Characterization of a unclassified virus and survey for its presence in Wisconsin bluegill populations

Abstract

Bluegills (Lepomis macrochirus) are important both ecologically and as sport fish. Viral disease is a threat to bluegills and other fish species. Six viruses of bluegills have been previously described, many which are able to infect other fish species. In 2001, the La Crosse Fish Health Center (LFHC) isolated a novel bluegill virus (BLGV) collected from a bluegill kill in Montana Lake in northeastern Wisconsin. Since then, the LFHC has reported multiple presumptive BLGV isolations from 14 Wisconsin locations during routine inspections of hatchery fish and wild fish health surveys, but has had no confirmatory assay. Using BLGV genomic sequence obtained during this study, a diagnostic RT-PCR for BLGV was developed. The assay confirmed BLGV isolation from 5 of 17 locations included in a preliminary survey for the virus in Wisconsin bluegills, and the LFHC has used it to confirm more recent cell culture isolations from bluegills and black crappies from Wisconsin, Illinois, and Ohio. Analysis of the genomic sequence shows BLGV is most closely related to members of the Parechovirus genus within the family Picornaviridae. However, more analysis must be performed before we can determine if BLGV should be placed within the Parechovirus genus or within a new genus.