Host and geographic range extensions of the North American strain of viral hemorrhagic septicemia virus

Abstract

Viral hemorrhagic septicemia virus (VHSV) was isolated from populations of Pacific sardine Sardinops sagax from the coastal waters of Vancouver Island, British Columbia, Canada, and central and southern California, USA. The virus was also isolated from Pacific mackerel Scomber japonicus in southern California, from eulachon or smelt Thaleichthys pacificus, and surf smelt Hypomesus pretiosus pretiosus from Oregon, USA. Mortality and skin lesions typical of viral hemorrhagic septicemia in other marine fish species were observed among sardine in Canada and in a few surf smelt from Oregon, but the remaining isolates of VHSV were obtained from healthy appearing fish. The prevalence of VHSV among groups of apparently healthy sardine, mackerel and smelt ranged from 4 to 8% in California and Oregon. A greater prevalence of infection (58%) occurred in groups of sardine sampled in Canada that sustained a naturally occurring epidemic during 1998-99. A captive group of surf smelt in Oregon exhibited an 81% prevalence of infection with clinical signs in only a few fish. The new isolates were confirmed as North American VHSV and were closely related based on comparisons of the partial nucleotide sequence of the glycoprotein (G) gene. The VHSV isolates from sardine in Canada and California were the most closely related, differing from isolates obtained from other marine fish species and salmonids in British Columbia, Canada, Alaska and Washington, USA. These new virus isolations extend both the known hosts (sardine, mackerel and 2 species of smelt) and geographic range (Oregon and California, USA) of VHSV.

Chronic and persistent viral hemorrhagic septicemia virus infections in Pacific herring

“…obs.). Water temperature is likely an important determinant of VHS trajectory because persistence of infection in rainbow trout is inversely related to temperature (Vestergård Jørgensen 1974, 1982a, and VHSV isolations from wild fish populations tend to occur during periods of low water temperature (Meyers & Winton 1995, Amos et al 1998, Hedrick et al 2003, Altuntas & Ogut 2010 Cumulative mortality (%)…”

“…Widespread in the NE Pacific Ocean, viral hemorrhagic septicemia virus (VHSV) is a rhabdovirus that is highly virulent for Pacific herring Clupea pallasii, Pacific sardines Sardinops sagax, Pacific sandlances Ammodytes hexapterus, and other forage fishes, frequently causing disease (VHS) and mass mortalities in free-ranging populations (reviewed by Hedrick et al 2003). Once exposed, laboratory stocks of Pacific herring typically experience acute disease followed by rapid mortality (Kocan et al 1997), and epizootics in the wild are likely initiated as a result of a combination of environmental stressors and concentration or amplification mechanisms associated with viral shedding from infected individuals within a school (Hershberger et al 2010a).…”

“…obs.). Water temperature is likely an important determinant of VHS trajectory because persistence of infection in rainbow trout is inversely related to temperature (Vestergård Jørgensen 1974, 1982a, and VHSV isolations from wild fish populations tend to occur during periods of low water temperature (Meyers & Winton 1995, Amos et al 1998, Hedrick et al 2003, Altuntas & Ogut 2010 Cumulative mortality (%)Days after second exposure (Table 1); conversely, only 5.5% (6/109) of the VHSV-positive herring would have been misdiagnosed as negative by sampling only brain tissues. Additionally, VHSV titers in the brain of infected Pacific herring were generally as high as or higher than those in kidney/spleen pools, a pattern of viral tropism that is similar to reports of chronic and neurotropic forms of VHS in European rainbow trout VHS (Smail 1999).…”

Hypotheses concerning the decline and poor recovery of Pacific herring in Prince William Sound, Alaska

“…Viral hemorrhagic septicemia virus (VHSV) infects Pacific herring and other marine fish species along the west coast of North America (Meyers et al 1994;Hedrick et al 2003). Recent studies suggest that VHS is primarily a disease of age-0 herring and that the disease is either rapidly resolved or fatal within 2 weeks following infection (Kocan et al 2001;Hershberger et al 2007;Elston and Meyers 2009).…”

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“…Since then VHS was reported in various marine fishes in Europe (Mortensen et al, 1999;Schlotfeldt, 1991), including anadromous salmon (Winton et al, 1989) and marine fish in North America (Meyers and Winton, 1995;Smail, 1999). VHSV detected also in the Great Lakes region of North America (Elsayed et al, 2006) and North Atlantic coast of Canada (Gagne et al, 2007 wide range of wild marine species in Japan, Europe and North America (Hedrick et al, 2003;Mortensen et al, 1999;Takano et al, 2000). In 2004, the first outbreak of VHSV has occurred in a turbot (Psetta maxima) hatchery in Trabzon, Turkey.…”