (Boettcher et al, 2000) and SFR3 (L. Giuliano, M. DeDomenico, E. DeDomenico, M. Höfle and M. M. Yakimov, unpublished accession no. AJ002565), showing respective similarity values of 95?3 and 94?3 %.…”

“…Strains belonging to the 'Roseobacter-Sulfitobacter-Silicibacter' group have been isolated from various environments including marine bacterioplankton, both coastal areas and the open ocean, from Antarctica (Gosink et al, 1997;Labrenz et al, 2000;Söller et al, 2000), hypersaline environments (Labrenz et al, 1999(Labrenz et al, , 2000 and black smokers (Yurkov & Beatty, 1998b). Some strains are suspected of being specifically associated with marine invertebrates (Ruiz-Ponte et al, 1998Boettcher et al, 2000;Grigioni et al, 2000;Barbieri et al, 2001) or can colonize surfaces rapidly (Lafay et al, 1995;Prokic et al, 1998;Dang & Lovell, 2000). There are symbioses between marine algae and 'RoseobacterSulfitobacter-Silicibacter' group species where molecular evidence for co-evolution has been described (Ashen & Goff, 2000).…”

Characterization of abalone Haliotis tuberculata–Vibrio harveyi interactions in gill primary cultures

“…Bacterial diseases like Brown Ring disease (BRD) and Juvenile oyster disease (JOD) caused high mortalities in hatcheries and were commonly described in larval and adult bivalves (Lauckner 1983;Paillard et al 2004;Paillard and Maes 1989;Boettcher et al 1999Boettcher et al , 2000. Summer mortalities caused by Vibrio bacterial strains have recently been described in various cultured mollusc as the Pacific oyster Crassostrea gigas (Le Roux et al 2002;Saulnier et al 2010) and the European abalone Haliotis tuberculata .…”