Production, reproductive, and metabolic factors associated with chlamydial seropositivity and reproductive tract antigens in dairy herds with fertility disorders.

While chlamydial infections cause abortions in cattle, its role in other reproductive disorders is uncertain. This study identified the risk factors for chlamydial infection in herds with history of subfertility. We investigated the possible effects of coinfections, different metabolic parameters, abortion, ovarian cysts, pathological vaginal discharge, length of the open period, milk yield, housing conditions and age. In cows from 34 farms with elevated reproductive disorders, 41.5% had antibodies against chlamydia, while chlamydia antigen was detected in the vagina and uterus of 46.7%. A statistical relationship between seropositivity and antigen positivity was not found. Abortion (OR = 6.6) and loose housing (OR = 2.3) were risk factors for the presence of chlamydia antibodies. Furthermore, there were significant relationships between metabolic disorders and chlamydial infections. Increased levels of beta-hydroxybutaric acid (OR = 6.8) and hypocalcaemia (OR = 6.0) often accompanied chlamydia antigen in the vagina. Increased age (OR = 1.2) and pathological vaginal discharge (OR = 2.4) were identified as risk factors for chlamydia antigen in the vagina. The largest risk factor was for the association of ovarian cysts (OR = 21.5) with uterine antigen. In conclusion, chlamydial infection in dairy herd cows is best understood as a multifactorial disease.

Differences in cytokine mRNA profiles between naïve and in vivo-primed ovine PBMC after exposure to heat-inactivated Coxiella burnetii.

During human Coxiella burnetii (C. burnetii) infections, high IL-10 levels favor replication of C. burnetii in monocytes and development of chronic Q fever, whereas IFN-gamma promotes intracellular killing. Sheep are a common source for human C. burnetii infections, but in contrast to man become transiently infected only. In a first approach to unravel the role of cytokines during ovine C. burnetii infections, we investigated by semiquantitative RT-PCR whether heat-inactivated C. burnetii affects the transcription of genes coding for IL-2, IL-4, IL-10, and INF-gamma in vitro in PBMC from sheep seropositive or seronegative for C. burnetii. By computer-assisted evaluation of band intensities the transcription rate of the cytokine genes was quantified in relation to transcription in Concanavalin A-stimulated and nonstimulated controls. Transcription rates in PBMC from seropositive animals after incubation with C. burnetii for 4 hours strongly resembled those found in PBMC from seronegative sheep. However, upon prolonged incubation (24 h) C. burnetii induced an increased IL-10 transcription in PBMC from 2 of 5 seronegative, but in PBMC from 5 of 5 seropositive animals. The data suggest that natural C. burnetii infections prime the ovine immune system towards a T(H)2-like pattern and this action thereby represents the first clue for the involvement of ovine immune cells in the response to C. burnetii infections.

Detection of Chlamydia suis from clinical specimens: comparison of PCR, antigen ELISA, and culture.

Cell culture is still widely regarded as the gold standard in chlamydial diagnosis despite its well-known limitations in terms of sensitivity. On the other hand, the polymerase chain reaction (PCR) has emerged as a promising alternative because of rapidity and high sensitivity. However, validation of methodologies is required before the issue of standardization can be addressed. In the present study, 109 clinical samples (organ tissue, nasal, and faecal swabs) from pigs experimentally infected with Chlamydia suis were examined by cell culture, nested PCR in the ompA gene region, and two different antigen enzyme-linked immunosorbent assays (ELISAs) in order to compare the diagnostic performance of these methods. Culture and PCR produced the highest proportion of concordant results (kappa coefficient 0.712). Among 99 samples, 34 were positive in both assays, 51 were negative in both assays, 12 culture-negatives were positive in PCR, and only 2 culture-positives were negative in PCR. Thus, the sensitivity and specificity of PCR vs. culture as standard were 94.4% and 81.0%, respectively, whereas the corresponding values for culture vs. PCR as standard were 73.9% and 96.2%, respectively. Both ELISA tests performed considerably weaker. The data underline the potential of PCR as a powerful detection method for chlamydiae.

Coxiella burnetii plasmid types QpDG and QpH1 are closely related and likely identical.

Strains and isolates of Coxiella burnetii, an obligate intracellular bacterium, carry a single plasmid or a plasmid-homologous sequence integrated into the chromosome. The plasmids QpH1, QpRS, QpDV and the chromosome-integrated plasmid-homologous region have been completely sequenced, whereas no sequence data are available for the QpDG plasmid. In this study, we used total genomic DNA from reference strain C. burnetii Dugway 5J108-111 to demonstrate and characterize the QpDG plasmid by pulsed-field gel electrophoresis (PFGE) and Southern hybridization. Primers derived from regions shared among C. burnetii plasmids were used to construct a physical map of the QpDG plasmid by extra long (XL) PCR. Both approaches, Southern hybridization and XL PCR indicated that QpDG and QpH1 represent a closely related and likely identical plasmid.