Differential amplification of Marek’s disease CVI988 vaccine and of wild-type isolates from organs of commercial chickens using single or duplexed probes in real-time PCR

ABSTRACTThe differentiation of Marek's disease virus (MDV)-infected and vaccinated animal (DIVA) test, based on the MDV pp38 gene was described by Baigent et al. [(2016). Real-time PCR for differential quantification of CVI988 vaccine and virulent MDV strains. Journal of Virological Methods, 233, 23-36], using similar primers and alternate probes for virulent MDV-1 and the vaccine CVI988 virus. We explored the assay’s applicability for commercial vaccines and commercial chickens, as the above-mentioned study employed tissue-cultured MDV strains and tissues from experimental trials. DNA of visceral organs and feathers of vaccinated or naturally infected chickens was used. Further, the applicability of the DIVA assay was evaluated using single or duplexed probes for the two viruses in the same amplification tube. Due to the high viral content in the commercial vaccines and in the clinical cases of MDV-1 infected commercial chickens, their examination by the MDV-1 DIVA real-time PCR was performed in one step...