Institute for Microbiology, University of Veterinary Medicine Hannover , Hannover, Germany.
Institute for Pathology, University of Veterinary Medicine Hannover , Hannover, Germany.
Virulence. 2021 Dec;12(1):84-95. doi: 10.1080/21505594.2020.1858604.
and are major pathogens in pigs, which are frequently isolated from co-infections in the respiratory tract and contribute to the porcine respiratory disease complex (PRDC). Despite the high impact of co-infections on respiratory diseases of swine (and other hosts), very little is known about pathogen-pathogen-host interactions and the mechanisms of pathogenesis. In the present study, we established a porcine precision-cut lung slice (PCLS) model to analyze the effects of infection on adherence, colonization, and cytotoxic effects of . We hypothesized that induction of ciliostasis by a clinical isolate of may promote subsequent infection with a virulent serotype 2 strain. To investigate this theory, we monitored the ciliary activity by light microscopy, measured the release of lactate dehydrogenase, and calculated the number of PCLS-associated bacteria. To study the role of the pore-forming toxin suilysin (SLY) in -induced cytotoxicity, we included a SLY-negative isogenic mutant and the complemented mutant strain. Furthermore, we analyzed infected PCLS by histopathology, immunofluorescence microscopy, and field emission scanning electron microscopy. Our results showed that pre-infection with promoted adherence, colonization, and, as a consequence of the increased colonization, the cytotoxic effects of , probably by reduction of the ciliary activity. Moreover, cytotoxicity induced by is strictly dependent on the presence of SLY. Though the underlying molecular mechanisms remain to be fully clarified, our results clearly support the hypothesis that paves the way for infection.
和 是猪的主要病原体，它们经常从呼吸道的合并感染中分离出来，并导致猪呼吸道疾病复合症（PRDC）。尽管合并感染对猪（和其他宿主）的呼吸道疾病有很大的影响，但对病原体-病原体-宿主相互作用和发病机制知之甚少。在本研究中，我们建立了猪精密肺切片（PCLS）模型，以分析 感染对 粘附、定植和细胞毒性的影响。我们假设临床分离株引起的纤毛静止可能促进随后感染毒力更强的 2 型血清型。为了验证这一理论，我们通过相差显微镜监测纤毛活动，测量乳酸脱氢酶的释放，并计算与 PCLS 相关的细菌数量。为了研究孔形成毒素溶血素（SLY）在 诱导的细胞毒性中的作用，我们包括了一个 SLY 阴性的同源突变体和互补突变体菌株。此外，我们通过组织病理学、免疫荧光显微镜和场发射扫描电子显微镜分析了感染的 PCLS。我们的结果表明，预先感染 促进了 粘附、定植和随后的细胞毒性作用，这可能是由于纤毛活动减少导致的定植增加。此外， 诱导的细胞毒性严格依赖于 SLY 的存在。虽然潜在的分子机制仍有待充分阐明，但我们的结果清楚地支持这样一种假设，即 为 感染铺平了道路。
