The 1B vaccine strain of Chlamydia abortus produces placental pathology indistinguishable from a wild type infection.

Chlamydia abortus is one of the most commonly diagnosed causes of infectious abortion in small ruminants worldwide. Control of the disease (Enzootic Abortion of Ewes or EAE) is achieved using the commercial live, attenuated C. abortus 1B vaccine strain, which can be distinguished from virulent wild-type (wt) strains by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Published studies applying this typing method and whole-genome sequence analyses to cases of EAE in vaccinated and non-vaccinated animals have provided strong evidence that the 1B strain is not attenuated and can infect the placenta causing disease in some ewes. Therefore, the objective of this study was to characterise the lesions found in the placentas of ewes vaccinated with the 1B strain and to compare these to those resulting from a wt infection. A C. abortus-free flock of multiparous adult ewes was vaccinated twice, over three breeding seasons, each before mating, with the commercial C. abortus 1B vaccine strain (Cevac® Chlamydia, Ceva Animal Health Ltd.). In the second lambing season following vaccination, placentas (n = 117) were collected at parturition and analysed by C. abortus-specific real-time quantitative PCR (qPCR). Two placentas, from a single ewe, which gave birth to live twin lambs, were found to be positive by qPCR and viable organisms were recovered and identified as vaccine type (vt) by PCR-RFLP, with no evidence of any wt strain being present. All cotyledons from the vt-infected placentas were analysed by histopathology and immunohistochemistry and compared to those from wt-infected placentas. Both vt-infected placentas showed lesions typical of those found in a wt infection in terms of their severity, distribution, and associated intensity of antigen labelling. These results conclusively demonstrate that the 1B strain can infect the placenta, producing typical EAE placental lesions that are indistinguishable from those found in wt infected animals.

Suppressed Immune-Related Profile Rescues Abortion-Prone Fetuses: A Novel Insight Into the CBA/J × DBA/2J Mouse Model.

The adverse clinical result and poor treatment outcome in recurrent spontaneous abortion (RSA) make it necessary to understand the pathogenic mechanism. The mating combination CBA/J × DBA/2 has been widely used as an abortion-prone model compared to DBA/2-mated CBA/J mice. Here, we used RNA-seq to get a comprehensive catalogue of genes differentially expressed between survival placenta in abortion-prone model and control. Five hundred twenty-four differentially expressed genes were obtained followed by clustering analysis, Gene Ontology analysis, and pathway analysis. We paid more attention to immune-related genes namely "immune response" and "immune system process" including 33 downregulated genes and 28 upregulated genes. Twenty-one genes contribute to suppressing immune system and 7 are against it. Six genes were validated by reverse transcription-polymerase chain reaction, namely Ccr1l1, Tlr4, Tgf-ß1, Tyro3, Gzmb, and Il-1ß. Furthermore, Tlr4, Tgf-ß1, and Il-1ß were analyzed by Western blot. Such immune profile gives us a better understanding of the complicated immune processing in RSA and immunosuppression can rescue pregnancy loss.

Multiple specificities of immunoglobulin M in equine fetuses infected with Leptospira interrogans indicate a competent immune response.

REASONS FOR PERFORMING STUDY: Foals of mares infected with Leptospira interrogans serovar Pomona type kennewicki (Lk) may be aborted/stillborn or delivered as healthy foals. Is fetal survival explained in part by the immune response of the fetus to Leptospira antigens? OBJECTIVES: To describe an outbreak of Leptospira abortion in which infected mares delivered dead/sick or normal foals and determine specificities of antibody in a collection of 54 fetuses from similar outbreaks. STUDY DESIGN: Outbreak investigation in combination with a case-control study of a larger set of samples from aborted fetuses. METHODS: Serology and polymerase chain reaction (PCR) on urine and amniotic fluids were used to diagnose infection during an outbreak of Leptospira abortion. Specificities of immunoglobulin (Ig)M, IgGa and IgGb for recombinant proteins of Lk in archived fluids of fetuses from similar outbreaks were compared by ELISA with those of fluids of fetuses not infected with Leptospira spp. RESULTS: Five fetuses of 11 infected mares in an outbreak survived in utero in the presence of persistent placental infection and were healthy at foaling. Fetuses of 6 mares in the outbreak were aborted or died soon after birth. Significantly greater (P<0.05) IgM reactivity with all recombinant proteins and with Lk sonicate was observed in 54 archived fluids from Leptospira infected fetuses than in fluids of 30 of non-Leptospira infected fetuses. Low levels of IgGa and IgGb specific for LipL32 and Lk sonicate and traces of LigA and Hsp15 specific IgGa were detected in a minority of archived fluids from Leptospira infected fetuses. CONCLUSION: Although mainly mediated by IgM, a high level of immune competence in aborted fetuses was evidenced by the multiplicity of Leptospira proteins targeted. This is likely to contribute to survival of foals in mares with evidence of placental infection at foaling as detailed in a typical outbreak.

