Ebers Katie L, Zhang C Yan, Zhang M Zhenyu, Bailey R Hartford, Zhang Shuping
Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, PO Box 97813, Pearl, MS 39288, USA.
BMC Microbiol. 2009 Jul 30;9:153. doi: 10.1186/1471-2180-9-153.
Salmonella enterica serovar Enteritidis (SE) colonizes the ovary and oviduct of chickens without causing overt clinical signs which can lead to SE-contamination of the content and membrane of shell-eggs as well as hatchery eggs. The organism utilizes the Salmonella Pathogenicity Island-2 encoded type III secretion system (T3SS-2) to promote persistence in the oviduct of laying hens. In this study, reverse transcriptase-polymerase chain reaction (RT-PCR) was carried out to determine the expression profiles of 14 known avian beta defensins (AvBDs) in primary chicken oviduct epithelial cells (COEC) before and after infections with a wild type SE strain and T3SS mutant SE strains carrying an inactivated sipA or pipB gene.
Based on the expression levels in uninfected COEC, AvBDs can be loosely grouped into three categories with AvBD4-5 and AvBD9-12 being constitutively expressed at high levels; AvBD1, AvBD3, and AvBD13-14 at moderate levels; and AvBD2 and AvBD6-8 at minimal levels. Infection with the wild type SE strain temporarily repressed certain highly expressed AvBDs and induced the expression of minimally expressed AvBDs. The pipB mutant, compared to the wild type strain, had reduced suppressive effect on the expression of highly expressed AvBDs. Moreover, the pipB mutant elicited significantly higher levels of the minimally expressed AvBDs than the wild type SE or the sipA mutant did.
Chicken oviduct epithelial cells express most of the known AvBD genes in response to SE infection. PipB, a T3SS-2 effector protein, plays a role in dampening the beta-defensin arm of innate immunity during SE invasion of chicken oviduct epithelium.
肠炎沙门氏菌肠炎亚种（SE）定殖于鸡的卵巢和输卵管，不引起明显临床症状，这可能导致蛋鸡蛋壳内容物和膜以及孵化场鸡蛋受到SE污染。该菌利用沙门氏菌致病岛2编码的III型分泌系统（T3SS-2）来促进在蛋鸡输卵管中的持续存在。在本研究中，进行了逆转录聚合酶链反应（RT-PCR），以确定野生型SE菌株以及携带失活sipA或pipB基因的T3SS突变SE菌株感染前后，原代鸡输卵管上皮细胞（COEC）中14种已知禽β-防御素（AvBDs）的表达谱。
根据未感染COEC中的表达水平，AvBDs可大致分为三类，AvBD4-5和AvBD9-12持续高水平表达；AvBD1、AvBD3和AvBD13-14中等水平表达；AvBD2和AvBD6-8最低水平表达。野生型SE菌株感染暂时抑制了某些高表达的AvBDs，并诱导了低表达AvBDs的表达。与野生型菌株相比，pipB突变体对高表达AvBDs表达的抑制作用降低。此外，pipB突变体诱导的低表达AvBDs水平显著高于野生型SE或sipA突变体。
鸡输卵管上皮细胞在受到SE感染时会表达大多数已知的AvBD基因。PipB是一种T3SS-2效应蛋白，在SE侵袭鸡输卵管上皮过程中，对先天免疫的β-防御素分支起到抑制作用。
