The effect of Toxoplasma gondii infection in unvaccinated and iscom-vaccinated pregnant ewes as monitored by plasma levels of 15-ketodihydroprostaglandin F2 alpha, progesterone, and oestrone sulphate

High Toxoplasma gondii frequency of infection in the genital tract of ewes previously positive for the parasite DNA in meat, in Sidi Bouzid, Tunisia

The aim of the present study was to estimate the molecular prevalence of T. gondii along various segments of the genital tract of confirmed chronically infected ewes. Genital tracts were collected from 42 ewes; meat samples from the same ewes were previously confirmed positive for T. gondii DNA. The whole DNA was extracted from 4 parts of the genital tract (ovary, horns, body of the uterus and vagina). PCR was used to amplify a 114 base-pairs of T. gondii B1 gene. For all studied samples, 95.2 % had at least one infected genital part. Toxoplasma gondii infection was confirmed by sequencing 20 amplicons randomly chosen. The majority of infected animals has 4 T. gondii-infected genital anatomical parts. Principal component analysis (PCA) revealed a cluster of adult animals (>24 months) with positive PCR in the ovaries and the vagina and another cluster of Barbarine animals having positive PCR in the horns and body of the uterus. General linear model confirmed PCA results and showed a significant higher prevalence of T. gondii in the ovaries and vagina of older animals (p = 0.001 and p = 0.02, respectively) and a higher prevalence of T. gondii in the horns of the uterus of Barbarine animals (p = 0.03). Toxoplasma gondii seems to highly persist along the various segments of the ewe's genital tract but further investigations are necessary to link such prevalence with the pathological implications.

Peripheral and placental immune responses in sheep after experimental infection with Toxoplasma gondii at the three terms of gestation

Although it is known that gestation could influence the clinical course of ovine toxoplasmosis, the precise effect of the term of gestation when sheep are infected are yet mostly unknown. The aim of this study was to evaluate the peripheral and placental immune responses developed in pregnant sheep after experimental infection with Toxoplasma gondii at different times of gestation. Thirty-six pregnant sheep were allocated in different groups, orally inoculated with sporulated oocysts of T. gondii at early, mid and late gestation and culled within 30 days post-infection. The peripheral humoral and cytokine responses were evaluated, as well as the transcription of cytokines at the placenta. Serological analysis revealed that, regardless the term of gestation when infected, specific IgG against T. gondii were detected from day 8 post-infection and there was an early peripheral release of IFN-γ at the first week post-infection followed by a short peak of IL10 and TNF-α at the second week post-infection. There were no significant differences in this response between infected groups. At the placenta, a similar increase in transcription of IFN-γ, and TNF-α was found at the three terms of gestation, while IL-4 increased mainly at the first and second terms and IL-10 transcription was higher at the last term. While these findings show that both Th1 and Th2 cytokines play a key role in the pathogenesis of ovine toxoplasmosis and that placental and peripheral immune responses do not closely correlate, there seems to be no clear modulation of these responses along the gestation.

The role of hormones on Toxoplasma gondii infection: a systematic review

Background:Toxoplasma gondii is the causal agent of toxoplasmosis in which one third of the world's population has been infected. In pregnant women, it may cause abortion and severe damage to the fetal central nervous system. During pregnancy, the prevalence of toxoplasmosis increases throughout the second and third quarter of gestation, simultaneously progesterone and 17β-estradiol also increase. Thus, it has been suggested that these hormones can aggravate or reduce parasite reproduction. The aim of this study was reviewing the relationship between hormones and infection caused by T. gondii in several experimental animal models and humans, focused mainly on: (a) congenital transmission, (b) parasite reproduction, (c) strain virulence, (d) levels of hormone in host induced by T. gondii infection, and (e) participation of hormone receptors in T. gondii infection. Are the hormones specific modulators of T. gondii infection? A systematic review methodology was used to consult several databases (Pub Med, Lilacs, Medline, Science direct, Scielo, Ebsco, Sprinker, Wiley, and Google Scholar) dated from September, 2013 to March, 2014.

