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Ureaplasma parvum serovar 3 multiple banded antigen size variation after chronic intra-amniotic
James W Robinson1, Samantha J Dando, Ilias Nitsos
1Institute of Health & Biomedical Innovation, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia.
Abstract:
Ureaplasma species are the microorganisms most frequently associated with adverse pregnancy outcomes. The multiple banded antigen (MBA), a surface-exposed lipoprotein, is a key virulence factor of ureaplasmas. The MBA demonstrates size variation, which we have shown previously to be correlated with the severity of chorioamnion inflammation. We aimed to investigate U. parvum serovar 3 pathogenesis in vivo, using a sheep model, by investigating: MBA variation after long term (chronic) and short term (acute) durations of in utero ureaplasma infections, and the severity of chorioamnionitis and inflammation in other fetal tissues. Inocula of 2 × 10(7) colony-forming-units (CFU) of U. parvum serovar 3 (Up) or media controls (C) were injected intra-amniotically into pregnant ewes at one of three time points: day 55 (69d Up, n = 8; C69, n = 4); day 117 (7d Up, n = 8; C7, n = 2); and day 121 (3d Up, n = 8; C3, n = 2) of gestation (term = 145-150d). At day 124, preterm fetuses were delivered surgically. Samples of chorioamnion, fetal lung, and umbilical cord were: (i) snap frozen for subsequent ureaplasma culture, and (ii) fixed, embedded, sectioned and stained by haematoxylin and eosin stain for histological analysis. Selected fetal lung clinical ureaplasma isolates were cloned and filtered to obtain cultures from a single CFU. Passage 1 and clone 2 ureaplasma cultures were tested by western blot to demonstrate MBA variation. In acute durations of ureaplasma infection no MBA variants (3d Up) or very few MBA variants (7d Up) were present when compared to the original inoculum. However, numerous MBA size variants were generated in vivo (alike within contiguous tissues, amniotic fluid and fetal lung, but different variants were present within chorioamnion), during chronic, 69d exposure to ureaplasma infection. For the first time we have shown that the degree of ureaplasma MBA variation in vivo increased with the duration of gestation.
Insights
Ureaplasma parvum serovar 3 causes adverse pregnancy outcomes. Its MBA virulence factor varies in size, increasing with infection duration, correlating with chorioamnionitis severity in a sheep model.
Area of Science:
- Reproductive Medicine
- Microbiology
- Immunology
Background:
- Ureaplasma species are linked to adverse pregnancy outcomes.
- The multiple banded antigen (MBA) is a Ureaplasma virulence factor.
- MBA size variation correlates with chorioamnion inflammation severity.
Purpose of the Study:
- Investigate Ureaplasma parvum serovar 3 pathogenesis in vivo.
- Analyze MBA variation during acute and chronic intrauterine infections.
- Assess chorioamnionitis and fetal tissue inflammation severity.
Main Methods:
- Sheep model for intrauterine Ureaplasma parvum infections (acute and chronic).
- Intra-amniotic inoculation of U. parvum or media controls at different gestational ages.
- Histological analysis of chorioamnion, fetal lung, and umbilical cord; ureaplasma culture; Western blot for MBA variation.
Main Results:
- Acute Ureaplasma infection showed minimal MBA variation.
- Chronic infection (69 days) resulted in numerous MBA size variants in vivo.
- MBA variation increased with the duration of intrauterine infection, correlating with inflammation.
Conclusions:
- Ureaplasma MBA size variation is a dynamic process occurring in vivo.
- MBA variation increases with prolonged intrauterine infection duration.
- MBA variation is linked to the severity of chorioamnionitis and fetal inflammation.
