Chlamydia pecorum Ovine Abortion: Associations between Maternal Infection and Perinatal Mortality.

Cheryl Jenkins,Justine Mcnally,Ronald Coilparampil,Pedro Pinczowski,Emily Onizawa,Thomas Westermann,Martina Jelocnik,Daniel Bogema

doi:10.3390/pathogens10111367

Abstract

Chlamydia pecorum 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 C. pecorum is a known cause of ovine abortion, clinical cases have only recently been described in detail. Here, the prevalence and sequence types (STs) of C. pecorum 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 C. pecorum 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 C. pecorum isolated from one abortion case revealed that the C. pecorum plasmid (pCpec) contained a unique deletion in coding sequence 1 (CDS1) that was also present in C. pecorum ST23 shed from the ewes. A further unique deletion was noted in a polymorphic membrane protein gene (pmpG) of the C. pecorum 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 C. pecorum-associated perinatal mortality, provides the first genomic data from an abortigenic C. pecorum strain, and raises questions about possible links between unique genetic features of this strain and C. pecorum abortion.

Highlights

Chlamydia pecorum is a globally distributed pathogen infecting a broad range of livestock and wildlife species [1,2,3]
This study describes infection parameters in a sheep flock experiencing C. pecorumassociated abortions
High Chlamydia antibody titres in ewes were strongly associated with perinatal mortality, while chlamydial shedding, as measured by quantitative PCR (qPCR), was not

Summary

Introduction

Chlamydia pecorum is a globally distributed pathogen infecting a broad range of livestock and wildlife species [1,2,3]. Infection with C. pecorum can be subclinical or manifest as a range of clinical syndromes including polyarthritis, keratoconjunctivitis, pneumonia, enteritis, and encephalomyelitis, as well as reproductive losses through infertility and abortion [6]. In livestock hosts, these syndromes impose a substantial burden on production with sheep, cattle, goats and pigs all susceptible to C. pecorum infection. Infections that are clinically inapparent have the potential to impact production, with one study demonstrating a 48% reduction in the growth rate of calves [7]. Studies conducted in Europe have demonstrated similar rates of infection in clinically healthy sheep flocks of between

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