Comparison of Dynamics in Viremia Levels in Chickens Inoculated with Marek's Disease Virus Strains of Different Pathotypes / 中国病毒学

ABSTRACT

One-day-old unvaccinated chicks were inoculated with serotype I virulent strain GA and vaccine strain CVI988, serotype III vaccine strain HVT o f Marek's disease viruses(MDV). By using an indirect immunofluorescence assay of suspensions of peripheral blood mononuclear cells(PBMC) with monoclonal antibo dies(MAb) BA4 and BD8 specific to glycoprotein B of MDV, The dynamic course s of vir emia levels for each of 3 strains from 4 days to 45 days postinfection (PI) were determind. Viremia for virulent strain GA-infected chickens were detected from 4 days PI until days before death of infected chickens, it got its peak at abou t 14 days PI. Viremia in serotype 1 vaccine CVI988-inoculated chickens were mea sured between 4 to 22 days PI, it could be detected from 4 days PI and ended at 18 days PI, it got its peak at 8 days PI. For serotype 3 vaccine HVT-inoculated chickens, viremia could be detected beween 4 to 14 days PI, its peak happened a t about 6 days PI. Such IFA with MAbs BA4 and BD8 could be used to evaluate qu al ity of vaccination process in chicken flocks. The differential dynamic courses o f viremia for different strains may be used to diagnose virulent MDV infection i n vaccinated flocks. The viremia levels measured by IFA with the MAbs and co-cu ltivation assay for plague forming unit(PFU) were compared. The results indicate d that IFA assay of PBMC suspension was more sensitive and specific than co-cu ltivation assay, i.e. viremia levels measured by IFA were 30 to 100-fold higher than that by plague-forming assay in CEF for the same sample.