Abstract
BackgroundCampylobacter jejuni is commonly found in the gastrointestinal tract of many food-animals including sheep without causing visible clinical symptoms of disease. However, C. jejuni has been implicated in ovine abortion cases worldwide. Specifically, in the USA, the C. jejuni sheep abortion (SA) clone has been increasingly associated with sheep abortion. In vivo studies in sheep (the natural host) are needed to better characterize the virulence potential and pathogenesis of this clone.ResultsPregnant ewes intravenously (IV) or orally inoculated with ovine or bovine abortion-associated C. jejuni SA clones exhibited partial or complete uterine prolapse with retained placenta, and abortion or stillbirth, whereas delivery of healthy lambs occurred in pregnant ewes inoculated with C. jejuni 81–176 or in the uninfected group. In sheep inoculated with the SA clone, histopathological lesions including suppurative necrotizing placentitis and/or endometritis coincided with: 1) increased apoptotic death of trophoblasts, 2) increased expression of the host genes (e.g. genes encoding interleukin IL-6 and IL-15) related to cellular necrosis and pro-inflammatory responses in uterus, and 3) decreased expression of the genes encoding GATA binding protein 6, chordin, and insulin-like 3 (INSL3) that account for embryonic development in uterus. Immunohistochemistry revealed localization of bacterial antigens in trophoblasts lining the chorioallantoic membrane of ewes inoculated with the C. jejuni SA clone.ConclusionsThe results showed that C. jejuni SA clones are capable of causing abortion or stillbirth in experimentally infected sheep. Furthermore, down- or up-regulation of specific genes in the uterus of infected pregnant ewes might implicate host genes in facilitating the disease progression. Since the C. jejuni SA strains share genotypic similarities with clones that have been isolated from human clinical cases of gastroenteritis, these strains might represent a potential public health risk.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-014-0274-8) contains supplementary material, which is available to authorized users.
Highlights
Campylobacter jejuni is commonly found in the gastrointestinal tract of many food-animals including sheep without causing visible clinical symptoms of disease
The results showed that C. jejuni sheep abortion (SA) clones are capable of causing abortion or stillbirth in experimentally infected sheep
The results suggested that bovine and ovine C. jejuni clone SA can induce abortion in pregnant ewes by causing necrotizing suppurative placentitis and endometritis, which was supported by increased expressions of host genes related to cellular necrosis and suppurative inflammation
Summary
Campylobacter jejuni is commonly found in the gastrointestinal tract of many food-animals including sheep without causing visible clinical symptoms of disease. C. jejuni is commonly found in the intestinal tract of many food-producing animals, such as poultry, cattle, and sheep [1] In these hosts, C. jejuni generally persists without causing visible clinical clone SA has been detected in abortion cases in cows and goats [7]. In a recent study, PFGE analysis of C. jejuni SA isolates revealed a high similarity to human gastroenteritis-associated C. jejuni isolates [7]. This suggested a potential relevance of these ovine abortion isolates to human health. There is a critical need for understanding the pathogenesis of C. jejuni induced abortion
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