title: Roles of the surface layer proteins of Campylobacter fetus subsp. fetus in ovine abortion.
abstract: The role of the surface (S)-layer proteins of Campylobacter fetus subsp. fetus has been investigated using an ovine model of abortion. Wild-type strain 23D induced abortion in up to 90% of pregnant ewes challenged subcutaneously. Isolates recovered from both dams and fetuses expressed S-layer proteins with variable molecular masses. The spontaneous S-layer-negative variant, strain 23B, neither colonized nor caused abortions in pregnant ewes. A series of isogenic sapA and recA mutants, derived from 23D, also were investigated in this model. A mutant (501 [sapA recA(+)]) caused abortion in one of five challenged animals and was recovered from the placenta of a second animal. Another mutant (502 [sapA recA]) with no S-layer protein expression caused no colonization or abortions in challenged animals but caused abortion when administered intraplacentally. Mutants 600(2) and 600(4), both recA, had fixed expression of 97- and 127-kDa S-layer proteins, respectively. Two of the six animals challenged with mutant 600(4) were colonized, but there were no abortions. As expected, all five strains recovered expressed a 127-kDa S-layer protein. In contrast, mutant 600(2) was recovered from the placentas of all five challenged animals and caused abortion in two. Unexpectedly, one of the 16 isolates expressed a 127-kDa rather than a 97-kDa S-layer protein. Thus, these studies indicate that S-layer proteins appear essential for colonization and/or translocation to the placenta but are not required to mediate fetal injury and that S-layer variation may occur in a recA strain.
authors.affiliation: Department of Farm Animal, Royal Veterinary College, Hertfordshire, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Grogono-Thomas
authors.forename: J
authors.initials: J
authors.lastname: Dworkin
authors.forename: M J
authors.initials: MJ
authors.lastname: Blaser
authors.forename: D G
authors.initials: DG
authors.lastname: Newell
mesh_terms: D000034:Abortion, Veterinary / Q000209:etiology*; D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis / Q000502:physiology*; D002168:Campylobacter fetus / Q000737:chemistry / Q000472:pathogenicity*; D005260:Female; D008562:Membrane Glycoproteins; D008970:Molecular Weight; D011247:Pregnancy; D011817:Rabbits; D011938:Rec A Recombinases / Q000032:analysis; D012756:Sheep
chemical_list: D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; C055764:S-layer proteins; D011938:Rec A Recombinases