Ark Shell Research Articles

Isolation and characterization of Vibrio harveyi as a major pathogen associated with mass mortalities of ark clam, Scapharca broughtonii, in summer

Mass mortality of ark clam, Scapharca broughtonii, occurred in a local farm along the Bohai Sea, China in August 2017. Ostreid herpesvirus SB strain, which was the only pathogen previously reported in S. broughtonii, was not detected in moribund S. broughtonii. However, four kinds of bacteria were isolated from the hepatopancreas of naturally diseased S. broughtonii, and they were further identified based on 16S rDNA gene sequence analysis. These bacteria were closely related to Vibrio harveyi (A2-1), Microbulbifer variabilis (A2-2), V. alginolyticus (A2-3), and Pseudoalteromonas sp. (A2-4). Hemolysis test showed that A2-1 exhibited a strong hemolytic activity. The cumulative mortality of S. broughtonii with foot-injected A2-1 reached 100%, which was significantly higher than that of groups infected with other bacteria. Notably, temperature showed a significant effect on the mortality of S. broughtonii infected with A2-1, as the immersion challenged test showed 100% mortality occurred at 25 ± 2 °C on the 9th day, whereas no death was observed at 15 ± 2 °C on the 12th day. Temperature also significantly affected the growth rate and extracellular protein secretion of A2-1. In conclusion, this study is the first to report that V. harveyi is a pathogen that causes mass mortality in S. broughtonii, and the temperature is an important environmental factor that affects the virulence of A2–1 on S. broughtonii.

Nutritional Composition and Marketable Shelf-Life of Blood Ark Clams and Ponderous Ark Clams

The rapid growth of Florida's hard clam industry over the past decade has motivated aquaculturists to explore alternative molluscan species, which could reduce exposure to production risks and simultaneously promote market expansion. Species diversification could possibly provide some degree of protection against potential disastrous losses associated with a monoculture-based industry. Further, production of other molluscan species could potentially increase sales and profitability, expanding clam consumers' options. The Blood Ark (Anadara ovalis) and the Ponderous Ark (Noetia ponderosa) clams represent two possible production opportunities. This is EDIS document FE568, a publication of the Department of Food and Resource Economics, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL. Published August 2005.

Marketing Opportunities for Blood Ark Clams and Ponderous Ark Clams

The basic objective of this study was to determine the present market potential of Blood Ark and Ponderous Ark clams in the United States. This paper summarizes research that attempted to quantify the shellfish trade industry's present awareness and acceptance of the Blood Ark and Ponderous Ark clams as a first step in evaluating the economic feasibility of producing these clams in commercial quantities using commercially feasible aquacultural production techniques by the existing hard clam industry. This is EDIS document FE478, a publication of the Department of Food and Resource Economics, Florida Cooperative Extension Service, UF/IFAS, University of Florida, Gainesville, FL. Published August 2005.

The transcriptomic responses of the ark shell, Anadara broughtonii, to sulfide and hypoxia exposure.

Sulfide and hypoxia threaten marine organisms in various ways. Anadara broughtonii, a commercial marine bivalve in China which has great potential exposure to sulfide and hypoxia, was selected to test the responses to these stresses. Digital gene expression profile (DGE) analysis was performed on the juveniles' gills after exposed to normal condition (CG group), hypoxia (LO group), and low/high concentration of sulfide (LS/HS group, administered in hypoxia), respectively, using RNA-seq technology. A total of over 30 million clean reads were filtered from each DGE library and over 90% of them were annotated successfully. In total, 774 significant differentially expressed genes (DEGs) were detected and assigned to Gene ontology (GO) classification and KEGG Pathway enrichment analysis. The results show that many of the upregulated DEGs are related to hemoglobin, immunology, and stress responding. In the stressed A. broughtonii, cytochrome P450 and phosphoenolpyruvate carboxykinase may stimulate the glycolysis process to reduce oxygen consumption; Aminoacyl-tRNA synthetases, heat shock protein and protein disulfide isomerase probably help to maintain the genome integrity; Baculoviral IAP repeat-containing protein 2/3, mitogen-activated protein kinase and tumor necrosis factor pathways were probably responsible for protein repair, proteolysis, apoptosis and immune responses to high concentration of sulfide. Combined challenges also induced alternative oxidase and sushi repeat-containing protein, which have indistinct but probably indispensable function in invertebrates. For the first time, comprehensive transcriptome information on A. broughtonii in response to sulfide and hypoxia were provided. Our research offers new insights into the molecular mechanism behind the resistance of shellfish to sulfide and hypoxia.

