Enhancing the Efficacy of a Chlamydia Subunit Vaccine Through
Encapsulation
Chlamydia trachomatis (CT) is the world's leading cause of sexually transmitted diseases (STD) and the most commonly reported STD in the U.S. and Texas. Chlamydia infection may result in pelvic inflammatory disease, complications such as ectopic pregnancy and infertility in women, in addition to epididymitis in men, pneumonia in infants, and even blindness. A peptide, or protein-based, vaccine candidate has been demonstrated to have a high degree of efficacy in two animal models of genital chlamydial infection. However, there is a need to further develop this promising vaccine in terms of longerlasting protective immunity, easy and effective delivery, and improved efficacy in order to transition into humans. The objective of this project is to develop an effective, novel, encapsulated subunit Chlamydia vaccine that will be validated in an established animal (mouse) model of genital chlamydial infection. We hypothesize that the encapsulated vaccine formulation will perform better (e.g., higher and longer protective efficacy, longer stability, and fewer side effects) than the non-encapsulated vaccine formulation. For the technical tasks, SwRI performed encapsulation and characterization of subunit chlamydial antigens along with selected adjuvants, and in vivo evaluation of the performance of free and encapsulated vaccines.
SwRI performed peptide solubility, successfully encapsulated five different subunit peptide antigens, and also fabricated and characterized liposomes encapsulating an adjuvant (CPG). An animal vaccination study demonstrated that liposome-chlamydial protease/proteasome-like activity factor (CPAF), liposome-peptide, and peptide-only vaccination induced a robust Chlamydia muridarum specific Th1 cellular response. Compared to other vaccination groups, the liposome-peptide vaccination resulted in faster clearance of infection after a challenge with bacteria. Liposomepeptide vaccinated animals displayed minimal oviduct dilatation. These results indicate that apart from enhancing resolution of infection, vaccination with liposome-peptide induces protection against oviduct pathology.