Ni Ligang, Song Chengyi, Wu Xinsheng, Zhao Xuting, Wang Xiaoyan, Li Bichun, Gan Yuan
College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, China.
Department of Animal Science and Technology, Jiangsu Agri-animal Husbandry Vocational College, Taizhou, Jiangsu, China.
PeerJ. 2019 Oct 21;7:e7900. doi: 10.7717/peerj.7900. eCollection 2019.
(Mhp) is the main pathogen causing respiratory disease in the swine industry. Mhp infection rates differ across pig breeds, with Chinese native pig breeds that exhibit high fecundity (e.g., Jiangquhai, Meishan, Erhualian) more sensitive than Duroc, Landrace, and other imported pig breeds. However, the genetic basis of the immune response to Mhp infection in different pig breeds is largely unknown.
The aims of this study were to determine the relative Mhp susceptibility of the Chinese native Jiangquhai breed compared to the Duroc breed, and identify molecular mechanisms of differentially expressed genes (DEGs) using an RNA-sequencing (RNA-seq) approach.
Jiangquhai and Duroc pigs were artificially infected with the same Mhp dose. The entire experiment lasted 28 days. Daily weight gain, Mhp-specific antibody levels, and lung lesion scores were measured to evaluate the Mhp infection susceptibility of different breeds. Experimental pigs were slaughtered on the 28th day. Lung tissues were collected for total RNA extraction. RNA-seq was performed to identify DEGs, which were enriched by gene ontology (GO) and the Kyoto Encyclopedia annotation of Genes and Genomes (KEGG) databases. DEGs were validated with real-time quantitative polymerase chain reaction (RT-qPCR).
Infection with the same Mhp dose produced a more serious condition in Jiangquhai pigs than in Duroc pigs. Jiangquhai pigs showed poorer growth, higher Mhp antibody levels, and more serious lung lesions compared with Duroc pigs. RNA-seq identified 2,250 and 3,526 DEGs in lung tissue from Jiangquhai and Duroc pigs, respectively. The two breeds shared 1,669 DEGs, which were involved in immune-relevant pathways including cytokine-cytokine receptor interaction, PI3K-Akt signaling pathway, and chemokine signaling pathway. Compared to Jiangquhai pigs, more chemokines, interferon response factors, and interleukins were specifically activated in Duroc pigs; , , and genes were significantly up-regulated, which may help Duroc pigs enhance immune response and reduce Mhp susceptibility.
This study demonstrated differential immune-related DEGs in lung tissue from the two breeds, and revealed an important role of genetics in the immune response to Mhp infection. The biological functions of these important DEGs should be further confirmed and maybe applied as molecular markers that improve pig health.
猪肺炎支原体（Mhp）是养猪业中引起呼吸道疾病的主要病原体。Mhp感染率因猪的品种而异，具有高繁殖力的中国本土猪品种（如姜曲海猪、梅山猪、二花脸猪）比杜洛克猪、长白猪和其他进口猪品种更易感。然而，不同猪品种对Mhp感染的免疫反应的遗传基础在很大程度上尚不清楚。
本研究的目的是确定中国本土姜曲海猪与杜洛克猪相比对Mhp的相对易感性，并使用RNA测序（RNA-seq）方法鉴定差异表达基因（DEG）的分子机制。
用相同剂量的Mhp人工感染姜曲海猪和杜洛克猪。整个实验持续28天。测量日增重、Mhp特异性抗体水平和肺病变评分，以评估不同品种对Mhp感染的易感性。在第28天宰杀实验猪。收集肺组织用于总RNA提取。进行RNA-seq以鉴定DEG，这些DEG通过基因本体论（GO）和京都基因与基因组百科全书（KEGG）数据库进行富集。用实时定量聚合酶链反应（RT-qPCR）验证DEG。
相同剂量的Mhp感染在姜曲海猪中产生的病情比在杜洛克猪中更严重。与杜洛克猪相比，姜曲海猪生长较差、Mhp抗体水平较高且肺病变更严重。RNA-seq在姜曲海猪和杜洛克猪的肺组织中分别鉴定出2250个和3526个DEG。两个品种共有1669个DEG，这些DEG参与免疫相关途径，包括细胞因子-细胞因子受体相互作用、PI3K-Akt信号通路和趋化因子信号通路。与姜曲海猪相比杜洛克猪中更多的趋化因子、干扰素反应因子和白细胞介素被特异性激活； 、 、 和 基因显著上调，这可能有助于杜洛克猪增强免疫反应并降低对Mhp的易感性。
本研究证明了两个品种肺组织中与免疫相关的DEG存在差异，并揭示了遗传在对Mhp感染的免疫反应中的重要作用。这些重要DEG的生物学功能应进一步得到证实，并可能用作改善猪健康的分子标记。
