Search

Dot-immunoblotting assay (DIA) using five monoclonal antibodies (MAbs) to infectious bronchitis virus (IBV) was used to detect and classify the viruses propagated in embryonated chicken eggs. Using a group-specific MAb 3F5, 10 reference strains and 12 Korean isolates of IBV were successfully detected by DIA, and the lowest virus titer of IBV detected by DIA was approximately less than 10(3.8) mean embryo infective dose/ml. For evaluating the diagnostic efficiency, DIA was compared with the conventional infectious bronchitis (IB) diagnostic method. IBV antigens in allantoic fluid from embryonated eggs inoculated with IB-suspected field samples were specifically detected by DIA within only one or two egg passages, whereas the conventional embryonated egg inoculation method required four to seven egg passages for confirming IBV infection. These results indicated that DIA could significantly reduce time and cost for IB diagnosis. For examining the possibility of classifying IBV by DIA, four strain-specific MAbs, 3A4, 2A3, 6F7, and 2C6, were used. According to the MAb reacting patterns to the IBV antigens, the 10 IBV reference strains were classified into six groups; seven strains belonged to three different groups, and the other three strains each belonged to an individual group. In the case of 12 Korean isolates of IBV, they were classified in six groups. Among the six groups, the MAb reacting patterns of three groups matched those of the IBV reference strains, but the others did not. These data suggest that at least three variant serotypes of IBV exist in Korea.

Serotype 2 of Marek's disease virus (MDV) was isolated from apparently healthy birds belonging to genus Gallus that had no history of vaccination with MDV or herpesvirus of turkeys (HVT). Buffy-coat cells from these birds were inoculated onto chicken embryo fibroblast (CEF) cultures for primary isolation. Thirteen isolates from one golden pheasant and three white silky fowls, three black silky fowls, three Japanese long crowers, and three Japanese bantams produced herpes-like cytopathic effects (CPE) in the CEF cultures. Using serotype-specific monoclonal antibodies to MDV and HVT, 11 isolates were identified as serotype 2 MDV by indirect fluorescent antibody tests. The other two isolates were complicated with serotypes 1 and 3 of MDV-related viruses. Of 13 isolates, three cloned by the limiting-dilution method were further characterized as serotype 2 MDV biologically, genetically, and serologically. The results showed that the birds of the genus Gallus were naturally infected with serotype 2 MDV. This is the first report ever published about the distribution of serotype 2 MDV among healthy birds of the genus Gallus.

Quail embryo fibroblasts were used to investigate how rabbit and chicken antisera against chicken erythrocytes carrying different B alleles of the major histocompatibility antigens affect the neutralization of herpesvirus of turkeys (HVT). Although the neutralizing activities of these antisera were rather low, the HVT propagated in chicken embryo fibroblasts (CEF) from certain genotypic embryos was neutralized more by the antisera to the corresponding erythrocytes. After absorption of these antisera with homologous erythrocytes, the neutralizing activity of the absorbed sera was reduced slightly. These results reveal that the virion antigens of HVT might be partially associated with the host cell antigens of the fibroblast infected with the virus. The virus grown in these cells might incorporate the host cell antigens, including histocompatibility antigens, into the virion envelope.

In a study of outbreaks of Marek's disease in quails, 220 adult quails vaccinated with herpesvirus of turkeys (HVT) were examined pathologically and serologically for Marek's disease (MD). Forty-three of the 220 quails exhibited microscopic lesions similar to those of chickens with MD. MD-virus-specific antigen was found in feather tips of 44 of the 220 birds, and the HVT-specific antibody was found in sera of 56 of the 220 birds by agar gel precipitation. There was a positive correlation between the incidence of lymphomatous changes and the presence of MD-virus-specific antigen, and there was a negative correlation between the incidence of lymphomatous changes and the presence of antibody against HVT on a flock basis.