Manufacture and Characterization Physical and Mechanical Properties of Bioveneer Based Ark Clam Shells Composite

Composite materials have been created for the applications of dental veneer from a mixture of raw materials : hydroxyapatite (HAp) powder from ark clam shells and epoxy resins by cold compression method with variations of composition hydroxyapatite (HAp) powder : epoxy resin (75 : 25)%wt, (80 : 20)%wt, (85 : 15)%wt, (90 : 10)%wt, dan (95 : 5)%wt. Sampling is created in three steps. The first step of ark clam shells powder is treated by smoothing it with a particle size of 200 mesh and heated at 900oC for 2 hours after it had been synthesized into hydroxyapatite (HAp) powder. The second step of the filler (hydroxyapatite powder) is mixed with dry mixing and then mixed with epoxy resin as a matrix. The third step of the homogeneous mixture is then inserted into the mold and compacted by heat to be more dense with pressure of 300 MPa or 3 ton held for 5 minutes at 27°C. The characterization results showed that the optimum composition of hydroxyapatite powder: epoxy resin (75 : 25)%wt with density value 0,1185 x 103 kg/m3, water absorption 1,163%, composed of -PO4 (phosphate), -CO3 (carbonate) and HOH groups. Mechanical properties with fracture strength 116 MPa, tensile strength 66,12 MPa, modulus of elasticity 3297,99 MPa and brinell hardness 75,87 HBR whose characterization results have met the conventional dental veneer standards.

Anesthetic Effects and Physiological Responses of Clove Oil, Lidocaine-HCl, and Tricaine Methanesulphonate on Seawater Shellfishes in Korea

This study aimed to investigate the effects of clove oil, lidocaine-HCl, and tricane methanesulfonate (MS-222) on scallop (Patinopecten yessoensis), ark shell (Scapharca broughtonii), surf clam (Pseudocardium sachalinensis), blue mussel (Mytilus edulis), granular ark (Tegillarca granosa), and shortneked clam (Ruditapes philippinarum), and to compare the anesthetic effect among three anesthetics. Induction times of clove oil, lidocaine-HCl, and MS-222 were significantly affected by concentrations of anesthetics, and decreased drastically as the concentrations of anesthetics increased (P 0.05). At each group, as the concentration of anesthetics increased, the induction time decreased (P 0.05). For each anesthetic, the longer the shell length of six species in this experiment were, the more induction time increased (P 0.05). Plasma cortisol and plasma glucose, which were measured to examine the stress response in seawater shellfishes in this experiment. Cortisol concentrations of clove oil, lidocaine-HCl, and MS-222 on six seawater shellfish were increased until 6 hrs after recovery of anesthesia (RA) and cortisol concentrations of three anesthetics on each shellfish were highest at 6 hrs after RA. At 6 hrs after RA, cortisol concentrations of MS-222 on each shellfish were higher than those of clove oil and lidocaine-HCl. Especially, cortisol concentration of granular ark at 6 hrs after RA was higher than that of the other shellfishes. At 6 hrs after RA, cortisol concentrations of three anesthetics were decreased until 48 hrs. Glucose concentrations of clove oil, lidocaine-HCl, and MS-222 on six seawater shellfish were increased until 12 hrs after RA and glucose concentrations of three anesthetics on each shellfish were highest at 12 hrs after RA. At 6 hrs after RA, glucose concentrations of MS-222 on each shellfish were higher than those of clove oil and lidocaine-HCl and glucose concentration of granular ark was higher than those of the other shellfishes as well. From 12 to 48 hrs after RA, glucose concentrations of three anesthetics were decreased.

Ark clams and relatives (Bivalvia: Arcida) show convergent morphological evolution associated with lifestyle transitions in the marine benthos

Ark clams and relatives (Bivalvia: Arcida) show convergent morphological evolution associated with lifestyle transitions in the marine benthos

OsHV-1 infection leads to mollusc tissue lesion and iron redistribution, revealing a strategy of iron limitation against pathogen.

