Molecular pathogenic and host range determinants of reassortant Egyptian low pathogenic avian influenza H9N2 viruses from backyard chicken

Abdelhafez Samir,Amany Adel,Abdelsatar Arafa,Hesham Sultan,Hussein A Hussein Ahmed

doi:10.1080/23144599.2019.1637046

Abstract

ABSTRACTSince the introduction of H9N2 low pathogenic avian influenza virus in Egypt, it became an endemic disease causing considerable economic losses in different poultry sectors especially in the presence of other secondary bacterial and viral infections. The H9N2 viruses in Egypt are in continuous evolution that needs deep analysis for their evolution pattern based on the genetic constitutions of the pathogenic determinant genes (HA, PB2, PB1, PA, and NS). In this work, samples were collected from the backyard chickens from 3 Egyptian governorates. Five selected viruses were sequenced and analyzed for the hemagglutinin gene which showed genetic relatedness to the Asian G1 lineage group B, similar to the circulating H9N2 viruses in Egypt since 2013. The sequence for PB2, PB1, PA, HA and NS genes of the selected five viruses indicate a natural re-assortment event with recent Eurasian subtypes and similar to Egyptian H9N2 virus isolated from pigeon in Egypt during 2014. The Egyptian viruses of our study possess amino acids signatures including S42, V127, L550, L672 and V504 in the internal genes NS1, PA, and PB2, of respectively of an impact on virus transmission and replication. This work indicates that the H9N2 is in continuous evolution with alarming to the reassortment occurrence.

Highlights

The low pathogenic avian influenza viruses of H9N2 subtype have become worldwide enzootic in the poultry population since its first detection in turkeys during 1966 [1,2,3] causes asymptomatic or mild disease in domestic poultry, which usually goes unnoticed
Quail and pigeon are considered as important reservoirs for the H9N2 viruses, as shown in China that they are serving as a linkage between waterfowl and terrestrial avian species [9]
Both quail and porcine population act as mixing vessels for different avian influenza subtypes, that provide a suitable environment for reassortment and for creation of new viruses which may adapt to mammalian hosts [7,10]

Summary

Introduction

The low pathogenic avian influenza viruses of H9N2 subtype have become worldwide enzootic in the poultry population since its first detection in turkeys during 1966 [1,2,3] causes asymptomatic or mild disease in domestic poultry, which usually goes unnoticed. The H9N2 subtype virus is an extraordinary member of the influenza A group of viruses because it has a wide range of hosts including chickens, turkeys, ducks, pigs and even humans [6,7]. Quail and pigeon are considered as important reservoirs for the H9N2 viruses, as shown in China that they are serving as a linkage between waterfowl and terrestrial avian species [9]. Both quail and porcine population act as mixing vessels for different avian influenza subtypes, that provide a suitable environment for reassortment and for creation of new viruses which may adapt to mammalian hosts [7,10]

Methods

Results

Discussion

Conclusion