Journal of Animal Health and Production

Research Article
J. Anim. Health Prod. 9(s1): 90-96
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Ahmed A. H. Ali1, Fatma Abdallah1*, Ahmed Abdelaziz2, Yahia Madbouly3, Gamilat Kotb1

1Department of Virology, Faculty of Veterinary Medicine, Zagazig University, 44511, Zagazig, Egypt; 2Free Veterinarian graduated from Mansoura University; 3Poultry Viral Vaccines Research Department, Veterinary Serum and Vaccine Research Institute (VSVRI), Al Abbassia, Cairo, P.O 11381, Box 131, Egypt.

Abstract | Newcastle disease (ND) is a highly infectious transboundary avian notifiable disease caused by Newcastle disease virus (NDV). This study was aimed to assess the pathogenesis of two Egyptian NDV strains of different genotypes in quails based on clinical signs, gross pathology, histopathology, virus nucleic acid detection in different organs using reverse transcriptase polymerase chain reaction (RT-PCR) and virus re-isolation as well as measurement of the antibody titer in serum samples. Two week-old Japanese quails (n=90) were equally allocated into three groups, the quails in the groups A and B were experimentally inoculated via oculonasal route with 0.2 mL of 107 EID50 (embryo infectious dose 50) units of NDV VIb (EG/SR/76/CH/1967) and NDV VIId (NDV/Chicken /Egypt/1/2015) strains, respectively. Group C was kept as a control group, which received phosphate-buffered saline (PBS). Our results denoted that NDV VIId was shown to cause only very mild clinical signs with no microscopic lesions detected in different organs in contrast to the NDV VIb. Additionally, NDV VIId nucleic acid was detected only in two tissue samples (spleen and brain) of two different quails at 7 days post infection (dpi) using RT-PCR without any success in isolating the virus from these tissue samples. From our results, we suggested that the decreased pathogenicity caused by NDV VIId was correlated with limited virus replication in different organs of infected quails, although it contained multiple basic amino acids at fusion protein cleavage site.

Keywords | Newcastle disease virus, Quails, Pathogenesis, Oculonasal route, Virulence, Genotype, Egypt.