Characterization of Edwardsiella tarda isolated from farm-cultured eels, Anguilla japonica, in the Republic of Korea.

We surveyed the occurrence of edwardsiellosis on eel farms and investigated the characteristics of Edwardsiella tarda isolated from farm-cultured eels in the Republic of Korea. The occurrence rate of edwardsiellosis was 72% in the investigated samples. Among the edwardsiellosis cases, 46% were found to be mixed infections, with parasites and other kinds of bacteria. Some of the biochemical characteristics of the E. tarda isolates were different from those of the previously reported E. tarda isolated from several kinds of fish from different countries, especially in terms of hydrogen sulfide and indole production. The E. tarda isolated from the eels in the Republic of Korea had the characteristics of two biogroups, the wild-type biogroup and biogroup 1. The enzymatic activity of the E. tarda showed similar patterns to previously reported E. tarda strains and ATCC strains. This is the first it has been reported that E. tarda isolated from farm-cultured eels had some different biochemical characteristics from those of previously reported E. tarda isolated from several kinds of fish.

Development of duck hepatitis A virus type 3 vaccine and its use to protect ducklings against infections.

A variant type of duck hepatitis A virus (DHAV), DHAV-3 was recently discovered in South Korea and China. Sequence analyses verified that the variant is genetically or serologically different from the DHAV-1 and DHAV-2 types. Duck hepatitis had been reported in South Korea since 1985 and an attenuated DHAV-1 vaccine had efficiently prevented epidemics of DHAV-1 until 2002. Despite the DHAV-1 based vaccine in use the novel DHAV-3 circulating in South Korea remains to be a threat to duckling farming. To develop a live attenuated vaccine against DHAV-3, a representative isolate, AP-04203, was therefore attenuated by repeated passages in SPF chicken embryos 100 times. The 100th passaged virus, AP-04203P100, did not cause clinical sign and mortality in 1-day-old ducklings as well as reversion of virulence capacity. The ducklings vaccinated with AP-04203P100 virus (10(3.0)ELD(50)/0.2ml) on 1-day-old age via the intramuscular injection were well protected from 2 days after challenge with pathogenic AP04203P1 virus via the intramuscular route. In addition, the vaccine candidate also exhibited complete protection against currently circulating pathogenic DHAV-3 isolates. In conclusion, we demonstrate that the live attenuated virus, AP-04203P100, is a promising vaccine candidate facilitating the prevention of duck hepatitis caused by DHAV-3 around East Asia including South Korea.

Heterosporis anguillarum infections in farm cultured eels (Anguilla japonica) in Korea.

Ten eels (Anguilla japonica) from a fish farm in Korea were examined and diagnosed with a Heterosporis infection. The gross lesions on the trunk were uneven and the concave parts were pasty. Histopathologically, lyses of the trunk muscles, degenerative muscle fibers and the scattered spores were observed. The sporophorocyst (SPC) contained several spores with a variety of shapes. Some SPC were disrupted and the spores in the SPC were scattered in the muscle tissues. Macrophages existed near the scattered spores. Electron microscopy revealed special structures such as sporophorocyst containing various developmental parasitic stages such as meronts, sporonts, sporophorous vesicles and spores.

Synthesis and evaluation of pyrazolidine derivatives as dipeptidyl peptidase IV (DP-IV) inhibitors.

A new series of pyrazolidine derivatives was synthesized and evaluated for their ability to inhibit dipeptidyl peptidase IV (DP-IV). Compound 9i was the most active in this series, exhibited IC50 value of 1.56 microM and ED50 value of 80 mg/kg (in vivo DP-IV inhibition; po).