MOLECULAR EPIDEMIOLOGY OF MAREK’S DISEASE IN COMMERCIAL CHICKEN AND THE EXPERIMENTAL EVALUATION OF VACCINE RESPONSES
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Date
2021
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TANUVAS, CHENNAI
Abstract
The present study consists of two parts, one part was in the field condition and second part was in the experimental study. Under field condition, the molecular prevalence of MD, molecular changes in the neurovirulence factor for non-occurrence of neurological signs and MDV load in bivalent vaccinated (SB1+HVT, cell associated) birds with outbreak and without the history of outbreak were studied. A total of 285 and 60 feather follicle epithelial (FFE) samples were collected randomly from 50 vaccinated layers and 50 unvaccinated broiler farms respectively in Tamil Nadu to assess the epidemiology of the MD in different age group using Polymerase Chain Reaction (PCR). As the meq gene expression reported in all stages of pathogenesis, identification of meq denotes presence of MDV serotype 1 and it was compared with pp38 gene positivity. Among the vaccinated commercial layer, the overall prevalence of MDV was observed 50 per cent from the farms with and without history of outbreak and with current MDV outbreak as far as presence of meq gene concerned whereas pp38 gene positivity was only 16 per cent. Among broiler farms, the prevalence of MDV meq positivity was 24 per cent whereas pp38 gene positivity was only 6 per cent. All the samples with pp38 gene positivity were positive for meq gene whereas all samples with meq positivity were not shown pp38 gene positivity.