|
An acute lethal disease of ducklngs occurred in Taiwan from 1971 to Daemler 1972. The disease was diagnosed fcc the first time as the duck virus hepatitis (DVII) by virological and pathological hniques.
Representative stains of the isolated virus, the Chiba stain of Japan, and the No. 5886 strain of the Unial States of America were pathogenic for duck kidney (DK) cell cultures as well as chicken emheyos (CE). Pljie assay methcd, which had never kenxeportlonaDVH virus, wasprovaltokeapplicabletothevirus onDKcell
Growth curve of the isolatl virus on D K culture was examined. The virus was first xsovered 3 and 4 hours aft inoculation from cell phase and fluid phase, restively. Virus titer showed logarithmic increase until 8 and 10 hours in respeDtive phase, then changed to slow increase until it reached a maximum of about 1CY’6.S PFUAn1 in both phases in72 hours at which the experiment was terminated,
Eight-day-old ducklings were inooilatl with the isolated virus intravenously ansd the virus titer of 20 organs in the dwzldings was examined chronologically. The virus was first isolani from all organs 10-36 hours inculation, and oontinned to 1e recovered from most organs until 144-216 hours. The virus was rexnered for a longer period from the epancreas and cecum and shorter from the central nervous system. The virus disappered from the serum within 43 hours aft inoculation.
The neutralizing anti&dy of ducklings inoculati with the virus intravenously was dett fO hours, then changed to gradual increase until 120 hours reaching it peak of 23. Itremainedatthis levelupto 14 days afkerincculation.
Fluorescent antigens were initially deeDel from liver 10 days and from spln 3 days inoculation. The antigens were detecnd from the thymus, pancreas, lung and rectum sometime ketween 10 to 22 hours aft inoculation. No virus was detected from trachea, bursa of Fah’icius, duodenum and cerelna.
Histological examination of the liver of inoculaal dwzklings revealed necrosis of hepatic cells accompanied by mild heterophil infiltration or hemorrhage. These changes, together with those okeerved in field cases, however, did not seem spoific for the disease.
Elerztron-micrccopic obervation of the hepatic cells in the inoculated ducldings detected degeneration of the cells and the presence of virus-like particles in the cytoplasm. The auth% However, otmld not find any clear virus particle in this study.
|