Prasanna K.S.NAZREEN FATHIMA M S2020-07-172020-07-172018http://krishikosh.egranth.ac.in/handle/1/5810149299An assembly of viruses can cause diseases in chicken and cause many economically important diseases in them. The common viruses affecting respiratory system of chicken include Infectious Bronchitis virus (IBV), Newcastle Disease virus (NDV), Fowl Pox virus (FPV), Infectious Laryngotracheitis (ILTV) and Avian Metapneumovirus (aMPV). A comprehensive study was done to detect the presence of IBV, NDV, FPV, ILTV and aMPV in chickens in Wayanad district of Kerala. The tissue samples collected from 50 dead birds and nasal swabs and serum samples from few live birds of different regions of the district were utilized for the study. The tissue samples were examined for gross lesions as well as histopathological lesions after formalin fixation and further tissue processing. Most of the clinical signs like unthriftiness, respiratory distress, gasping, sneezing and nasal discharge and lesions like pulmonary congestion, haemorrhage, thrombus, oedema and bronchial epithelial damage observed were in comparison with the lesions usually noticed in respiratory viral infections. Molecular detection was also carried out after RNA/ DNA extraction. For IBV detection, nested reverse transcription polymerase chain reaction (RT-PCR) targeting N gene region was carried out and eight samples were detected as positive giving a percentage positivity of 16 per cent. By sequencing and BLAST analysis, it was found that IBV isolate has similarity with Chinese isolates. For NDV detection, RT-PCR targeting M and F gene region were done and one sample was detected as positive (two per cent). On BLAST analysis, it was found that NDV isolates had much similarity to other Indian isolates. For FPV detection, PCR targeting 4b gene was carried out and only one sample was detected as positive. On BLAST analysis, it showed much similarity to Hungarian and Mozambique isolates. For ILTV detection, PCR targeting gB gene and for aMPV detection, RT-PCR targeting M gene was carried out and none of the samples were detected as positive. The study could successfully detect the presence of Infectious Bronchitis, Newcastle Disease and Fowl Pox in the poultry population in Wayanad district of Kerala.ennullThesis