Pathological and Molecular Diagnosis of Newcastle Disease in Poultry and Pigeon in Jammu Region
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Date
2018-10-24
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Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu (J&K)
Abstract
Thepresent study was doneto find the occurrence and pathology of Newcastle disease and characterization of the paramyxovirus in poultry and pigeons of Jammu region.Outbreaks amongst rural backyard poultry, commercial broiler farms and pigeon coops from August 2017 to July 2018 were attended.Disease was suspected in two flocks of backyard fowl (Gallus gallusdomesticus)showing100% morbidity and 86% mortality around RS Pura and Jammu; and in six flocks of domesticated pigeons (Columba liviadomestica) exhibiting 21.68% morbidity and 14.16% mortality around RS Pura. In fowls, principally respiratory and/or enteric clinical manifestation were observed; while in pigeons, low mortality and predominantly neurological signs were seen,and disease was probably sub-clinical in many. Gross lesions were primarily due to vascular injury, withenteric haemorrhages,haemorrhagic tracheitis and petechiaesometimes observed in other organs. No gross lesions were observed in the nervous tissue except congestion of meninges in some birds. Microscopic lesions were typical for ND and corroborating the gross lesions. Haemorrhages, mononuclear infiltration and lymphoid depletion werecommon. Lesions in nervous tissue were more pronounced in pigeons and represented focal gliosis, loss of Nissl substances and neuronal degeneration, satellitosis and neuronophagia. Consistent presence of vascular endothelial hypertrophy and perivascular oedema was noteworthy. In some cases, vacuolation was observed in some Purkinjee cells together with the possible presence of intracytoplasmic inclusions. Both fowl and pigeon isolates prepared from cloacal swabs, tissue lysate or infected allantoic fluid could haemagglutinate (HA) chicken erythrocytes. All serum collected from diseased pigeons were found to inhibit haemagglutination, confirming ND with circulating antibody titres higher than >1/16, however haemagglutination inhibition (HI) could not be done for fowls. Molecular confirmation was achieved in all clinical samples and infected allantoic fluids by amplifying a 534 bp product by Reverse Transcriptase PCR (RT-PCR) targeting a partial Fusion protein gene that includes the cleavage site routinely used for virulence characterization. Sequences were submitted in GenBank. Both fowl and pigeon isolates could be grown in chicken embryonated eggs (CEE) that resulted in embryo mortality and the allantoic fluid could be harvested for virus detection. Both fowl and pigeon virus was titrated to find the infectivity by calculating the 50 percent Embryo Infectious Dose (EID50), which was found to be 10-8.68 and 10-7.20 for fowl and pigeon isolates respectively.Virulence characterization was done by calculating the Mean Death Time (MDT) in CEE and found to be 51.43 h (Velogenic; <60 h) and 92.00 (Lentogenic; >90 h) for fowl and pigeon isolates respectively. The Intra-Cerebral Pathogenicity Index (ICPI) carried out in day-old chicks was found to be 1.51 (Velogenic; >0.7) and 0.43 (Lentogenic; <0.7) for fowl and pigeon isolates respectively. Deduction of amino acid sequence at the Fusion protein cleavage site showed a112R-R-R-K-R*F117 velogenic motif for the fowl isolate, and 112G-R-Q-G-R*L117 lentogenic motif for the pigeon isolate. Phylogenetic analysis showed that the fowl isolate clustered within genotype XIII, and pigeon isolate clustered with genotype II and vaccine strains of APMV-1, and thatboth isolates were found to be 84.1% related.
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