Efficacy of an inactivated bivalent vaccine against the prevalent strains of Newcastle disease and H9N2 avian influenza

Jing Zhao,Guozhong Zhang,Hongjun Xu,Huiming Yang,Zengbin Ma

doi:10.1186/s12985-017-0723-7

Jing Zhao, Guozhong Zhang + Show 3 more

Open Access

https://doi.org/10.1186/s12985-017-0723-7

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Abstract

BackgroundNewcastle disease (ND) and avian influenza subtype H9N2 (H9N2 AI) are two of the most important diseases of poultry, causing severe economic losses in the global poultry industry. Vaccination is an effective way to prevent and control the spread of ND virus (NDV) and H9N2 AI virus (AIV), but the antigenic differences between the current circulating strains and the vaccine strains might account for recent ND and H9N2 AI outbreaks in vaccinated poultry flocks.MethodsWe developed an inactivated bivalent H9N2 and NDV vaccine based on the current prevalent strains of H9N2 AIV and NDV in China and evaluated its efficacy in chickens in this study.ResultsThe results indicated that the inactivated bivalent vaccine could induce a fast antibody response in vaccinated chickens. The hemagglutination inhibition (HI) titer in the sera increased rapidly, and the highest HI titer was observed at 4 weeks post-vaccination (wpv) with a mean titre of 8.6 log2 for NDV and 9.5 log2 for H9N2. Up until 15 wpv, HI titers were still detectable at a high level of over 6 log2. The immunized chickens showed no signs of disease after challenge at 3 wpv with the prevalent strains of NDV and H9N2 AIV isolated in 2012–2014. Moreover, viral shedding was completely inhibited in vaccinated chickens after challenge with H9N2 AIV and inhibited by at least 90% with NDV compared to the controls at 5dpc.ConclusionsOur findings suggest that the inactivated NDV and H9N2 vaccine induces a fast and strong antibody response in vaccinated chickens and is efficacious in poultry against NDVs and H9N2 AIVs.

Highlights

Newcastle disease (ND) and avian influenza subtype H9N2 (H9N2 AI) are two of the most important diseases of poultry, causing severe economic losses in the global poultry industry
Our findings suggest that the inactivated ND virus (NDV) and H9N2 vaccine induces a fast and strong antibody response in vaccinated chickens and is efficacious in poultry against NDVs and H9N2 AI virus (AIV)
We developed an inactivated H9N2 and NDV vaccine based on a H9N2 A/chicken/Hebei/G/2012 (G) virus and a ND Chicken/Shandong/aSG10/2010 attenuated virus that are closely related to the current endemic strains of H9N2 and ND virus in China and evaluated its efficacy in chickens

Summary

Introduction

Newcastle disease (ND) and avian influenza subtype H9N2 (H9N2 AI) are two of the most important diseases of poultry, causing severe economic losses in the global poultry industry. Newcastle disease virus (NDV) and avian influenza virus (AIV) are two of the most important pathogens in poultry worldwide [1]. Newcastle disease (ND) is usually caused by virulent NDV, which can result in 100% mortality in many species of birds [2]. The H9N2 low pathogenic avian influenza viruses have been circulating worldwide in multiple avian species, resulting in great economic losses owing to reduced egg production or increased mortality associated with coinfection with other pathogens [3,4,5,6]. We genotypically characterized the NDV isolates recovered from chickens between 2005 and 2012 to establish the nature of the circulating

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