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William N. Batts

Publications and source records attributed to William N. Batts.

29 records · Page 2Linked to original sources

Molecular identification of erythrocytic necrosis virus (ENV) from the blood of Pacific herring ( Clupea pallasii )

Viral erythrocytic necrosis (VEN) is a condition affecting the red blood cells of more than 20 species of marine and anadromous fishes in the North Atlantic and North Pacific Oceans. Among populations of Pacific herring ( Clupea pallasii ) on the west coast of North America the disease causes anemia and elevated mortality in periodic epizootics. Presently, VEN is diagnosed by observation of typical cytoplasmic inclusion bodies in stained blood smears from infected fish. The causative agent, erythrocytic necrosis virus (ENV), is unculturable and a presumed iridovirus by electron microscopy. In vivo amplification of the virus in pathogen-free laboratory stocks of Pacific herring with subsequent virus concentration, purification, DNA extraction, and high-throughput sequencing were used to obtain genomic ENV sequences. Fragments with the highest sequence identity to the family Iridoviridae were used to design four sets of ENV-specific polymerase chain reaction (PCR) primers. Testing of blood and tissue samples from experimentally and wild infected Pacific herring as well as DNA extracted from other amphibian and piscine iridoviruses verified the assays were specific to ENV with a limit of detection of 0.0003 ng. Preliminary phylogenetic analyses of a 1448 bp fragment of the putative DNA polymerase gene supported inclusion of ENV in a proposed sixth genus of the family Iridoviridae that contains other erythrocytic viruses from ectothermic hosts. This study provides the first molecular evidence of ENV's inclusion within the Iridoviridae family and offers conventional PCR assays as a means of rapidly surveying the ENV-status of wild and propagated Pacific herring stocks.

Veterinary Microbiology

Universal reverse-transcriptase real-time PCR for infectious hematopoietic necrosis virus (IHNV)

Infectious hematopoietic necrosis virus (IHNV) is an acute pathogen of salmonid fishes in North America, Europe and Asia and is reportable to the World Organization for Animal Health (OIE). Phylogenetic analysis has identified 5 major virus genogroups of IHNV worldwide, designated U, M, L, E and J; multiple subtypes also exist within those genogroups. Here, we report the development and validation of a universal IHNV reverse-transcriptase real-time PCR (RT-rPCR) assay targeting the IHNV nucleocapsid (N) gene. Properties of diagnostic sensitivity (DSe) and specificity (DSp) were defined using laboratory-challenged steelhead trout Oncorhynchus mykiss, and the new assay was compared to the OIE-accepted conventional PCR test and virus isolation in cell culture. The IHNV N gene RT-rPCR had 100% DSp and DSe and a higher estimated diagnostic odds ratio (DOR) than virus culture or conventional PCR. The RT-rPCR assay was highly repeatable within a laboratory and highly reproducible between laboratories. Field testing of the assay was conducted on a random sample of juvenile steelhead collected from a hatchery raceway experiencing an IHN epizootic. The RT-rPCR detected a greater number of positive samples than cell culture and there was 40% agreement between the 2 tests. Overall, the RT-rPCR assay was highly sensitive, specific, repeatable and reproducible and is suitable for use in a diagnostic setting.

Diseases of Aquatic Organisms

Genetic analysis of a novel nidovirus from fathead minnows

A bacilliform virus was isolated from diseased fathead minnows ( Pimephales promelas ). Analysis of the complete genome coding for the polyprotein (pp1ab), spike (S), membrane (M) and nucleocapsid (N) proteins revealed that the virus was most like white bream virus (WBV), another bacilliform virus isolated from white bream ( Blicca bjoerkna L.) and the type species of the genus Bafinivirus within the order Nidovirales . In addition to similar gene order and size, alignment of deduced amino acid sequences of the pp1ab, M, N and S proteins of the fathead minnow nidovirus (FHMNV) with those of WBV showed 46, 44, 39 and 15 % identities, respectively. Phylogenetic analysis using the conserved helicase domain of the replicase showed FHMNV was distinct from WBV, yet the closest relative identified to date. Thus, FHMNV appears to represent a second species in the genus Bafinivirus . A PCR assay was developed for the identification of future FHMNV-like isolates.