Results: Thirty studies were included; eight studies in humans and 22 in animals and cell cultures. In the human studies, the most studied hormones were testosterone, progesterone, prolactin, and 17β-estradiol. Type I (RH and BK) and Type II (Prugniaud, SC, ME49, T45, P78, and T38) were the most frequent experimental strains.

Conclusions: Thirty-five years have passed since the first studies regarding T. gondii infection and its relationship with hormones. This systematic review suggests that hormones modulate T. gondii infection in different animal models. However, given that data were not comparable, further studies are required to determine the mechanism of hormone action in the T. gondii infectious process.

Mic1-3 Knockout Toxoplasma gondii is a good candidate for a vaccine against T. gondii-induced abortion in sheep

This study assessed the effectiveness of a mutant strain of Toxoplasma gondii (RH strain) lacking the mic1 and mic3 genes (Mic1-3KO) against Toxoplasma abortion in sheep. Ewes were inoculated subcutaneously with 10⁵ Mic1-3KO tachyzoïtes in three independent experiments. Following vaccination, Mic1-3KO induced a mild febrile response and serum IgG antibodies, which persisted throughout the experiments. Tissue cysts formed in the sheep, but were not, under our experimental conditions, infectious when given orally. Ewes were mated two months after vaccination and were orally challenged with the PRU strain of T. gondii at mid-gestation (400 oocysts in Experiments 1 and 2; 100 oocysts in Experiment 3). Challenge of vaccinated pregnant ewes resulted in a slight febrile response, whereas unvaccinated ewes developed a more severe, characteristic febrile response of longer duration. After challenge, all unvaccinated ewes aborted whereas 62%, 91% and 64% (Experiments 1, 2 and 3 respectively) of the lambs from vaccinated ewes were viable, with no clinical signs of infection. Mic1-3KO was as effective as S48, the strain used as a live vaccine for sheep (Toxovax^®). A dose of 10⁵ Mic1-3KO tachyzoites was sufficient to induce protection (versus a dose of 2 × 10⁶). Both subcutaneous and intraperitoneal injections were effective. Moreover, preliminary results showed the potential of Mic1-3KO to reduce the development of tissue cysts in lambs born to vaccinated ewes. This study demonstrates that Mic1-3KO is a potent vaccine candidate.

Foetal loss in dairy goats: function of the adrenal glands, corpus luteum and the foetal-placental unit

To investigate the causes and mechanisms of foetal loss in Norwegian dairy goats, blood parameters in 40 goats that lost foetuses were compared with those in 40 goats that experienced a normal pregnancy. High mean levels of 15-ketodihydro-PGF2alpha, and low mean levels of oestrone sulphate throughout pregnancy were associated with foetal loss. The mean oestrone sulphate level was low before abortion, and the distinct peak that occurred at parturition in the control goats was not observed in connection with abortion. Association of other blood parameters with foetal loss was not detected. Infectious agents and toxins did not appear to be major causes of foetal loss in this study. The normal level of progesterone and cortisol in goats with foetal loss indicated that the function of the corpus luteum and adrenal glands, respectively, were not disturbed. The rapid decline in progesterone level associated with foetal loss may therefore be a result, rather than the cause, of foetal death. The lowered level of oestrone sulphate and elevated level of 15-ketodihydro-PGF2alpha in goats with foetal loss clearly indicated that the endocrine foetal-placental function was disturbed.

Effect of experimental infection with Listeria monocytogenes on the development of pregnancy and on concentrations of progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha in the goat

