Plaque Assay of Oncorhynchus masou Virus (OMV)

Abstract

Plaque assays for salmonid virus, Oncorhynchus masou virus (OMV), were examined and compared with infectious haematopoietic necrosis virus (IHNV) and infectious pancreatic necrosis virus (IPNV), combining various fish cell-lines and three overlays.
OMV produced the plaques only in chinook salmon embryo (CHSE-214) cells and rainbow trout gonad (RTG-2) cells, irrespective of overlays used, but plaque formation of IHNV and IPNV differed in different cell-lines according to the overlays used. The plaquing procedure using CHSE-214 cells gave a ten-fold higher number of plaques than RTG-2 cells.
Among three overlays of methylcellulose, gum tragacanth, and agarose, methylcellulose overlay facilitated OMV plaque formation, and the plaques were most clearcut and easily enumerated. On the whole, the combination of methylcellulose overlay and CHSE-214 cell-line was the most suitable for plaque assay of OMV as well as IHNV and IPNV.