PubMed · 7101712
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A H Miller. 1982-05-15. Risk from chlamydia.. https://doi.org/10.1136/vr.110.20.482
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The parasite Neospora caninum is an important cause of abortion in cattle world-wide. Chronically infected dams transmit the parasite transplacentally and infected foetuses may be aborted or born chronically infected but clinically normal. Chronically infected cows repeatedly transmit the parasite to foetuses in several pregnancies and some may abort more than once suggesting that the immune response in these cattle is compromised during pregnancy. To investigate the nature of the immune response in chronically infected cattle, five naturally, chronically infected cows were challenged with N. caninum tachyzoites at 10 weeks of gestation. No foetopathy occurred and all five delivered live calves at full-term. In four naive pregnant cows challenged at the same time, all four foetuses died within 3-5 weeks of challenge. Of the five live calves born to the chronically infected challenged cows, three were transplacentally infected with N. caninum. The kinetics of the maternal anti-N. caninum antibody responses during gestation suggested that these transplacental infections were not the result of the superimposed challenge, but the result of the recrudescence of the maternal chronic infection-which occurred concurrently in non-challenged, chronically infected pregnant controls. These data provide the first experimental evidence that protective immunity occurs in neosporosis. They also suggest that whilst immunity to a pre-existing infection will protect against an exogenous challenge, this protective immunity will not prevent transplacental infection. This implies that a subtle form of concomitant immunity exists in chronically infected cattle and has important implications for vaccine development.
We used a combined cross-sectional and longitudinal design to estimate seroprevalence of Brucella antibodies in Awassi sheep and the incidence of abortion due to brucellosis during one lambing season, and to test risk factors. The Brucella organisms isolated from aborted fetuses and vaginal swabs were characterized as Brucella melitensis biotype 3. Seventy Awassi sheep flocks were selected randomly from Northern Jordan. Sixty two of the 70 flocks were used in the cross-sectional study and 8 flocks were monitored for three consecutive months to estimate the incidence of abortion. Questionnaire data and 602 serum samples were collected and analyzed. Thirty five flocks (56%) were brucellosis-seropositive by the Rose Bengal plate-agglutination test (RBT) and 28 (45%) by enzyme-linked immunosorbent assay (ELISA). The crude seroprevalence of brucellosis at the individual-animal level was 14.3% by RBT, 7.2% by ELISA and 2.2% using both tests in series. The flock-specific, animal-level abortion risk ranged between 2.5 and 50% (median=22.6%). The flock brucellosis-status was used as the outcome variable in a multivariable logistic regression. Grazing at communal pasture increased odds, but usage of disinfectants, previous vaccination for brucellosis, and tap water were protective. The animal-level incidence of abortion was 20% and the specific incidence risk of abortion due to brucellosis was 13%.
To understand the molecular pathology of factor XIII (FXIII) deficiency in vivo, its A subunit (FXIIIA)-knockout (KO) mice were functionally analyzed. Although homozygous FXIIIA female KO mice were capable of becoming pregnant, most of them died due to excessive vaginal bleeding during gestation. Abdominal incisions revealed that the uteri of the dead mice were filled with blood and that some embryos were much smaller than others within a single uterus. A series of histologic examinations of the pregnant animals suggested that massive placental hemorrhage and subsequent necrosis developed in the uteri of the FXIIIA KO mice on day 10 of gestation. This was true regardless of the genotypes of fetuses. These results are reminiscent of spontaneous miscarriage in pregnant humans with FXIII deficiency and indicate that maternal FXIII plays a critical role in uterine hemostasis and maintenance of the placenta during gestation.