Differentiation of Marek's diesease virus serotypes using PCR: Research and field experience

PCR assays for serotypes 1, 2 and 3 Marek's disease virus (MDV) and their performance under experimental and field conditions, are described. The assays appear to be serotype-specific and are of broadly similar sensitivity as virus isolation and identification with immunostaining. They offer significant advantages over virus isolation in speed and cost of diagnosis, handling and storage of tissues for assay, and ability to discriminate between serotypes in mixed infections. Limitations include the ongoing requirement for invasive tissue sampling, the lack of quantification of viral load, inability to detect early MDV-1 infections in HVT-vaccinated birds and the inability to differentiate between oncogenic and attenuated vaccinal strains of MDV-1.