Zhang Yu, Chen Yang, Gu Tiantian, Xu Qi, Zhu Guoqiang, Chen Guohong
Joint International Research Laboratory of Agriculture & Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou, China.
College of Veterinary Medicine, Yangzhou University, Yangzhou, China.
PeerJ. 2019 Jan 25;7:e6359. doi: 10.7717/peerj.6359. eCollection 2019.
Persistent colonization of the avian reproductive tract by serovar Enteritidis (SE) negatively affects egg production and contaminates the egg. The immune function of the ovary and oviduct is essential for protection from infection and for the production of wholesome eggs. However, the immune response of laying ducks during SE infection is not well-understood. In this study, ducks () were infected with SE and were systematically monitored for fecal shedding during a 13-week period. We also assessed bacterial distribution in the reproductive tract and classified infected ducks as resistant or susceptible based on the presence of tissue lesions and on SE isolation from fecal samples. We found that infected animals had persistent, but intermittent, bacterial shedding that resulted in the induction of carrier ducks. Laying rate and egg quality were also decreased after SE infection ( < 0.05). SE readily colonized the stroma, small follicle, isthmus, and vagina in the reproductive tracts of susceptible ducks. Immunoglobulin (IgA, IgG, IgM) levels were higher in susceptible ducks compared with resistant birds ( < 0.05); T-lymphocyte subpopulations (CD3, CD4, CD8) displayed the opposite trend. qRT-PCR analysis was used to examine expression profiles of immune response genes in the reproductive tract of infected ducks. The analysis revealed that immune genes, including toll-like receptors (TLR2, TLR4-5, TLR15, TLR21), NOD-like receptors (NOD1, NLRX1, NLRP12), avian β-defensins (AvβD4-5, AvβD7, AvβD12), cytokines (IL-6, IL-1β, IFN-γ), and MyD88 were markedly upregulated in the reproductive tracts of SE-infected ducks (all < 0.05); TLR3, TLR7, NLRC3, NLRC5, and TNF-α were significantly downregulated. These results revealed that SE infection promoted lower egg production and quality, and altered the expression of TLRs, NLRs, AvβDs, and cytokine family genes. These findings provide a basis for further investigation of the physiological and immune mechanisms of SE infection in laying ducks.
肠炎血清型（SE）在禽类生殖道中的持续定植会对产蛋产生负面影响，并污染禽蛋。卵巢和输卵管的免疫功能对于预防感染和生产健康禽蛋至关重要。然而，关于产蛋鸭在感染SE期间的免疫反应，目前尚不清楚。在本研究中，用SE感染鸭（品种未提及），并在13周内系统监测粪便排菌情况。我们还评估了生殖道中的细菌分布，并根据组织病变情况和粪便样本中SE的分离情况，将感染鸭分为抗性或易感型。我们发现，感染动物有持续但间歇性的细菌排菌现象，导致出现带菌鸭。SE感染后，产蛋率和蛋品质也有所下降（P<0.05）。SE很容易在易感鸭的生殖道基质、小卵泡、峡部和阴道中定植。与抗性鸭相比，易感鸭的免疫球蛋白（IgA、IgG、IgM）水平更高（P<0.05）；T淋巴细胞亚群（CD3、CD4、CD8）则呈现相反趋势。采用qRT-PCR分析检测感染鸭生殖道中免疫反应基因的表达谱。分析显示，包括Toll样受体（TLR2、TLR4-5、TLR15、TLR21）、NOD样受体（NOD1、NLRX1、NLRP12）、禽β-防御素（AvβD4-5、AvβD7、AvβD12）、细胞因子（IL-6、IL-1β、IFN-γ）和MyD88在内的免疫基因在SE感染鸭的生殖道中显著上调（均P<0.05）；TLR3、TLR7、NLRC3、NLRC5和TNF-α显著下调。这些结果表明，SE感染会导致产蛋量和蛋品质下降，并改变TLR、NLR、AvβD和细胞因子家族基因的表达。这些发现为进一步研究产蛋鸭SE感染的生理和免疫机制提供了依据。