Journal of General Virology

Viral hemorrhagic septicemia

Viral hemorrhagic septicemia (VHS) is one of the most important viral diseases of finfish worldwide. In the past, VHS was thought to affect mainly rainbow trout Oncorhynchus mykiss reared at freshwater facilities in Western Europe where it was known by various names including Egtved disease and infectious kidney swelling and liver degeneration (Wolf 1988). Today, VHS is known as an important source of mortality for cultured and wild fish in freshwater and marine environments in several regions of the northern hemisphere (Dixon 1999; Gagné et al. 2007; Kim and Faisal 2011; Lumsden et al. 2007; Marty et al. 1998, 2003; Meyers and Winton 1995; Skall et al. 2005b; Smail 1999; Takano et al. 2001). Viral hemorrhagic septicemia is caused by the fish rhabdovirus, viral hemorrhagic septicemia virus (VHSV), a member of the genus Novirhabdovirus of the family Rhabdoviridae

Book chapter

Detection of Viral Hemorrhagic Septicemia Virus by Quantitative Reverse Transcription Polymerase Chain Reaction from Two Fish Species at Two Sites in Lake Superior

Viral hemorrhagic septicemia virus (VHSV) was first detected in the Laurentian Great Lakes in 2005 during a mortality event in the Bay of Quinte, Lake Ontario. Subsequent analysis of archived samples determined that the first known isolation of VHSV in the Laurentian Great Lakes was from a muskellunge Esox masquinongy collected in Lake St. Clair in 2003. By the end of 2008, mortality events and viral isolations had occurred in all of the Laurentian Great Lakes except Lake Superior. In 2009, a focused disease surveillance program was designed to determine whether VHSV was also present in Lake Superior. In this survey, 874 fish from 7 sites along the U.S. shoreline of Lake Superior were collected during June 2009. Collections were focused on nearshore species known to be susceptible to VHSV. All fish were dissected individually by using aseptic techniques and were tested for the presence of VHSV genetic material by use of a quantitative reverse transcription (qRT) polymerase chain reaction (PCR) targeting the viral nucleoprotein gene. Seventeen fish from two host species at two different sites tested positive at low levels for VHSV. All attempts to isolate virus in cell culture were unsuccessful. However, the presence of viral RNA was confirmed independently in five fish by using a nested PCR that targeted the glycoprotein (G) gene. Partial G gene sequences obtained from three fish were identical to the corresponding sequence from the original 2003 VHSV isolate (MI03) from muskellunge. These detections represent the earliest evidence for the presence of VHSV in Lake Superior and illustrate the utility of the highly sensitive qRT-PCR assay for disease surveillance in aquatic animals.

Journal of Aquatic Animal Health

Distribution of an invasive aquatic pathogen (viral hemorrhagic septicemia virus) in the Great Lakes and its relationship to shipping

Viral hemorrhagic septicemia virus (VHSV) is a rhabdovirus found in fish from oceans of the northern hemisphere and freshwaters of Europe. It has caused extensive losses of cultured and wild fish and has become established in the North American Great Lakes. Large die-offs of wild fish in the Great Lakes due to VHSV have alarmed the public and provoked government attention on the introduction and spread of aquatic animal pathogens in freshwaters. We investigated the relations between VHSV dispersion and shipping and boating activity in the Great Lakes by sampling fish and water at sites that were commercial shipping harbors, recreational boating centers, and open shorelines. Fish and water samples were individually analyzed for VHSV using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and cell culture assays. Of 1,221 fish of 17 species, 55 were VHSV positive with highly varied qRT-PCR titers (1 to 5,950,000 N gene copies). The detections of VHSV in fish and water samples were closely associated and the virus was detected in 21 of 30 sites sampled. The occurrence of VHSV was not related to type of site or shipping related invasion hotspots. Our results indicate that VHSV is widely dispersed in the Great Lakes and is both an enzootic and epizootic pathogen. We demonstrate that pathogen distribution information could be developed quickly and is clearly needed for aquatic ecosystem conservation, management of affected populations, and informed regulation of the worldwide trade of aquatic organisms.

PLoS ONE

Establishment and partial characterization of a cell line from burbot Lota lota maculosa: susceptibility to IHNV, IPNV and VHSV.

This study describes the development and partial characterization of a continuous fibroblastic-like cell line (BEF-1) developed from late stage embryos of North American burbot Lota lota maculosa. This cell line has been maintained for over 5 yr and 100 passages in vitro. Cells were cultured using Eagle’s minimum essential medium with Earle’s salts (MEM) supplemented with GlutaMAX™, and 10% fetal bovine serum (FBS), pH 7.4. The addition of penicillin-streptomycin-neomycin (PSN) antibiotic mixture (0.05, 0.05, 0.1 mg ml–1, respectively) did not negatively influence cell replication; however, the antimycotic Fungizone™ (2.5 µg ml–1, amphotericin B) caused cell rounding and resulted in a severe decrease in cell proliferation. Optimal incubation temperature has been observed between 15 and 23°C, and at these temperatures cultures are routinely passed using standard trypsinization methods every 5 to 7 d at a split ratio of 1:3 or 1:4. The cell line was susceptible to isolates of the M and U North American genotypes of infectious hematopoietic necrosis virus (IHNV), and to isolates of genotypes I, IVa, and IVb of viral hemorrhagic septicemia virus (VHSV). In contrast, the cell line was refractory to infection by 2 North American isolates of infectious pancreatic necrosis virus (IPNV) from serotypes A1 and A9. This cell line provides a new laboratory tool, will allow further investigation into viral diseases of burbot and possibly other species, and is the first immortalized cell line reported from a species in the Gadidae (cod) family.

