Detection and molecular characterization of Newcastle disease virus in peafowl (Pavo cristatus) in Haryana State, India

Abstract

Present study was undertaken to investigate the cause of deaths of peafowls in Haryana State. In total, 145 birds were sick and 28 birds were reported dead during July to September 2012. Some of the sick birds were showing signs of shaking of heads, torticollis and paresis. Blood and cloacal swab samples from sick birds along with brain and intestinal tissues from dead birds were collected for further investigation. Although post-mortem examination showed no typical lesions of Newcastle disease virus (NDV) yet raised HI tires against NDV in some serum samples and clinical signs indicated the presence of NDV. One of the brain tissues (NDV/IND2012/01) from the field case was processed and adapted to Vero cell line for virus isolation. The fusion (F) gene based nested RT-PCR (RT-nPCR) confirmed the presence of NDV in all field samples and cell culture isolate. Sequencing of the partial F gene amplicons (216bp) using the PCR primers as sequencing primers confirmed the PCR results. The deduced amino acid sequences of partial F gene were found to have the amino acid motif (111)GRRQKR/F(117) in the fusion protein cleavage site (FPCS). This amino acid motif is indicative of the velogenic nature of these NDVs. Phylogenetic studies have shown that the virus belonged to class II genotype VII very closely related to virus isolates originated from outbreaks in Western Europe, Israel, Indonesia, Taiwan and India. Phylogenetic grouping of the virus and sequence of FPCS is indicative of pathogenic potential of virus strain circulating in peacocks in Haryana.