Ovine Abortion: Associations between Maternal Infection and Perinatal Mortality.

is a common gastrointestinal inhabitant of livestock but infections can manifest in a broad array of clinical presentations and in a range of host species. While is a known cause of ovine abortion, clinical cases have only recently been described in detail. Here, the prevalence and sequence types (STs) of in ewes from a property experiencing high levels of perinatal mortality (PNM) in New South Wales (NSW), Australia, were investigated using serological and molecular methods. Ewes that were PNM+ were statistically more likely to test seropositive compared to PNM- ewes and displayed higher antibody titres; however, an increase in chlamydial shedding from either the rectum, vagina or conjunctiva of PNM+ ewes was not observed. Multilocus sequence typing (MLST) indicated that ST23 was the major ST shed by ewes in the flock, was the only ST identified from the vaginal site, and was the same ST detected within aborted foetal tissues. Whole genome sequencing of isolated from one abortion case revealed that the plasmid (pCpec) contained a unique deletion in coding sequence 1 (CDS1) that was also present in ST23 shed from the ewes. A further unique deletion was noted in a polymorphic membrane protein gene (pmpG) of the chromosome, which warrants further investigation given the role of PmpG in host cell adherence and tissue tropism.This study describes novel infection parameters in a sheep flock experiencing -associated perinatal mortality, provides the first genomic data from an abortigenic strain, and raises questions about possible links between unique genetic features of this strain and abortion.