Diseases of Aquatic Organisms

Isolation and characterization of a rhabdovirus from starry flounder (Platichthys stellatus) collected from the northern portion of Puget Sound, Washington, USA

The initial characterization of a rhabdovirus isolated from a single, asymptomatic starry flounder (Platichthys stellatus) collected during a viral survey of marine fishes from the northern portion of Puget Sound, Washington, USA, is reported. Virions were bullet-shaped and approximately 100 nm long and 50 nm wide, contained a lipid envelope, remained stable for at least 14 days at temperatures ranging from -80 to 5 degrees C and grew optimally at 15 degrees C in cultures of epithelioma papulosum cyprini (EPC) cells. The cytopathic effect on EPC cell monolayers was characterized by raised foci containing rounded masses of cells. Pyknotic and dark-staining nuclei that also showed signs of karyorrhexis were observed following haematoxylin and eosin, May-Grunwald Giemsa and acridine orange staining. PAGE of the structural proteins and PCR assays using primers specific for other known fish rhabdoviruses, including Infectious hematopoietic necrosis virus, Viral hemorrhagic septicemia virus, Spring viremia of carp virus, and Hirame rhabdovirus, indicated that the new virus, tentatively termed starry flounder rhabdovirus (SFRV), was previously undescribed in marine fishes from this region. In addition, sequence analysis of 2678 nt of the amino portion of the viral polymerase gene indicated that SFRV was genetically distinct from other members of the family Rhabdoviridae for which sequence data are available. Detection of this virus during a limited viral survey of wild fishes emphasizes the void of knowledge regarding the diversity of viruses that naturally infect marine fish species in the North Pacific Ocean.

Journal of General Virology

Susceptibility of zebrafish (Danio rerio) to a model pathogen, spring viremia of carp virus

To improve our understanding of the genetic basis of fish disease, we developed a pathogen model, using zebrafish ( Danio rerio ) and spring virema of carp virus (SVCV). Replicate groups of 10 fish were acclimated to 20 or 24°C, then were exposed to SVCV concentrations of 10 3 to 10 5 plaque-forming units per milliliter (PFU/ml) of water and observed daily. In a second trial, fish were acclimated to 15°C, and replicate groups of 10 fish were exposed to SVCV at a concentration of 10 5 PFU/ml; however, the temperature was raised 1°C/wk. Moribund fish were collected for histologic examination, and dead fish were assayed for virus by use of cell culture and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Mortality exceeded 50% in fish exposed to 10 5 PFU of SVCV/ml at the lower temperatures. Clinical signs of disease became evident seven days after viral exposure and were observed most consistently in fish of the 10 5 PFU/ml groups. Affected zebrafish were anorectic and listless, with epidermal petechial hemorrhages followed by death. Use of plaque assays and RT-PCR analysis confirmed presence of SVCV at titers ≥ 10 4 PFU/g of tissue. Histologic lesions included multifocal brachial necrosis and melanomacrophage proliferation in gills, liver, and kidneys. These results indicate that zebrafish are susceptible to infection by SVCV under conditions that mimic a natural route of exposure.

Comparative Medicine

Inactivation of infectious hematopoietic necrosis virus by low levels of iodine

The fish rhabdovirus infectious hematopoietic necrosis virus (IHNV) was rapidly inactivated by extremely low concentrations of iodine in water. A 99.9% virus reduction was obtained in 7.5 s when virus (10 5 PFU/ml) and iodine (0.1 mg/liter, final concentration) were combined in distilled-deionized or hatchery water. Iodine efficacy decreased at pHs greater than 7.5 or when proteinaceous material was added to the water. Bovine serum albumin blocked iodine inactivation of the virus more effectively than did equal concentrations of fetal bovine serum or river sediment. Sodium thiosulfate effectively neutralized free iodine. Powder, iodophor, and crystalline iodine solutions inactivated IHNV equally. Iodine rapidly inactivated IHNV isolates representing each of the five electropherotypes. Under the conditions used in this study, inactivation was not affected by temperature, salinity, or water hardness. When Dworshak National Fish Hatchery water was continuously treated to provide a free iodine concentration of 0.14 mg/liter, a 7.5-s exposure to iodine was sufficient to inactivate 99.9% of the IHNV. Iodine added to water that contained IHNV prevented infection of rainbow trout ( Oncorhynchus mykiss ) fry. These results suggest that the waterborne route of IHNV transmission can be blocked by adding low iodine concentrations to the water supplies of hatcheries.

Applied and Environmental Microbiology