title: Concentration of infectious aquatic rhabdoviruses from freshwater and seawater using ultrafiltration.
abstract: Infectious hematopoietic necrosis virus (IHNV), viral hemorrhagic septicemia virus, and spring viremia of carp virus were concentrated and detected from freshwater and seawater samples by using hollow-fiber ultrafiltration. Within 60 min, virus in a 50-L freshwater or saltwater sample was concentrated more than 70-fold, and virus retention efficiencies were consistently greater than 88%. Retention efficiency was highly dependent upon concentrations of column blocking and sample stabilization solutions. A large column with a surface area of 1.15 m2 and a filtration capacity of 5-200 L exhibited optimal viral retention when blocked with 2% fetal bovine serum (FBS) and when the samples were supplemented with 0.1% FBS. Conversely, a small column with 100-fold less surface area and a filtering capacity of 0.5-2.0 L was optimized when blocked with 1% FBS and when the samples were supplemented with 0.1% FBS. The optimized ultrafiltration procedure was further validated with water from a tank that contained IHNV-exposed juvenile sockeye salmon Oncorhynchus nerka, resulting in an average virus retention efficiency of 91.6 +/- 4.1% (mean +/- SE). Virus quantification of concentrated samples demonstrated that IHNV shedding in sockeye salmon preceded mortality; shedding of the virus was observed to increase significantly as early as 7 d postchallenge and peaked at day 14, when virus levels reached 4.87 x 10(3) plaque-forming units/mL. We conclude that ultrafiltration is a reliable and effective method for concentrating viable aquatic rhabdoviruses from large volumes of water and has application for the analysis of environmental water samples.
authors.affiliation: Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, British Columbia V9T 6N7, Canada.
authors.forename: Amelia A M
authors.initials: AA
authors.lastname: Grant
authors.forename: Eva
authors.initials: E
authors.lastname: Jakob
authors.forename: Jon
authors.initials: J
authors.lastname: Richard
authors.forename: Kyle A
authors.initials: KA
authors.lastname: Garver
mesh_terms: D000818:Animals; D005393:Fish Diseases; D005618:Fresh Water / Q000821:virology*; D012209:Rhabdoviridae / Q000502:physiology*; D018353:Rhabdoviridae Infections / Q000662:veterinary / Q000821:virology; D012474:Salmon; D012623:Seawater / Q000821:virology*; D014462:Ultrafiltration / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D017201:Virus Shedding