The effect of Listeria monocytogenes infection on hormone levels in pregnant goats was studied. Four goats (Group I) received an intravenous inoculation of a bacterial culture (Type 1) on Days 69-77 and another four goats (Group II) received a similar inoculation on Days 105-106 of gestation. Five non-inoculated goats were used as controls. Plasma was analysed for progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha. The status of the foetus was followed using real-time ultrasonography. Three of the four goats in Group I aborted 8-10 days after inoculation. The fourth goat gave birth to a normal live kid at term. The three goats which aborted showed clinical signs of disease in connection with abortion. In Group II, all goats aborted after 9-11 days. All the goats showed clinical symptoms of disease from a few days after inoculation and the symptoms continued until abortion. The clinical symptoms of disease were more pronounced in Group II than in Group I. L. monocytogenes was isolated from all aborted foetuses. None of the control goats aborted. Ultrasound examination revealed foetal death either immediately before or up to 2 days before abortion. Mummification had begun in the foetus that had been dead for 2 days before expulsion. In comparison with pre-inoculation plasma levels in Group I, a significant decrease (P < 0.05) in progesterone levels and an increase in 15-ketodihydro-PGF2 alpha levels were observed from Days 4 and 6 after inoculation, respectively. In Group II, a significant decrease (P < 0.05) in progesterone levels and an increase in 15-ketodihydro-PGF2 alpha levels in plasma were observed from Days 8 and 6, respectively. The oestrone sulphate levels decreased slightly in the inoculated goats a few days before abortion. The pattern of changes in levels around abortion was similar to the pattern present in the control animals around parturition. However, oestrone sulphate levels did not increase in the inoculated groups before abortion in contrast to goats which delivered healthy kids. The changes in levels of 15-ketodihydro-PGF2 alpha in goats that aborted indicated that the endocrine foetal-placental function was disturbed, which was most likely due to the establishment and development of L. monocytogenes in the placenta and foetus.

Effect of Toxoplasma gondii infection on the development of pregnancy and on endocrine foetal-placental function in the goat

The effect of Toxoplasma gondii inoculation on pregnancy and on endocrine foetal-placental function in pregnant goats was studied. Five susceptible goats were inoculated subcutaneously with T. gondii bradyzoites at 71 +/- 2 days of gestation. Another five goats were used as controls. Plasma was analysed for progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha. The condition of the foetuses was monitored by real-time ultrasonography. All inoculated goats aborted or delivered stillborn or weak kids 54-73 days after inoculation. None of the goats showed signs of general disease. In cases of foetal death, the ultrasound examination revealed that death occurred between day 1 and 12 before abortion or birth. The appearance of the foetuses varied from fresh to mummified, depending on the number of days between foetal death and expulsion. All five goats became serologically positive to T. gondii after inoculation. None of the goats used as controls aborted, but one goat delivered one mummified and one weak kid for unknown reasons. In inoculated animals an increase in 15-ketodihydro-PGF2 alpha levels in plasma and a subsequent tendency to a decrease in oestrone sulphate levels were observed from about day 40 after inoculation and until abortion or birth. High levels of 15-ketodihydro-PGF2 alpha were seen after foetal death. High levels of 15-ketodihydro-PGF2 alpha were not always followed by a drop in progesterone levels. The mean level of progesterone was slightly decreased after inoculation and onwards. The pattern of progesterone levels around abortion in the inoculated goats was very similar to the pattern around parturition in the control goats. However, 15-ketodihydro-PGF2 alpha levels were higher both before and after abortion in inoculated goats than in control goats. The level of oestrone sulphate did not increase in the inoculated group before abortion in contrast to the level in goats which delivered healthy kids. The patterns of changes in levels of 15-ketodihydro-PGF2 alpha and oestrone sulphate in inoculated animals indicate that the endocrine foetal-placental function was disturbed in most of the inoculated goats, probably due to the injury caused by the establishment and development of T. gondii infection in the placenta and foetus.

Levels of 15-ketodihydroprostaglandin F2 alpha during experimental Toxoplasma gondii infection in non-pregnant ewe lambs

In order to study the relation between prostaglandin F2 alpha levels and fever during Toxoplasma gondii infection, six non-pregnant ewe lambs were exposed orally to T. gondii oocysts and an additional four animals were used as non-inoculated controls. Rectal temperature was measured daily during four weeks and plasma samples were analysed for the content of 15-ketodihydroprostaglandin F2 alpha. As compared to controls, the inoculated animals had significantly elevated rectal temperatures on days 4-16 after infection, but no concomitant changes in prostaglandin F2 alpha metabolite levels were recorded.