Assessment of a fluorescent antibody test for the detection of antibodies against epizootic bovine abortion.

The current study was directed at developing and validating an indirect fluorescent antibody test (IFAT) capable of detecting antibodies specific for the agent of epizootic bovine abortion (aoEBA). Sensitivity and specificity was determined by comparing antibody titers from 114 fetuses infected with aoEBA with 68 fetuses diagnosed with alternate infectious etiologies. Data established specificity at 100% and sensitivity at 94.7% when cutoff criteria for a positive test were assigned at a titer of ≥1,000. Potential cross-reactivity was noted in samples from 3 fetuses with antibody titers of 10 or100; all were infected with Gram-positive organisms. The remaining 65 fetuses infected with microbes other than aoEBA, and an additional 12 negative reference sera, did not have detectable titers. The IFAT-based serology assay is rapid, reproducible, and unaffected by fluid color or opacity. Total fetal immunoglobulin (Ig)G was also evaluated as an aid for diagnosing EBA. Significantly higher concentrations of IgG were identified in fetuses infected with aoEBA as compared to those with alternate infectious etiologies. The presence of IgG is a sensitive indicator of EBA and increases the specificity of FAT-based serologic diagnosis when titers are 10 or 100. Taken together, serology and IgG analyses suggest that the incidence of EBA may be underestimated.

Abortion and premature birth in cattle following vaccination with Brucella abortus strain RB51.

Brucella abortus RB51 is the vaccine strain currently licensed for immunizing cattle against brucellosis in the United States. Most cattle are vaccinated as heifer calves at 4-12 months of age. Adult cattle may be vaccinated in selected high-risk situations. Two herds of pregnant adult cattle in the brucellosis-endemic area of Wyoming were vaccinated with a standard label dose (1.0-3.4 × 10(10) organisms) of RB51. Reproductive losses in the vaccinated herds were 5.3% (herd A) and 0.6% (herd B) and included abortions, stillbirths, premature calves, and unbred cows (presumed early abortion). Brucella abortus was cultured from multiple tissues of aborted and premature calves (7/9), and from placenta. Isolates were identified as B. abortus strain RB51 by standard strain typing procedures and a species-specific polymerase chain reaction. Bronchopneumonia with intralesional bacteria and placentitis were observed microscopically. There was no evidence of involvement of other infectious or toxic causes of abortion. Producers, veterinarians, and laboratory staff should be alert to the risk of abortion when pregnant cattle are vaccinated with RB51, to potential human exposure, and to the importance of distinguishing field from vaccinal strains of B. abortus.

Hematologic and IgG responses of heifers experimentally infected with the agent of epizootic bovine abortion.

BACKGROUND: Epizootic bovine abortion (EBA) is a tick-transmitted abortive disease of beef cattle in the western United States. Infected cattle do not have clinical signs until abortion occurs, usually within the last trimester of gestation. There is little information on the hematologic response of the dam following infection. OBJECTIVE: The purpose of this study was to determine if changes in blood leukocytes and serum IgG concentrations could be detected following experimental infection of pregnant heifers with the etiologic agent of EBA (aoEBA). METHODS: Twelve Angus heifers were infected during gestation with the aoEBA using an inoculum prepared from the thymus of an infected fetus. Five pregnant heifer controls were given an inoculum prepared from the thymus of an aoEBA-negative calf. PCVs, total and differential leukocyte counts, and serum IgG concentrations were measured weekly following administration of the inocula until abortion or calving. Gross and microscopic examinations were performed on all aborted fetuses to confirm infection. RESULTS: Eleven of 12 heifers in the treatment group aborted, and significant findings were decreased lymphocyte counts at weeks 1 and 14 postinoculation and increased monocyte counts at week 4 compared with control animals. Serum IgG concentrations were significantly increased at weeks 6-8 and 11 in the treatment group. CONCLUSIONS: Leukogram changes are subtle in infected cattle. Future research efforts should be aimed at development of an antibody test specific for detection of previously infected animals, which could graze safely on EBA-endemic pastures.

Identification of immunologically relevant proteins of Chlamydophila abortus using sera from experimentally infected pregnant ewes.

Chlamydophila abortus is an intracellular pathogen and the etiological agent of enzootic abortion of ewes (EAE). C. abortus has a biphasic development cycle; extracellular infectious elementary bodies (EB) attach and penetrate host cells, where they give rise to intracellular, metabolically active reticulate bodies (RB). RB divide by binary fission and subsequently mature to EB, which, on rupture of infected cells, are released to infect new host cells. Pregnant ewes were challenged with 2 x 10(6) inclusion forming units (IFU) of C. abortus cultured in yolk sac (comprising both EB and RB). Serum samples were collected at 0, 7, 14, 21, 27, 30, 35, 40, and 43 days postinfection (dpi) and used to identify antigens of C. abortus expressed during disease. Additionally, sera from fetal lambs were collected at 30, 35, 40, and 43 dpi. All serum samples collected from experimentally infected pregnant ewes reacted specifically with several antigens of EB as determined by one-dimensional (1-D) and 2-D gel electrophoresis; reactive antigens identified by mass spectrometry included the major outer membrane protein (MOMP), polymorphic outer membrane protein (POMP), and macrophage infectivity potentiator (MIP) lipoprotein.

