A novel guinea pig model of Chlamydia trachomatis genital tract infection.

Genital Chlamydia trachomatis infections often result in pelvic inflammatory disease and sequelae including infertility and ectopic pregnancies. In addition to the already established murine models, the development of other animal models is necessary to study the safety and efficacy of prototype vaccine candidates. The intravaginal infection of guinea pigs with C. trachomatis has been tested in three independent studies. The first two studies investigated the effect of hormonal treatment of the animals prior to infection with serovars D and E. The results showed that estradiol treatment was required for sustained infection. The third study conducted an immunization-challenge experiment to explore the feasibility of measuring protection in this guinea pig model. C. trachomatis bacteria were sampled using vaginal swabs and measured by qPCR. Using immunohistochemistry the bacteria were detected in the oviducts 19 days post-infection, indicating that the estradiol treatment resulted in ascending infection. Furthermore, immunization of guinea pigs with live EB formulated with ISCOM matrix led to reduction of cervico-vaginal shedding and diminished the severity of pathology. In this study we have developed a new guinea pig model of C. trachomatis female genital tract infection for the purpose of evaluating potential vaccine candidates.

Identification and molecular cloning of functional chicken IL-12.

By a combination of large-scale sequencing, bioinformatics, and traditional molecular biology, we identified the long-searched-for cDNA sequences encoding the homologues of the chicken IL-12p35 and IL-12p40 chains. These molecules are the first discovered nonmammalian IL-12 subunits. The homologies of the chicken IL-12p35 and IL-12p40 proteins to the corresponding known subunits of various species, i.e., humans, sheep, horse, cat, bovine, mouse, and woodchuck, ranged between 21 and 42%, respectively. The expression of IL-12 subunits was observed in lymphoid cells and proved to be dependent on the cell type and stimulus, while expression was not detected in stimulated primary chicken embryo fibroblast cells. Following transient expression of both molecules in COS-7 cells, we confirmed the necessity of heterodimerization into IL-12p70 to yield bioactivity as was also shown for its mammalian counterparts. The chicken IL-12p70 molecule, generated either by transient coexpression of monomeric IL-12p35 and monomeric IL-12p40 or as a fusion protein (as in a fusion linker construct), induced IFN-gamma synthesis and proliferative activity of freshly exposed chicken splenocytes. The high degree of functional similarity between chicken IL-12 and IL-12 of higher mammalian vertebrates, despite their poor sequence homology, illustrates the conservation and vital importance of the IL-12 molecule since the evolutionary dichotomy of birds and mammals >300 million years ago. In this article, we describe the first nonmammalian IL-12 molecule and show that this chicken IL-12 molecule is bioactive.