Concentration of infectious aquatic rhabdoviruses from freshwater and seawater using ultrafiltration

• Published in: Journal of aquatic animal health Vol. 23; no. 4; p. 218
• Main Authors: Grant, Amelia A M, Jakob, Eva, Richard, Jon, Garver, Kyle A
• Format: Journal Article
• Language: English
• Published: United States 01.12.2011
• Subjects: Animals; Fish Diseases; Fresh Water - virology; Rhabdoviridae - physiology; Rhabdoviridae Infections - veterinary; Rhabdoviridae Infections - virology; Salmon; Seawater - virology; Ultrafiltration - instrumentation; Ultrafiltration - methods; Ultrafiltration - veterinary; Virus Shedding
• ISSN: 0899-7659
• DOI: 10.1080/08997659.2011.644412

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.