Investigation of Mutations in Prevalent NDV Genotype VIId in Egypt

Abstract

Virulent Newcastle disease virus Genotype VII(vNDV-VII) is one of the highly contagious viruses that affect the poultry industry in Egypt since 2010. Moreover, the disease problem has become worldwide causing severeeconomic losses. The current study aims to fully characterize seven selected virusesisolatedduring 2017-2018 from broiler flocks, have shown high mortalities (12% to 56%) and were suffering from sinusitis, severe congestion in the trachea, laryngitis, hemorrhagic ulcers in the intestine, necrosis of the spleen, and congestion of the pancreas.Theselected viruses were chosen based on their purity and absence of other co-infection to confirm the specificity of the clinical cases same as to be representative to different Egyptian governorates. The seven vNDVVII.d viruses have shown a different range of pathogenicity indexes (Mean Death Time “MDT”, and Intravenous Pathogenicity Index “IVPI”) (“54-60 hrs” and “1.4-2.26”), respectively. Furthermore, the complete F gene sequence of the sevenvirusesshowed multiple basic amino acids in the cleavage site (112RRQKRF117).Phylogenic analysis showed that the characterized viruses are belonging to velogenicNDVVII.d viruses, which is closely related (95-100%)to the previously circulating strains in Egypt. The seven isolates were also closely related to the recent recombinant ND7 vaccines (RINNOVAC Eli-7 and RINNOVAC clone G7) viruses compared to the NDV-KBNP-C4152R2L (DALGUBAL N+) virus (98-100%) and (92-96%), respectively. In conclusion, the circulated NDV viruses are related to virulent NDV genotype VII.dviruses. Furthermore, with the increase of reporting case and vaccination breaks, more focus isrequired to evaluate the recent NDV genotype VIIvaccineand adopt effective vaccination regimes in endemic regions and countries.