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

Identification and Characterization of an Exogenous Retrovirus from Atlantic Salmon Swim Bladder Sarcomas

A novel piscine retrovirus has been identified in association with an outbreak of leiomyosarcoma in the swim bladders of Atlantic salmon. The complete nucleotide sequence of the Atlantic salmon swim bladder sarcoma virus (SSSV) provirus is 10.9 kb in length and shares a structure and transcriptional profile similar to those of murine leukemia virus-like simple retroviruses. SSSV appears unique to simple retroviruses by not harboring sequences in the Atlantic salmon genome. Additionally, SSSV differs from other retroviruses in potentially utilizing a methionine tRNA primer binding site. SSSV-associated tumors contain high proviral copy numbers (greater than 30 per cell) and a polyclonal integration pattern. Phylogenetic analysis based on reverse transcriptase places SSSV with zebrafish endogenous retrovirus (ZFERV) between the Gammaretrovirus and Epsilonretrovirus genera. Large regions of continuous homology between SSSV and ZFERV Gag, Pol, and Env suggest that these viruses represent a new group of related piscine retroviruses

Genomic Variation of the Fibropapilloma-Associated Marine Turtle Herpesvirus across Seven Geographic Areas and Three Host Species

Fibropapillomatosis (FP) of marine turtles is an emerging neoplastic disease associated with infection by a novel turtle herpesvirus, fibropapilloma-associated turtle herpesvirus (FPTHV). This report presents 23 kb of the genome of an FPTHV infecting a Hawaiian green turtle (Chelonia mydas). By sequence homology, the open reading frames in this contig correspond to herpes simplex virus genes U(L)23 through U(L)36. The order, orientation, and homology of these putative genes indicate that FPTHV is a member of the Alphaherpesvirinae. The U(L)27-, U(L)30-, and U(L)34-homologous open reading frames from FPTHVs infecting nine FP-affected marine turtles from seven geographic areas and three turtle species (C. mydas, Caretta caretta, and Lepidochelys olivacea) were compared. A high degree of nucleotide sequence conservation was found among these virus variants. However, geographic variations were also found: the FPTHVs examined here form four groups, corresponding to the Atlantic Ocean, West pacific, mid-Pacific, and east Pacific. Our results indicate that FPTHV was established in marine turtle populations prior to the emergence of FP as it is currently known

Fish analyzed for VHSV and number of fish determined to be positive with data on fish sizes and known vulnerability to VHSV.

<p>1. VHSV susceptibility is reported by the U.S. Department of Agriculture, Animal and Plant Health Inspection Service <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010156#pone.0010156-Center1" target="_blank">[12]</a> although other species can be infected.</p

Distribution of VHSV positive fish in the Great Lakes from 2003 through 2008 as reported by the U.S. Department of Agriculture Animal and Plant Health Inspection Service [12] and the distribution of documented invasion hotspots [18], [27].

<p>Distribution of VHSV positive fish in the Great Lakes from 2003 through 2008 as reported by the U.S. Department of Agriculture Animal and Plant Health Inspection Service <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010156#pone.0010156-Center1" target="_blank">[12]</a> and the distribution of documented invasion hotspots <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010156#pone.0010156-Grigorovich1" target="_blank">[18]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010156#pone.0010156-Cangelosi1" target="_blank">[27]</a>.</p

Detection of VHSV in fish and water and the presence of VHSV positive fish at sampling sites in and outside of invasion hotspots shown in Figure 1.

<p>Detection of VHSV in fish and water and the presence of VHSV positive fish at sampling sites in and outside of invasion hotspots shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010156#pone-0010156-g001" target="_blank">Figure 1</a>.</p

VHSV detection in fish and water using qRT-PCR and cell culture assays shown by site, type of site, and number of fish tested.

<p>VHSV detection in fish and water using qRT-PCR and cell culture assays shown by site, type of site, and number of fish tested.</p

Distribution of VHSV positive fish and water at sites classified as commercial shipping harbors, recreational boating centers, and open shoreline.

<p>Distribution of VHSV positive fish and water at sites classified as commercial shipping harbors, recreational boating centers, and open shoreline.</p