Isolation And Detection Of Duck Hepatitis Virus

Twelve virus isolates were obtained through duck embryo allantoic sac inoculation from duckling liver samples collected from several provinces in China. All these ducklings were diagnosed clinically dying from duck virus hepatitis. The lethal rate of these isolates was 100 percent when inoculating 10-day-old duck embryos. When inoculating 6-day-old ducklings with these isolates, the mortality rate was among 0-100%. Dead ducklings showed the sign of opisthotonos, with swollen and punctuate hemorrhage in their livers. The ELD50 of these virus strains detected with duck embryos were among 10-7.32-10-3.5. Neutralizing test was done using standard serum against DHV type 1 serum and new serotype DHV. 7 isolates of them belonged to new serotype DHV, 2 belonged to DHV type 1, another 3 isolates were nontypable.A new serotype virus (B strain) was attenuated with duck embryos propagation and designated B20 strain.It was diluted into different concentration to immunize 1-day-old ducklings and the immunized ducklings were challenged with new serotype duck hepatitis virus in the 10th day. The result indicated that the protection rate of 20 fold dilution of B20 could reach to 100 percent. However, 100-fold dilution of B20 provided no protection effect. The serum of the immunized ducklings were collected and the antibody titer were measured by neutralizing test. The antibody level reached to the peak in 10 days old and then showed a downward trend. We can make the conclusion that B20 strain could provide protection aagainst the infection of new serotype DHV. It mey be used as the candidate vaccine strain.In addition, the new serotype DHV was inoculated to the duck embryo liver cell to culture, and the cytopathic effect was caused. The results showed that this virus was adapt to be cultured in liver cells of duck embryo. We found the liver cell culture were not suitable for the immunofluorescent detection for the cell emitted fluoresce spontaneous. Meanwhile, the kidney cell of ducklings died from experimentally infection with new serotype DHV was immunofluorescent.dyeing. The vival antigen could be detected by indirect immunofluorescent assay. We found the IFA could be used as rapid diagnostic technique for new serotype Duck Virus Hepatitis.