EVALUATION OF A BACTERIOPHAGE-RELATED CHIMERIC MARINE VIRUS ASSOCIATED WITH ABALONE MORTALITY IN TAIWAN

摘要

In the past few years, a low-rate but persistent mortality was noted in the cultured abalone in the farms. This disease affected abalone reared in the summer, and resulted in an 80% cumulative mortality in the farms. The histopathology revealed various extensive fragmentation, hyaline degeneration and necrosis of the myofibers accompanying with moderate degree of hemocyte infiltration in the foot muscle. A negative-contrast electron microscopy was unable to detect viral particles from pooled tissues.No virions were observed via the electron microscopy using direct negative staining of pooled organs. Moribund abalones were performed DNA extraction, purified and DNA sequencing. These sequenced fragments had 3370/3378 (99%), 5666/5704 (99%) and 5945/5961 (99%) identities to abalone shriveling syndrome-associated virus of China isolate. Primer sets designed from the sequences of Taiwan isolate was able to amplify a 693 bp from moribund abalone. In this study, a retrospective study by using PCR revealed that 30% (12/48) of clinical chronic mortality cases had carried bacteri-ophage-related chimeric marine virus. Tissues from field cases of chronic mortality were applied in in situ hybridization, but without significant signal detected. Thus, etiologyof mortality cases remained elusive.