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Is Pneumocystis carinii vertically transmitted to neonatal rats?
1Department of Parasitology, Seoul National University College of Medicine, Korea. hst@plaza.snu.ac.kr
Insights
Pneumocystis carinii rarely crosses the placenta. This study found limited evidence of transplacental transmission in neonatal rats, with lower infection rates compared to mothers.
Area of Science:
- Medical Mycology
- Immunocompromised Host Pathogens
Background:
- Pneumocystis carinii is a significant pulmonary pathogen in immunocompromised individuals.
- Transmission typically occurs via airborne routes, with most children infected early in life.
- Prenatal transplacental transmission of Pneumocystis carinii remains unproven.
Purpose of the Study:
- To investigate the potential for Pneumocystis carinii transplacental vertical transmission in a neonatal rat model.
- To assess the proliferation and detection of Pneumocystis carinii in neonatal rat lungs.
Main Methods:
- Experimental infection of immunosuppressed and normal maternal rats with Pneumocystis carinii.
- Diff-Quik staining of lung impression smears and in-situ hybridization for lung sections in neonatal rats.
- Comparison of infection rates and organism load between neonatal and maternal rats.
Main Results:
- 100% infection rate in immunosuppressed maternal rats versus 0% in normal mothers.
- Cystic forms of Pneumocystis carinii detected in 1-week-old neonatal rats born to infected mothers, but negative by in-situ hybridization.
- Lower counts of Pneumocystis carinii cystic forms and in-situ hybridization reactivity in neonatal rat lungs compared to maternal rats.
Conclusions:
- Pneumocystis carinii transmission through the placenta is rare.
- Pneumocystis carinii proliferates less effectively in the lungs of neonatal rats compared to their mothers.
Abstract:
Pneumocystis carinii is a pulmonary pathogen of immunocompromised humans or other mammals. Its infection results from activation of organisms involved in latent infection or from new infection through the air. Almost all children are known to be infected within 2 to 4 years of birth, though prenatal transplacental transmission has not yet been demonstrated. In this study we observed experimental P. carinii infection in neonatal rats, thus investigating the possibility of transplacental vertical transmission by Diff-Quik staining of the lung impression smears and in-situ hybridization for lung sections. The positive rate of P. carinii infection in immunosuppressed maternal rats was 100%, but that in normal maternal rats was 0%. Cystic forms of P. carinii were observed in three of six 1-week old neonatal rats born of heavily infected mothers, but none of them was positive by in-situ hybridization. Five weeks after birth, cystic forms were detected in four neonatal rats. In the lobes of the lungs, no predilection site of P. carinii was recognized. Counts of cystic forms on smears and the reactivity of in-situ hybridization in the lungs of neonatal rats were significantly lower than in maternal rats. The present findings suggest that P. carinii is rarely transmitted through the placenta and proliferates less successfully in the lungs of neonatal rats than in mothers.