Author
PANDARANGGA, PUTRI - University Of Georgia | |
Susta, Leonardo | |
MOURA, VERIDIANA - US Department Of Agriculture (USDA) | |
BROWN, CORRIE - University Of Georgia | |
Miller, Patti | |
CARDENAS GARCIA, STIVALIS - University Of Georgia | |
Afonso, Claudio |
Submitted to: American College of Veterinary Pathologists Meeting
Publication Type: Abstract Only Publication Acceptance Date: 9/11/2014 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Newcastle disease (ND) is a devastating disease of poultry worldwide caused by virulent strains of Newcastle disease virus (NDV). New strains of NDV frequently emerge, creating challenges for disease control. Since 2012, NDV strains of new genotype VIIi have been reported in Israel and Pakistan, becoming more prevalent than the previously circulating genotypes VIId (Israel) and XIIIa (Pakistan). In this study, one NDV strain from Israel (APMV1/Broiler-Breeders/Israel (Kvuzat-Yavne)/NDV/826/2013 [I-826]) and one from Pakistan (APMV1/chicken/SPVC/Karachi/NDV/33/2007 [Karachi 33]), were characterized by phylogenetic analysis, ICPI (intra-cerebral pathogenicity index), and clinico-pathological assessment. Phylogenetic analysis carried out with the full coding sequence of the fusion (F) gene revealed that I-826 and Karachi33 belong to genotype VIIi and genotype XIII, respectively. Both viruses had a polybasic configuration of the F cleavage site and high ICPI values, classifying these strains as virulent NDV by international standards. Groups of 4-week-old White Leghorn chickens were inoculated in the right conjunctival sac and choanal slit with 105.5 EID50 (Embryo Infectious Dose 50%) units of virus. Viruses caused 100% mortality within day 4 (I-826) and 5 (Karachi33) post-infection. Gross and histologic lesions in all infected birds included extensive necrosis of lymphoid tissues (spleen, thymus, Bursa of Fabricius, cecal tonsils, gut-associated lymphoid tissue), segmental necrosis and hemorrhage in the small and large intestine, and eyelid edema and hemorrhages. As shown by immunohistochemistry for NDV nucleoprotein, both strains had systemic distribution, with the most intense and widespread signal in lymphoid organs and mucosa-associated lymphoid tissues. Results of the animal experiment suggest that both I-826 and Karachi33 behaved as velogenic viscerotropic NDV strains. |