Phylogenetic and molecular analysis based on genes 16S-rRNA, OMPA and POMP to identify Chlamydia abortus infection occurrence at the milk samples of goats and sheep in west Azerbaijan of Iran

Background and Objectives: Enzootic abortion in sheep and goats, also called ovine enzootic abortion (OEA) or enzootic abortion of ewes (EAE), is caused by Chlamydia abortus. The disease has a major economic impact as it represents the most important cause of lamb loss in sheep in parts of Europe, North America and Africa. This serious and potentially life-threat- ening zoonosis can also affect pregnant women after contact with lambing ewes, leading to severe febrile illness in pregnancy and loss of the foetus. Materials and Methods: The present study was conducted to the Phylogenetic and Molecular Analysis based on Genes 16S-rRNA, OmpA and POMP of C. abortus in milk samples collected from sheep and goats in West Azerbaijan province, Iran. During 2018, a total number of 360 milk samples were collected from sheep (n = 180) and goats (n = 180) of different regions of the province. All milk samples were subjected to DNA extraction and examined by PCR. Results: Among 360 milk samples collected from sheep and goats, 31 (8.611%; 95% CI=6.13-11.96) were positive for Chlamydia spp. The helicase, 16S-rRNA and ompA genes were examined and resulted in 8, 31, 31 of positive samples re- spectively. The accession numbers have been deposited in GenBank (NCBI) (MT367602 and MT367603). Conclusion: Phylogenetic analysis based on the gene of helicase showed that most of the isolates shared similarity > 99.97%.

Enzootic abortion in sheep: a review

Enzootic abortion of ewes (EAE) is the most commonly diagnosed cause of abortion in sheep in the UK. This document will review disease background, how to reach a diagnosis of EAE, and recent developments in diagnostics and preventative approaches. It also explores the scope for progress and how that may be achieved. There is significant scope for more widespread screening and vaccination against EAE to yield benefits to animal health, human health, antibiotic stewardship, individual farm profitability and the UK sheep sector.

Distribution and Severity of Placental Lesions Caused by the Chlamydia abortus 1B Vaccine Strain in Vaccinated Ewes

Chlamydia abortus infects livestock species worldwide and is the cause of enzootic abortion of ewes (EAE). In Europe, control of the disease is achieved using a live vaccine based on C. abortus 1B strain. Although the vaccine has been useful for controlling disease outbreaks, abortion events due to the vaccine have been reported. Recently, placental pathology resulting from a vaccine type strain (vt) infection has been reported and shown to be similar to that resulting from a natural wild-type (wt) infection. The aim of this study was to extend these observations by comparing the distribution and severity of the lesions, the composition of the predominating cell infiltrate, the amount of bacteria present and the role of the blood supply in infection. A novel system for grading the histological and pathological features present was developed and the resulting multi-parameter data were statistically transformed for exploration and visualisation through a tailored principal component analysis (PCA) to evaluate the difference between them. The analysis provided no evidence of meaningful differences between vt and wt strains in terms of the measured pathological parameters. The study also contributes a novel methodology for analysing the progression of infection in the placenta for other abortifacient pathogens.

Enzootic abortion of ewes

This focus article has been prepared by Amanda Carson and Rudolf Reichel of the APHA Small Ruminant Species Expert Group and Maggie He, data analyst at the APHA Surveillance Intelligence Unit.

Application of quantitative real-time polymerase chain reaction for the diagnosis of toxoplasmosis and enzootic abortion of ewes

Toxoplasma gondii and Chlamydophila abortus are the 2 most common infectious causes of ovine abortion worldwide. These obligate intracellular pathogens are associated with severe placentitis leading to abortion or stillbirth in pregnant ewes, and resulting in significant economic losses. The objectives of the current study were the development, validation, and application of a duplex real-time polymerase chain reaction (PCR) assay capable of quantifying the burden of infection by T. gondii and C. abortus in material submitted for diagnostic purposes. The validation was carried out using samples from ewes experimentally infected with these organisms. Based on the numbers of genome copies detected, an arbitrary cutoff level was established to correlate with significant pathological changes sufficient to give rise to abortion. When the PCR assay was applied to samples from 66 Irish farms with naturally occurring outbreaks of ovine abortion, toxoplasmosis and enzootic abortion of ewes (EAE) accounted for 14% and 20% of the farms, respectively, while on 6% of the farms, there was evidence of dual infection. When standard diagnostic techniques including histopathological examination, serological analysis, chlamydial antigen detection, and bacteriological culture, were used on samples from the same farms, toxoplasmosis was diagnosed in 17% of farms, and EAE in 12%; dual infection was diagnosed on 3% of the farms. In general, good agreement was found between the PCR and the standard methods. The duplex real-time PCR assay developed in this study has proved to be a very sensitive and rapid tool that might provide a valuable addition to the methods currently available for routine diagnosis of ovine abortions.