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Fetal wastage as a consequence of Mycoplasma pulmonis infection in mice
Abstract:
The effect of Mycoplasma pulmonis, strain JB, on the outcome of pregnancy in TO mice was studied. The mice were infected intravenously before or after mating and the fetuses were examined at autopsy just before parturition. An increase in the number of abnormal pregnancies was noted in mice infected about 2 weeks before mating, and there was a significant increase in the number of fetuses which died mid-way through pregnancy. Mycoplasmas were not isolated from any of the fetuses although the organisms reached the joints of the pregnant mice and caused arthritis. It is possible, therefore, that maternal upset was a factor in these abnormal pregnancies. In mice infected at various times after mating, abnormal pregnancies were most frequently seen in those infected 9 days after mating. There was an increase in the number of both mid- and late-stage fetal deaths in these mice and also an increase in the number of late-stage fetal deaths in mice infected 5 days after mating. Mycoplasmas were isolated not only from most of the dead fetuses but also from living ones which suggests that in most instances death was probably due to maternal infection and disturbance rather than fetal infection per se. The possibility of modifying this mouse model by establishing a chronic genital tract infection is discussed as a means of investigating the role of mycoplasmas in human abortion.
Insights
Maternal infection with Mycoplasma pulmonis caused abnormal pregnancies and fetal deaths in mice. The study suggests maternal stress, not direct fetal infection, is the likely cause, informing research into human abortion.
Area of Science:
- Reproductive Immunology
- Microbiology
- Animal Models
Background:
- Mycoplasma pulmonis is a pathogen that can affect reproductive outcomes.
- Understanding the mechanisms of Mycoplasma-induced pregnancy complications is crucial.
Purpose of the Study:
- To investigate the impact of Mycoplasma pulmonis infection on pregnancy in TO mice.
- To determine the timing of infection relative to mating and its effect on fetal viability.
- To explore the potential role of maternal factors versus direct fetal infection in adverse pregnancy outcomes.
Main Methods:
- TO mice were infected intravenously with Mycoplasma pulmonis (strain JB) before or after mating.
- Pregnancy outcomes and fetal development were assessed at autopsy before parturition.
- Mycoplasma isolation was attempted from maternal tissues and fetuses (both living and dead).
Main Results:
- Infection approximately two weeks before mating led to increased abnormal pregnancies and mid-term fetal deaths.
- Infection after mating, particularly at 9 days post-mating, resulted in the highest frequency of abnormal pregnancies and both mid- and late-stage fetal deaths.
- Mycoplasmas were detected in maternal joints (arthritis) but not consistently in fetuses from pre-mating infections; however, they were isolated from most fetuses following post-mating infections.
- Maternal infection and subsequent distress appear to be the primary drivers of fetal death, rather than direct fetal infection.
Conclusions:
- Mycoplasma pulmonis infection significantly disrupts pregnancy in mice, with timing being a critical factor.
- Maternal inflammatory responses and systemic illness likely contribute to fetal demise.
- This mouse model offers potential for studying the role of mycoplasmas in human reproductive failure and abortion.