Prevalence of NDV-VII.1.1, Lpai-H9n2 and Hpai-H5n8 in Chickens in 2 Egyptian Governorates During Late 2020

Abstract

Newcastle disease virus (NDV) and Avian Influenza (AIV) incriminated in many respiratory disease problems and egg production decline affecting both broilers and laying hens worldwide. Isolation and identification of NDV, AIV were carried out on 50 diseased chicken (43 broiler & 7 layer) flocks collected from Damietta and Dakahlia Governorates, Egypt. Thirty eight out of 50 examined flocks (76%) showed respiratory signs [37 broiler (74%) and 1-layer (2%) flocks]. The other 12 examined flocks exhibited general signs of illness with greenish diarrhea. Samples from the examined flocks were inoculated into ECE via allantoic sac route and the collected allantoic fluids were tested for hemagglutination activity (HA) which revealed that 21 out of 50 flocks were HA positive (42%); 19 broiler (90.47%) and 2-layer (9.52%) flocks. The twenty-one HA positive samples were subsequently subjected to real-time reverse-transcriptase polymerase-chain-reaction (rRT-PCR). Fifteen samples were positive for Velogenic NDV (71.42%); 3 samples were positive for low pathogenic avian influenza (LPAI) subtype H9 (14.28%); one samples was positive for highly pathogenic avian influenza (HPAI) subtype H5 (4.76%) and 2 samples showed mixed infection for both NDV and H9N2 (9.52%). The Phylogenetic analysis identified the Velogenic NDV genotype VII.1.1 with the amino acid sequence of the three isolates fusion protein cleavage site carries motif 112RRQKRF117. The partial HA gene sequence classified the one selected LPAI-H9N2 isolate as a member of G1 lineage within group B with dibasic amino acid cleavage site motif of 333PARSSR/GLF341 which is distinctive to LPAI. While the other selected isolates of HPAI-H5 belonged to sub type H5N8 clade 2.3.4.4b with multibasic amino acid cleavage site motif of 73PLREKRRKR/GLF84 which is characteristic to HPAI. Our data highlighted the vital role of these viruses in the respiratory disease in poultry flocks. Further continuous studies are necessary for assessing new emerging strains to AIV and NDV and to discuss the impact of the co-infections of these viruses in order to learn more details for their prevention and control.Key words: Newcastle disease virus, NDV-VII.1.1, Avian Influenza virus, HPAI-H5N8, LPAI-H9N2; chicken flocks