Ghent University, Faculty of Veterinary Medicine, Department of Pathology, Bacteriology and Avian Diseases, Salisburylaan 133, 9820 Merelbeke, Belgium.
Comp Immunol Microbiol Infect Dis. 2013 Sep;36(5):465-71. doi: 10.1016/j.cimid.2013.03.007. Epub 2013 May 10.
Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella Typhimurium is the serovar most frequently isolated from persistently infected slaughter pigs in Europe. Salmonella Typhimurium pathogenesis is host species specific. In addition, differences in in vitro behaviour of Salmonella Typhimurium strains have also been described, which may be reflected by a different course of infection within a host species. We compared the course of a Salmonella Typhimurium infection in pigs, using two Salmonella Typhimurium strains that were able to interfere with MHC II expression on porcine macrophages to a different extent in vitro. After experimental inoculation, blood and faecal samples from all pigs were collected at regular time points. At 40 days post inoculation (pi), animals were euthanized and tissue samples were bacteriologically analysed. The proportion of serologically positive piglets at 33 days pi was significantly higher in pigs that were inoculated with the strain that did not downregulate MHC II expression in vitro. Furthermore, this strain was less frequently shed and isolated in lower numbers from tonsils and ileocaecal lymph nodes than the strain that was able to markedly downregulate MHC II expression in vitro. We thus found that the delayed onset of seroconversion after oral inoculation of piglets with a particular Salmonella Typhimurium strain coincided with higher faecal shedding and increased persistence. Strain specific differences in Salmonella pathogenesis might thus have repercussions on the serological detection of Salmonella Typhimurium infections in pigs.
食源性沙门氏菌病是全球最重要的细菌性人畜共患病之一。在欧洲，从持续感染的屠宰猪中分离出的血清型沙门氏菌血清型鼠伤寒沙门氏菌最为常见。鼠伤寒沙门氏菌的发病机制具有宿主种特异性。此外，还描述了鼠伤寒沙门氏菌株在体外行为的差异，这可能反映了在宿主种内感染的不同过程。我们比较了两种鼠伤寒沙门氏菌菌株在猪中的感染过程，这两种菌株在体外能够以不同的程度干扰猪巨噬细胞 MHC II 的表达。实验接种后，定期从所有猪采集血液和粪便样本。在接种后 40 天（pi），对动物进行安乐死，并对组织样本进行细菌学分析。在 33 天 pi 时血清学阳性仔猪的比例在接种体外不下调 MHC II 表达的菌株的猪中明显更高。此外，与能够显著下调 MHC II 体外表达的菌株相比，该菌株在扁桃体和回肠淋巴结中的脱落和分离频率更低，数量也更少。因此，我们发现仔猪口服接种特定鼠伤寒沙门氏菌菌株后血清转化的延迟发生与粪便脱落增加和持续时间延长相一致。沙门氏菌发病机制的菌株特异性差异可能会对猪沙门氏菌感染的血清学检测产生影响。