The mass mortality of molluscs caused by OsHV-1 infection has frequently occurred worldwide in recent years. Meanwhile the interaction between OsHV-1 and its host is largely unknown. Innate immunity mainly makes up the mollusc defense system, due to the lack of adaptive immunity in invertebrates. The iron limitation strategy is an indispensable facet of innate immunity across vertebrate and invertebrate species. In this study, an iron limitation strategy was interestingly found to contribute to mollusc innate immune responses against OsHV-1 infection. Firstly, ark clams, Scapharca broughtonii, were experimentally infected with OsHV-1, and serious hyperaemia in hepatopancreases and the erosion of gills were observed post OsHV-1 infection according to a histology assay. Meanwhile, based on quantification and Prussian blue staining, the process of iron efflux from ark clams was described post OsHV-1 infection. Secondly, ferritin, as an important iron storage protein, was characterized in ark clams and showed significant iron binding activity. According to the results of an immunohistochemistry assay, ferritin was supposed to be responsible for the iron translocation in ark clams post OsHV-1 infection. Its expression level was significantly fluctuant in response to OsHV-1 infection. Finally, oxidative stress was assessed by the analyses of H2O2 content, total antioxidant capacity and MDA level post OsHV-1 infection. Supplementary iron was found to promote ROS generation and death of hemocytes in vivo. These results highlighted that microenvironment changes in the essential nutrient iron should be an important aspect of the pathogenesis of OsHV-1 disease.

Stock status of ark clams (Anadara spp.) based on dredge fishing of the east coast of Surabaya, Indonesia

Ark clams (Anadaraspp.) are one of the potential fishery resources off the East Coast of Surabaya. The purpose of this research was to determine the condition and stock status of Anadara spp. The biomass dynamic model was the method used to obtain the stock status of this species. For the estimation of biomass, starting in 1960, it continued to increase until finally it stabilized. Starting in the 2000s, the condition of the ark clam biomass began to decline. For the limit reference point (LRP), the value is expected to be about 7,215.55 tons with a catch effort (fmsy) of 334 units and with the Bmsy being 6,7121,38 ton; this includes MSY. For the condition of the stock in 2016, the catch was 1,2957 ton and the effort was 445 units. This means that the actual stock of the ark clam (Anadara spp.) off the East Coast of Surabaya exceeds the MSY, fmsy, and Bmsy. This is an indication of overfishing in the coastal area.

Impact of nighttime hypoxia on ark shell Scapharca broughtonii mortality on a semi-enclosed embayment seabed

The ark shell Scapharca broughtonii population has decreased markedly in recent years in Nanao Bay, a semi-enclosed embayment in Japan. Continuous measurement of dissolved oxygen (DO) at the bottom of Nanao Bay was performed, and S. broughtonii survival rates were investigated experimentally and in situ. In summer the DO concentration showed diel variation, with generally sufficient oxygen during the day but concentrations < 2 mg/l at night. In rearing experiments to investigate their physiological state, ark shells were placed in a tank designed to produce hypoxic conditions at night. Blood succinate levels in the ark shells increased, and all individuals were dead after 35 days. The results of the study indicate that the main cause of mortality of S. broughtonii on the seabed in Nanao Bay is hypoxia at night.

Influence of Salinity on Physiological Response of the Bearded Horse Mussel Modiolus barbatus and Noah’s Ark Shell Arca noae

Abstract Bearded horse mussel Modiolus barbatus and Noah’s ark shell Arca noae are a species of interest for the diversifying shellfish aquaculture on the south-eastern coast of the Adriatic. In this study, oxygen consumption (OC), total ammonia excretion (TAM) and clearance rate (CR) responses to the changes in seawater salinity (37, 30, 25 and 20) were investigated in the laboratory. There is a statistically significant influence of salinity on oxygen consumption and TAM excretion of Noah’s ark shell, while the time of exposure to different salinities is significantly correlated to TAM excretion by the bearded horse mussel. Mean OC of Noah’s ark shell ranged from 0.14 ± 0.06 to 0.54 ± 0.27 mg O2g−1h−1 and that of bearded horse mussel from 0.18 ± 0.17 to 0.26 ± 0.14 mg O2g−1h−1. Mean values of TAM excretion of Noah’s ark shell ranged from 2.14 ± 1.52 to 7.22 ± 6.04 μmol g−1 h−1 and for bearded horse mussel from 0.98 ± 0.53 to 2.78 ± 2.96 μmol g−1 h−1. Salinity and exposure time have a significant influence on the CR of Noah’s ark shell, whilst salinity has been found to be the determining factor for the bearded horse mussels’ CR. Mean values of Noah’s ark shell CR ranged from 0.96 ± 0.54 to 4.18 ± 1.15 l h−1g−1 and for bearded horse mussel from 2.43 ± 0.99 to 4.23 ± 0.84 l h−1g−1. Higher oxygen consumption to total ammonia excretion (O:N) ratios at lower salinities indicated the use of proteins as a metabolic substrate for both species. Noah’s ark shell has greater energy expenditure related to respiration and TAM excretion than the bearded horse mussel.

