Occurrence of Marine Birnavirus Through the Year in Coastal Seawater in the Uwa Sea.

This study aims to determine the seasonal occurrence of marine birnavirus (MABV) at a coastal site in the Uwa Sea, Japan, in 1997 and 1998. To detect MABV from seawater, a simple method was developed for concentrating MABV by dialysis and ethanol precipitation. The concentrated virus was used for polymerase chain reaction (PCR), enzyme-linked immunosorbent assay, and virus isolation. Viral genome was detected through the experimental period. The amount of PCR product varied; it was small in summer, but increased from fall to winter. Viral protein was also detected, and the amount in the January sample was equivalent to approximately 10(2) TCID(50) (50% tissue culture infectious dose) of the virus. However, infectious viruses were not isolated. This suggested that MABV was released from hosts to environmental seawater in winter and possibly degraded after release.