Screening of linear B-cell epitopes and its proinflammatory activities of Haemophilus parasuis outer membrane protein P2

Frontiers in Cellular and Infection Microbiology

Cellular and Infection Microbiology

Chongbo Xu¹  Zhengzhong Xiao¹  Jianqiang Huang¹  Jingbo Wu²  Honghui Hu³  Wenjin Nan³  Guoliang Peng³ 

[1]Henry Fok College of Yingdong Biology and Agricultural, Shaoguan University, Shaoguan, China

[2]North Guangdong Collaborative Innovation and Development Center of Pig Farming and Disease Control, Shaoguan University, Shaoguan, China

[3]Henry Fok College of Yingdong Biology and Agricultural, Shaoguan University, Shaoguan, China

[4]North Guangdong Collaborative Innovation and Development Center of Pig Farming and Disease Control, Shaoguan University, Shaoguan, China

[5]North Guangdong Pig Breeding Waste Reduction Engineering Technology Center, Shaoguan University, Shaoguan, China

[6]Henry Fok College of Yingdong Biology and Agricultural, Shaoguan University, Shaoguan, China

[7]North Guangdong Pig Breeding Waste Reduction Engineering Technology Center, Shaoguan University, Shaoguan, China

关键词: Haemophilus parasuis;    linear B-cell epitopes;    OmpP2 protein;    proinflammatory cytokines;    genotype;   

DOI  :  10.3389/fcimb.2023.1192651

 received in 2023-03-23, accepted in 2023-04-11,  发布年份 2023

来源: Frontiers

【 摘 要 】

Haemophilus parasuis is a commensal organism of the upper respiratory tract of pigs, but virulent strains can cause Glässer’s disease, resulting in significant economic losses to the swine industry. OmpP2 is an outer membrane protein of this organism that shows considerable heterogeneity between virulent and non-virulent strains, with classification into genotypes I and II. It also acts as a dominant antigen and is involved in the inflammatory response. In this study, 32 monoclonal antibodies (mAbs) against recombinant OmpP2 (rOmpP2) of different genotypes were tested for reactivity to a panel of OmpP2 peptides. Nine linear B cell epitopes were screened, including five common genotype epitopes (Pt1a, Pt7/Pt7a, Pt9a, Pt17, and Pt19/Pt19a) and two groups of genotype-specific epitopes (Pt5 and Pt5-II, Pt11/Pt11a, and Pt11a-II). In addition, we used positive sera from mice and pigs to screen for five linear B-cell epitopes (Pt4, Pt14, Pt15, Pt21, and Pt22). After porcine alveolar macrophages (PAMs) were stimulated with overlapping OmpP2 peptides, we found that the epitope peptides Pt1 and Pt9, and the loop peptide Pt20 which was adjacent epitopes could all significantly upregulated the mRNA expression levels of IL-1α, IL-1β, IL-6, IL-8, and TNF-α. Additionally, we identified epitope peptides Pt7, Pt11/Pt11a, Pt17, Pt19, and Pt21 and loop peptides Pt13 and Pt18 which adjacent epitopes could also upregulate the mRNA expression levels of most proinflammatory cytokines. This suggested that these peptides may be the virulence-related sites of the OmpP2 protein, with proinflammatory activity. Further study revealed differences in the mRNA expression levels of proinflammatory cytokines, including IL-1β and IL-6, between genotype-specific epitopes, which may be responsible for pathogenic differences between different genotype strains. Here, we profiled a linear B-cell epitope map of the OmpP2 protein and preliminarily analyzed the proinflammatory activities and effects of these epitopes on bacterial virulence, providing a reliable theoretical basis for establishing a method to distinguish strain pathogenicity and to screen candidate peptides for subunit vaccines.

【 授权许可】

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Copyright © 2023 Wu, Nan, Peng, Hu, Xu, Huang and Xiao