METHODS: Uteri from ovariectomized, female Sprague-Dawley rats receiving seven days estradiol, progesterone or genistein (25, 50 and 100mg/kg/day) were harvested and levels of AQP-1, 2, 5 and 7 proteins and mRNAs were determined by Western blotting and Real-time PCR (qPCR) respectively. Distribution of these proteins in uterus was observed by immunohistochemistry.
RESULTS: Genistein caused a dose-dependent increase in uterine AQP-1, 2, 5 and 7 protein and mRNA expression, however at the levels lower than following estradiol or progesterone stimulations. Effects of genistein were antagonized by estradiol receptor blocker, ICI 182780. Estradiol caused the highest AQP-2 protein and mRNA expression while progesterone caused the highest AQP-1, 5 and 7 protein and mRNA expression in uterus. AQP-1, 2, 5 and 7 protein were found to be distributed in the myometrium as well as in uterine luminal and glandular epithelia and endometrial blood vessels. In conclusion, the observed effects of estradiol, progesterone and genistein on uterine AQP-1, 2, 5 and 7 expression could help to explain the differences in the amount of fluid accumulated in the uterus under these different conditions.
METHODOLOGY/PRINCIPAL FINDINGS: With the availability of the B. pseudomallei whole genome sequence, we undertook to identify genes encoding the known immunogenic outer membrane protein A (OmpA). Twelve OmpA domains were identified and ORFs containing these domains were fully annotated. Of the 12 ORFs, two of these OmpAs, Omp3 and Omp7, were successfully cloned, expressed as soluble protein and purified. Both proteins were recognised by antibodies in melioidosis patients' sera by Western blot analysis. Purified soluble fractions of Omp3 and Omp7 were assessed for their ability to protect BALB/c mice against B. pseudomallei infection. Mice were immunised with either Omp3 or Omp7, subsequently challenged with 1x10(6) colony forming units (cfu) of B. pseudomallei via the intraperitoneal route, and examined daily for 21 days post-challenge. This pilot study has demonstrated that whilst all control unimmunised mice died by day 9 post-challenge, two mice (out of 4) from both immunised groups survived beyond 21 days post-infection.
CONCLUSIONS/SIGNIFICANCE: We have demonstrated that B. pseudomallei OmpA proteins are immunogenic in mice as well as melioidosis patients and should be further assessed as potential vaccine candidates against B. pseudomallei infection.