Genetic Characteristics and Pathogenicity Analysis in Chickens and Mice of Three H9N2 Avian Influenza Viruses.

Yafen Song,Bing Zhang,Taozhen Jiang,Yong Zhang,Min Zhang,Jingwen Wang,Chenghuai Yang,Ling Chen,Ying Jiang

doi:10.3390/v11121127

Abstract

H9N2 avian influenza is a remarkable disease that has circulated in domestic poultry in large regions of China and posed a serious threat to the poultry industry. The H9N2 virus can not only infect mammals directly, but also provide gene segments to generate novel, but lethal human reassortants. Therefore, it is important to study the evolution, pathogenicity, and transmission of the H9N2 virus. In this study, three H9N2 viruses isolated from chickens in different layer farms were identified. Phylogenetic analysis revealed that these H9N2 viruses were all multiple genotype reassortants, with genes originating from Y280-like, F/98-like, and G1-like viruses. Animal studies indicated that the AV1535 and AV1548 viruses replicated efficiently in the lungs, tracheas, spleens, kidneys, and brains of chickens; the viruses shed for at least 11 days post-inoculation (DPI) and were transmitted efficiently among contact chickens. The AV1534 virus replicated poorly in chickens, shed for 7 DPI, and were not transmitted efficiently among contact chickens. The AV1534 virus replicated well in mice lungs and caused about 2% weight loss. The AV1535 and AV1548 viruses were not able to replicate in the lungs of mice. Our results indicate that we should pay attention to H9N2 avian influenza virus surveillance in poultry and changes in the pathogenicity of them to mammals.

Highlights

H9N2 avian influenza virus (AIV), known as one of the predominant subtypes devastating the poultry industry, has circulated widely in the poultry population and caused huge economic losses.H9N2 avian influenza has been reported in all continents since the virus was first isolated from turkeys in North America in 1966 [1,2]
Phylogenetic analysis of the HA genes revealed that AV1534, AV1535, and AV1548 viruses all fell into the Y280-like lineage (Figure 1A)
H9N2 virus is more likely to infect and transmit asymptomatically among birds, which could increase the chance of gene reassortment with other AIVs during co-infection

Summary

Introduction

H9N2 avian influenza virus (AIV), known as one of the predominant subtypes devastating the poultry industry, has circulated widely in the poultry population and caused huge economic losses. H9N2 avian influenza has been reported in all continents since the virus was first isolated from turkeys in North America in 1966 [1,2]. In Asia, H9N2 avian influenza viruses (AIVs) were only detected in apparently healthy ducks before the 1990s [3]. H9N2 viruses could be found in chickens in many Asian countries [4,5]. In China, the first outbreak of the H9N2 avian influenza was in chickens of Guangdong Province, from November 1992 to May 1994, and the virus was first identified in 1994 [4].

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Results

Conclusion