Identification, Characterization and Expression of Heat Shock Protein 70 in Scapharca broughtonii

As one crucial member of heat shock proteins (HSPs) family, HSP70s play many important roles in a large amount of physiological processes including immune response. However, information regarding HSP70 in ark shell Scapharca broughtonii is still rather limited. Here the full-length cDNA of HSP70 gene (named SbHSP70) of S. broughtonii was identified by using reverse transcription PCR (RT-PCR) and rapid amplification ends (RACE) methods. The SbHSP70 cDNA was 2423 bp in length containing a 5&amp;prime; untranslated region (UTR) of 131 bp, 3&amp;prime;-UTR of 330 bp, and an open reading frame (ORF) of 1962 bp which encodes a peptide of 653 amino acids.The multiple alignment and phylogeny analysis showed that the SbHSP70 shared high homology sequence with other mollusk species, and clustered together with gastropods to form a sister group. The mRNA expression profiles of SbHSP70 in tissues of foot, gill, mantle, adductor muscle, haemocytes and hepatopancreas analyzed by quantitative real-time PCR (qRT-PCR) suggested the mRNA transcripts of SbHSP70 distributed in all the examined tissues, and the highest expression level was observed in foot, and a significant difference could be detected between gill and adductor muscle (p&amp;lt;0.05), no significant difference among the gill, mantle and hemocytes (p &amp;gt; 0.05). Its dynamic change during the early stage of larvae showed that it could be transferred from parent and may be involved in some key developmental process. What&amp;rsquo;s more, Vibrio anguillarum challenge resulted in regular change of expression of SbHSP70 mRNA, indicating SbHSP70 actively participated in the immune response process.

Simulations of Recent Argon Gas-Puff Implosions on Z With Xe and Kr Dopants

An intriguing result is that a small fraction of Xe (0.8% by number in the center jet) can have a significant impact on the emitted K-shell radiation in an Ar gas-puff implosion. This result was recently obtained from a pair of experiments on Sandia National Laboratories Z machine. These shots were Z2603 (with Xe) and Z2605 (without Xe). The pair had similar initial density profiles (outer shell, inner shell, and center jet) but one had the small aforementioned percentage of Xe dopant in the center jet. The resultant Ar K-shell yield was considerably reduced from 373 ± 9% to 129 ± 9% kJ without an analogous change in the total emitted power or total radiation yield. Furthermore, the K-shell power pulse for Z2603 reduced to a broad bimodal, 7 terra watts (TW) pulse, much smaller than the 32 TW conventional single peak for Z2605. Radiation-magnetohydrodynamic simulations presented herein qualitatively reproduce major trends from experiments. Detailed analyses of the implosion dynamics, temperature and density profiles, and emitted radiation agree qualitatively with the previous study. The effect of varying the xenon fraction on K-shell radiation suggests that enhanced Xe concentration reduces K-shell emission by diminishing K-Shell radiation from the central jet.

Study of Triple Ar Gas Puff Z-Pinches on 0.9-MA, 200-ns COBRA

Ar gas puff z-pinch experiments were conducted on the 0.9-MA, 200-ns COBRA generator at Cornell University. In the experiments, a triple-nozzle gas valve was used to produce the z-pinch load with concentric outer and inner gas puffs and a central gas jet. We used a planer laser-induced fluorescence to measure the initial gas profile of the load, two four-frame 4-ns gated extreme ultraviolet cameras to image the imploding plasma, and filtered photoconducting diamond detectors to measure the X-ray output. We have observed the shock heating and/or photoionization of the dense center jet by the imploding plasma. With an outer-to-inner plenum pressure ratio of 1:3, deacceleration of the imploding plasma occurred when the outer plasma shell imploded on the inner shell resulting in a stable implosion. By varying the plenum pressure for the center jet, the X-ray emission was optimized. An Ar K-shell X-ray (3–4 keV) yield of 77 ± 17 J was produced at a current level of 0.87 ± 0.2 MA and an implosion time of 200 ns.

