Protective Efficacy of an Inactive Vaccine Based on the LY02 Isolate against Acute Haemophilus parasuis Infection in Piglets.

Xiao-Hua Li,Ai-Ling Dai,Guo-Zhen Zhao,Long-Xin Qiu,Xiao-Yan Yang,Wang-Wei Wu

doi:10.1155/2015/649878

Xiao-Hua Li, Ai-Ling Dai + Show 4 more

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https://doi.org/10.1155/2015/649878

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Abstract

Haemophilus parasuis can cause Glässer's disease characterized by fibrinous polyserositis, polyarthritis, and meningitis. The current prevention of Glässer's disease is mainly based on the inactive vaccines; however, the protective efficacy usually fails in heterogeneous or homologous challenges. Here, the predominant lineage of H. parasuis (LY02 strain) in Fujian province, China, characterized as serovar 5, was used to evaluate the protective immunity against acute H. parasuis infection in piglets after inactivation. Following challenging with H. parasuis, only mild lesions in the pigs immunized with the killed vaccine were observed, whereas the typical symptoms of Glässer's disease presented in the nonimmunized piglets. A strong IgG immune response was induced by the inactive vaccine. CD4+ and CD8+ T lymphocyte levels were increased, indicating the potent cellular immune responses were elicited. The significantly high levels of IL-2, IL-4, TGF-β, and IFN-γ in sera from pigs immunized with this killed vaccine suggested that the mixed Th1 and Th2 immune responses were induced, associated with the high protection against H. parasuis infection compared to the nonimmunized animals. This study indicated that the inactivated LY02 strain of H. parasuis could serve as a potential vaccine candidate to prevent the prevalence of H. parasuis in Fujian province, China.

Highlights

The Gram-negative and NAD-dependent Haemophilus parasuis is normally isolated from the upper respiratory tract of healthy swine [1, 2]
The bacteria is opportunistic pathogen that can lead to severe systemic infection characterized by fibrinous polyserositis, polyarthritis, and meningitis in piglets, known as Glasser’s disease [2, 3]
Several previous studies indicated that the killed vaccines could elicit efficient protective immunity against H. parasuis infection compared to any single antigen [5, 7, 8]

Summary

Introduction

The Gram-negative and NAD-dependent Haemophilus parasuis is normally isolated from the upper respiratory tract of healthy swine [1, 2]. The bacteria is opportunistic pathogen that can lead to severe systemic infection characterized by fibrinous polyserositis, polyarthritis, and meningitis in piglets, known as Glasser’s disease [2, 3]. Under the modern intensive production system, this disease, as important emergence, has produced significant mortality and morbidity in pig industry, resulting in severe economic losses worldwide [1, 2, 4]. For controlling Glasser’s disease, the primary alternative is considered using vaccination [5]. Several previous studies indicated that the killed vaccines could elicit efficient protective immunity against H. parasuis infection compared to any single antigen [5, 7, 8]

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