Abstract:
Background: Campylobacter 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.
Results: Pregnant 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.
Conclusions: The 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.