관상어 사육에 있어서 pH 조절 및 인산염 제거를 위한 꼬막과 굴 패각의 활용

관상어 사육에 있어서 pH 조절 및 인산염 제거를 위한 꼬막과 굴 패각의 활용

Characterization of a nucleus located mollusc mitoferrin and its response to OsHV-1 infection

Mitoferrin genes as members of SLC25 family are conservatively existed across species, mainly locate on mitochondria and serve an important role in the regulation of whole cellular iron metabolism. Available iron withholding from pathogens presents an important host defense strategy, while the regulation role of mitoferrin against invading pathogens is largely unknown. In this study, a unique mollusc mitoferrin gene was identified in ark clams, named SbmiFn, that showed conserved three-dimensional structure with other mitoferrins, and its iron binding activity was verified by iron chelating assay. Besides cytoplasmic distribution, colocalization between SbmiFn and nuclei was observed by immunohistochemistry assay. Moreover, the response of SbmiFn to viral pathogen OsHV-1 was investigated. The results showed that nucleus located signal of SbmiFn was enhanced, the expressions of SbmiFn and ferritin were coordinately decreased, which might assist host against OsHV-1 replication as the increase of OsHV-1 copies were hardly detected after that. These results refreshed our knowledge on the sequence, structure and functional characteristics of mitoferrin subfamily, and would contribute to further comparative studies on iron metabolism.

THE EFFECT OF FOOD QUANTITY ON PHYSIOLOGICAL RESPONSES OF THE BEARDED HORSE MUSSEL MODIOLUS BARBATUS AND THE NOAH’S ARK SHELL ARCA NOAE

The aim of the work was to investigate oxygen consumption, ammonia excretion, O:N ratio derived from oxygen consumption and ammonia excretion, and the clearance rate of the bearded horse mussel Modiolusbarbatus(Linnaeus, 1758) and the Noah's Ark shell ArcanoaeLinnaeus, 1758with regard to different food availability (100%, 50% and starving) during a fifteen day experiment. In this study, food quantity significantly affected ammonia excretion and O:N ratio for both species. Time spent under feeding regime resulted to increasing oxygen consumption and clearance rate values of the bearded horse mussel and the ammonia excretion values and O:N ratios of both species. Clearance rate and ammonia excretion followed a similar increasing trend over time. The consequence of increasing ammonia excretion over time was the concomitant reduction of the O:Nratio.Both species showed high values of clearance rate, an important information when choosing the farming site. Metabolic cost of respiration for starving animals was higher for M. barbatus than for A. noae, which suggests that A. noae would be a better choice for farming in oligotrophic environments.

Ostreid Herpesvirus-1 Infects Specific Hemocytes in Ark Clam, Scapharca broughtonii.

High levels of ostreid herpesvirus 1 (OsHV-1) were detected in hemocytes of OsHV-1 infected mollusks. Mollusk hemocytes are comprised of different cell types with morphological and functional heterogeneity. Granular cells are considered the main immunocompetent hemocytes. This study aimed to ascertain if OsHV-1 infects specific types of hemocytes in ark clams. Types of hemocytes were first characterized through microexamination and flow cytometry. In addition to a large group of red cells, there were three types of recognizable granular cells in ark clams. Type II granular cells were mostly found with OsHV-1 infection by transmission electron microscope (TEM) examination, and represented the hemocyte type that was susceptible to OsHV-1 infection. The subcellular location of OsHV-1 particles in apoptotic type II granular cells was further analyzed. Some OsHV-1 particles were free inside the apoptotic cells, which may contribute to OsHV-1 transmission among cells in the host, some particles were also found enclosed inside apoptotic bodies. Apoptosis is an important part of the host defense system, but might also be hijacked by OsHV-1 as a strategy to escape host immune attack. Following this investigation, a primary culture of type II granular cells with OsHV-1 infection would facilitate the research on the interaction between OsHV-1 and mollusk hosts.