Gender ratio distortion in abortuses and live births from patients with recurrent spontaneous abortion.

PROBLEM: Gender ratio of live birth in humans is approximately 1.05 and males are born a slightly more, while gender ratio of fertilization should be 1.00, suggesting that female fetus might be more sensitive to abortion than male fetus during pregnancy. METHOD OF STUDY: We examined karyotype of abortuses from patients with recurrent spontaneous abortion (RSA), who had at least one live birth before or after the treatment of RSA. RESULTS: Chromosomal abnormality was not frequent (14.6%) in the abortuses from the RSA patients. Among abortuses without chromosomal abnormality, male karyotype was rare (9.2%), and this gender ratio distortion was more prominent in RSA cases not carrying autoantibodies (3.5%) than that in the RSA cases carrying autoantibodies (26.3%), with statistical significance (P = 0.009). CONCLUSION: These observations suggested that the aborted fetuses from RSA of unknown etiology, i.e. no chromosomal abnormality and no autoantibody, were preferentially female.

Phenotypic analysis of circulating dendritic cells during the second half of human gestation.

Dendritic cells (DCs) have been characterized as having an immature phenotype in infants when compared with adults; but it is unclear whether the phenotype or function of these populations changes during human intrauterine development. Three-colour flow cytometry was used to phenotype fetal/neonatal circulating DCs during the second half (>20-wk gestation) of pregnancy, (n = 34) and adults (n = 9). DCs were identified from peripheral blood mononuclear cells (PBMCs) or cord blood mononuclear cells (CBMCs) as staining brightly for HLA-DR but negative for T cell, B cell, monocyte, and NK cell lineage markers. The surface molecule of interest was detected in a third colour. During gestation CD34, a marker of immaturity was significantly higher, and CD4, a differentiation marker, was significantly lower than adult levels. The percentage of CD11c+ cells did not differ significantly at any age, although a trend to reduced intensity of expression at earlier stages of gestation was observed. Significantly fewer DCs expressed the IgG receptors CD32 and CD64 at all gestations. The percentage of HLA-DR+/lin- cells expressing CD40 was lowest at 20-23 wks and was always significantly lower on DCs from cord blood vs. adult blood. Similarly, the percentage of CD86+ and CD54+ DCs was significantly lower than adults throughout gestation. Thus, immaturity of cord blood DCs is likely to arise as a consequence of decreased ability to take up antigen (at least via IgG-mediated mechanisms) and reduced provision of co-stimulation.

Experimental Coxiella burnetii infection in pregnant goats: a histopathological and immunohistochemical study.

Pregnant goats were inoculated subcutaneosly with Coxiella burnetii and the course of infection was studied. Abortion in the last third of pregnancy occurred in all infected animals. Tissues from the placenta and other organs were studied before and after abortion by immunohistochemistry and PCR analysis. After infection, mild lesions were observed in several maternal organs, mainly the mammary gland but also the lung and the liver. The trophoblast cells of the choriallantoic membrane were the first target cells of the placenta; there was, however, a substantial delay between initial infection and placental colonization. In the last weeks of pregnancy, just before abortion, massive bacterial multiplication was detected in the placenta. In this stage of infection a necrotic and suppurative placentitis separated the fetal trophoblast cells from maternal syncytial epithelium. Vasculitis was observed in the fetal mesenchyme. A strong maternal T-cell response was detected in the inter-placentomal areas but not in the placentomes, where only neutrophils and smaller numbers of macrophages were associated with the lesions. Neither lesions nor C. burnetii DNA were found in maternal organs in animals maintained until day 120 post-abortion.

The role of complement in pregnancy and fetal loss.

In the United States, between 1 and 3% of women suffer recurrent miscarriages; 50-70% of all conceptions fail. Although in the majority of affected women the cause of recurrent miscarriages is unknown, an immune mechanism involving the inappropriate and subsequently injurious recognition of the conceptus by the mother's immune system has been proposed. Murine models have recently been developed that are relevant to this issue. We and others have identified a novel role for complement as an early effector in the pathway leading to pregnancy loss associated with placental inflammation. Indeed, it appears that inhibition of complement activation is an absolute requirement for normal pregnancy, and that in the antiphosphospholid syndrome overwhelming activation of complement triggered by antibodies (Ab) deposited in placenta leads to fetal injury. Identification of complement activation as a mediator of pregnancy loss and definition of the complement components necessary to trigger such injury is likely to lead to a better understanding of its pathogenesis and to new and improved treatments.