Molecular Analysis of Newcastle Disease Virus Isolated from A Vaccinated Layer Farm in Indonesia

Newcastle disease (ND) was first identified in Bogor, Java, Indonesia in 1926 and became major infectious in global commercial poultry which has morbidity and mortality rate up to 100%. Vaccination is one of prevention measures to control Newcastle disease virus (NDV) infection in layer poultry; however, cases of NDV infection are still reported in well vaccinated farms around the world. Molecular determination was aimed to examine genomic variation that might contribute to better control NDV infection. A Virulent NDV was isolated by egg inoculation of sample originated from a vaccinated layer farm suffering significant irreversible egg drop production. The NDV isolate was detected using rRT-PCR targeting region of matrix (M) and fusion (F) gene. Confirmation of virulence was determined by sequence analysis of partial F and hemagglutinin-neuraminidase (HN) genes. Phylogenetic analysis shows the isolate clustered within sub genotype VIIh with Indonesia NDV isolates. Identification of polybasic motif of ¹¹²RRRKR/F¹¹⁷ in the cleavage site of fusion protein confirms its virulence. Analysis of putative amino acid sequence highlighted E347K substitution in HN region, which has been reported to affect the capability of NDV in infecting vaccinated poultry. This finding indicates the urgent need of NDV molecular surveillance in vaccinated farms in larger area.