Emerging Viruses - FHP

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Fish Diseases

Emerging Viruses

Cutthroat trout

Adult cutthroat trout infected with Cutthroat Trout Virus show no sign of disease. Credit: David Leer, Oregon State University. (Public domain.)

The fish health research program at the Western Fisheries Research Center works with a variety of fish health laboratories across the USA to provide technical assistance that includes identification of novel viruses and development of tools for their detection. In recent years, we have obtained at least partial genomic nucleotide sequences of three +sense and one -sense RNA viruses from fish that include: [1] A virus isolated from fathead minnows in Arkansas in 1997 that was initially thought to be a rhabdovirus; however, analysis of the 26,000 bp genome revealed the agent was closest to the white bream virus reported from Germany that was proposed as a member of the novel genus Bafinivirus in the order Nidovirales. [2] The cutthroat trout virus (CTV) that was first recovered from fish in Heenan Lake California in 1988. The complete genome sequence of the original CTV isolate was determined and found to be most similar to Hepatitis E virus, a member of the genus Hepevirus in the family Hepeviridae that includes viruses from humans, birds and swine. Analysis of a 262 bp region of the genome of more than 80 isolates of CTV from trout in at least 10 states showed a high level of variation among the isolates, even from the same location and species. [3] Several isolates of virus from fathead minnows collected from Gullwing and Desert Coulee reservoirs in Montana during 2006-2009. The genome of the Gullwing isolate was most closely related to duck hepatitis A virus and human parechovirus in the family Picornaviridae. [4] A putative orthomyxovirus isolated from koi carp in California. The complete sequence for the PB1 gene of the segmented, -sense virus was determined and found to have a 43% amino acid identity with Infectious salmon anemia virus, a member of the genus Isavirus in the family Orthomyxoviridae.