Ducks induce rapid and robust antibody responses than chickens at early time after intravenous infection with H9N2 avian influenza virus

Jianmei Yang,Qinfang Liu,Hongrui Cui,Xuesong Li,Zejun Li,Hongjun Chen,Dawei Yan,Wenjun Ma,Qiaoyang Teng,Binbin Wang

doi:10.1186/s12985-019-1150-8

Abstract

BackgroundCompared with chickens, ducks are normally resistant to avian influenza virus without clinical signs while they habor almost all subtypes of influenza A viruses. To date, however the mechanism for duck anti-influenza has not been completely understood. The H9N2 avian influenza virus (AIV) is the most prevalent subtype of influenza A virus that infects chickens and ducks in China. However, H9N2 AIV replication and the host immune response in these domestic birds has not been systematically investigated.MethodsIn the present study, we compared the kinetics and magnitudes of antibody responses in chickens and ducks after infection with H9N2 AIV by the intranasal route or intravenous route. Furthermore, we determined the viral replication and distribution in chickens and ducks after infection with H9N2 AIV by the intravenous route.ResultsOur results revealed that the antibody response was rapid and robust in ducks than in chickens at early time (2-3dpi) after intravenous infection with H9N2 AIVs, while delayed and lower antibody detected in ducks than in chickens after intranasal infection with H9N2 AIVs. The virus was detected in multiple organs tissues in chickens but not in ducks infected by the intravenous route.ConclusionsOur results provide the evidence that humoral immune response could play a critical role in duck resistance for influenza, which expands our knowledge on duck anti-influenza characteristics.

Highlights

Compared with chickens, ducks are normally resistant to avian influenza virus without clinical signs while they habor almost all subtypes of influenza A viruses
Antibody response in birds intranasally infected with the H9N2 virus Following intranasal infection with the H9N2 virus, three out of five chickens seroconverted at 4 dpi to a positive hemagglutination inhibition (HI) titer (HI > log24) and all chickens (5/5) seroconverted at 6 dpi with a higher HI titer and inhibition according to the results of the blocking Enzyme linked immunosorbent assay (ELISA) (PI > 25%) (Fig. 1)
These results reveal that ducks display delayed seroconversion compared to chickens when they are intranasally infected with the H9N2 virus

Summary

Introduction

Ducks are normally resistant to avian influenza virus without clinical signs while they habor almost all subtypes of influenza A viruses. The H9N2 avian influenza virus (AIV) is the most prevalent subtype of influenza A virus that infects chickens and ducks in China. Ducks have been found to mount more active and robust cellular immune responses compared to chickens exposed to H9N2 AIV by the intranasal route [20]. Following infection with HPAIVs, ducks are able to initiate a faster but lower inflammatory cytokine response followed by the activation of major pattern recognition receptors (i.e., TLR7, RIG-I, and MDA-5) and a persistent cellular response, whereas chickens generate excessive but delayed inflammatory cytokine responses followed by inadequate cellular immune responses, which may result in a higher pathogenicity of the virus in chickens [16]. The mechanism for duck anti-influenza is still in dark and has been shown complicated as different results were observed due to different virulent virus strain and viral exposure routes

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