Ark shell Scapharca broughtonii hemocyte response against Vibrio anguillarum challenge

Scapharca broughtonii is one of the most important Arcidae aquaculture species in the Asia-Pacific region. We aimed to investigate the immune responses of hemocytes from ark shell S. broughtonii hemolymph against pathogens. Hemocyte ultrastructure and immunological activity in response to Vibrio anguillarum challenge were observed by scanning and transmission electron microscopy. Before ultrastructure observation, we used the API ZYM semi-quantitative kit to evaluate the levels of hydrolytic enzymes in the plasma and hemocytes following V. anguillarum infection. An enzyme-linked immunosorbent assay kit was used to investigate the variation in the lysozyme activity and hemocytes following bacterial infection. The results showed that hemocytes were the main defense cells against bacterial infection, whereas plasma played a role in the transport and support of hemocytes. It was presumed that an important function of lysozymes and hydrolytic enzymes in lysosomes was for bacterial digestion. Three major types of hemocytes were observed, namely, red blood cells (RBCs), white blood cells (WBCs), and thrombocytes (TCs). Scanning electron microscopy showed that the normal RBCs appeared pie-shaped with 10 μm diameter and 4 μm central thickness, whereas WBCs were spherical in shape with varying sizes, 4–8 μm diameter, and included small lymphocytes. TCs were long, spindle-shaped, and 12–20 μm in length. The cell membrane surface was smooth and even for all cells before pathogen challenge. Under transmission electron microscopy, RBCs displayed a limited ability to devour and digest bacteria adherent to the cell surface following infection. Many hemoglobin particles were observed in the RBC cytoplasm. WBCs were very active against bacterial invasion and showed a strong ability to digest and decompose infected and wrapped V. anguillarum through phagocytosis and lysosome fusion. Digestive vacuoles rapidly became transparent and were thought to contain increasing quantities of pathogen-induced lysozymes. WBCs that devoured pathogenic bacteria were prone to deformation as well as adhesion to each other. TCs were rich in endoplasmic reticulum (ER) content in their cytoplasm and were widely connected in a net-shaped structure. Mitochondria in TCs formed clusters upon invasion of V. anguillarum in the hemolymph. TCs disintegrated to release the ER into the plasma to form a mesh that facilitated clotting. The ability of circulating hemocytes to quickly modify their morphologies and stainability suggests that S. broughtonii is endowed with highly dynamic hemocyte populations capable of coping with environmental changes and rapidly growing pathogens.

Dual transcriptomic analysis of Ostreid herpesvirus 1 infected Scapharca broughtonii with an emphasis on viral anti-apoptosis activities and host oxidative bursts

The ark shell, Scapharca (Anadara) broughtonii, is an economically important marine shellfish species in Northwestern Pacific. Mass mortalities of ark shell adults related to Ostreid herpesvirus-1 (OsHV-1) infection have occurred frequently since 2012. However, due to the lack of transcriptomic resource of ark shells, the molecular mechanisms underpinning the virus-host interaction remains largely undetermined. In the present study, we resolved the dual transcriptome changes of OsHV-1 infected ark shell with Illumina sequencing. A total of 44 M sequence reads were generated, of which 67,119 reads were mapped to the OsHV-1 genome. De novo assembly of host reads resulted in 276,997 unigenes. 74,529 (26.90%), 47,653 (17.20%) and 19, 611 (7.07%) unigenes were annotated into GO, KOG and KEGG database, respectively. According to RSEM expression values, we identified 2998 differentially expressed genes (DEGs) between control and challenged groups, which included 2065 up-regulated unigenes and 933 down-regulated unigenes. Further analysis of functional pathways indicated that OsHV-1 could inhibit host cell apoptosis mainly by the up-regulation of inhibitor of apoptosis protein (IAP), and thus facilitating its successful replication. While host hemoglobins could induce oxidative burst by suppressing its peroxidase activity, and thus defense against OsHV-1 infection. Although we reported a narrow expression of the OsHV-1 genome compared to Crassostrea gigas infection, we highlighted several common viral genes highly expressed in the two hosts, suggesting an important functional role. This study offers insights into the pathogenesis mechanisms of OsHV-1 infection in bivalve mollusks of the Arcidae family.