PCR-based detection and mutation dynamics of fusion protein gene of orthoaviula viruses sequestered during 2023 field outbreaks in Pakistan

: To isolate and detect a Newcastle disease virus in commercial poultry, Molecular characterization and phylogenetic analysis of the confirmed isolate and Multiple sequence alignment and achievement of accession numbers against our submissions in NCBI bankit.: Genetic and antigenic diversity in the fusion protein gene of New Castle disease virus strains has been recognized and the progressive changes over sequential years indicate that it is a continuously evolving virus. The current vaccines containing conventional vaccinal strains can protect birds to a certain level but do not prevent infection and virus shedding. : The partial fusion protein gene of the 14 NDV isolates during the 2023 outbreaks from different areas of Pakistan was determined and analyzed. The antigenic protein translational segment of the fusion gene nucleotide fragment was targeted with a specifically designed primer executed 202 bp size of predictable amplicon during PCR amplification. The nucleotide sequence analysis of studied isolates showed closed similarity to the NCBI bankit numbers. Phylogenetic analysis revealed that 3 isolates belong to genotype II while, 2 isolates positions near genotype VIII of class II. The 6 isolates were located near genotype XVII and only 1 was presented on genotype V branch in calss II. Mutation analysis results revealed various mutations at nucleotide intervals and even found altered amino acids during translation. The results revealed that nucleotide mutation at various positions attributes amino acid substitution that enables wild prevailing strains to evade artificial active immunity. In such a scenario Chimeric and genotype match vaccines prepared from indigenous isolates may be useful in developing candidate vaccines to prevent virus shedding and infection. Further studies are suggested at molecular level to determine the consensus amino acid sequence for virulent, mesogenic, and avirulent prevailing NDV strains.