To investigate the significance of viruses isolated from fish affected by epizootic ulcerative syndrome (EUS), a series of viral characterization and pathogenicity studies were undertaken. Further investigation of outbreaks of EUS and non-EUS diseased fish were undertaken with regard to viral involvement.
A rhabdovirus (T9412) was demonstrated as a primary pathogen for striped snakehead fish and a combination of this virus and Aphanomyces spp. fungi appeared to produce more severe EUS disease than a single infection with the fungus. Improved virus isolation methodology resulted in higher viral recovery rates from EUS outbreaks.
The genome of the snakehead cell line associated retrovirus was fully sequenced and cloned and demonstrated to be distinct from other gene sequenced retroviruses.
The EUS associated reovirus (T9231) was shown to be a member of the genus Aquareovirus, family Reoviridae, but was a new serotype. Experimental studies with this virus in snakehead fish demonstrated non-pathogenicity. The blotched snakehead (BSN) cell line associated virus was shown to be a new member of the family Birnaviridae and was also shown to be non-pathogenic for snakehead fish. Enzyme-linked immunosorbent assays (ELISA) were developed for both the aquareovirus and the BSN virus and new cell lines developed from Asiatic snakehead fish.
A regime to remove mycoplasma contamination from cell lines was developed and demonstrated as effective.
The piscine neuropathy nodavirus was isolated from diseased spotted brown grouper from Thailand.