Analytical performance characteristics and application of diagnostic tests for Namao virus in experimentally infected and wild Manitoba lake sturgeon (Acipenser fulvescens)

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Van Walleghem, Elissa
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Diseases of Aquatic Organisms
Namao virus (NV) was associated with mortality in lake sturgeon Acipenser fulvescens reared as part of a conservation stocking program for this endangered species in Manitoba, Canada. The virus itself was large, doubly encapsidated and icosahedral-shaped. Phylogenetic analyses using the major capsid protein showed that NV and other epitheliotropic sturgeon nucleo-cytoplasmic large DNA viruses shared a common evolutionary past and formed a distinct evolutionary lineage within Megavirales. Three PCR tests were developed and their analytical performance was validated for detection of these viruses. Testing of wild sturgeon revealed that NV is endemic in the Nelson River water basin in Manitoba. Bath exposure resulted in transmission of NV to healthy sturgeon. The gills appeared to be the initial site of infection with virus persisting in the head skin tissue for up to 62 days. The molecular tests will be useful tools for disease management in sturgeon conservation stocking programs.
Namao virus, NCLDV, Lake Sturgeon, Endangered species, qPCR, Diagnostic PCR, Real-time PCR, Mimiviridae
Clouthier SC, VanWalleghem E, Copeland S, Klassen C, Hobbs G, Nielsen O, Anderson ED (2013) Namao virus, a new unclassified species of nucleo-cytoplasmic large DNA virus (NCLDV) associated with mortalities in Manitoba lake sturgeon Acipenser fulvescens. Dis Aquat Org 102:195-209