The plethora of ocular, genital and
respiratory diseases of Chlamydia, including nongonococcal
urethritis,
cervicitis pelvic inflammatory disease,
ectopic pregnancy, tubal factor
infertility,
conjunctivitis, blinding
trachoma and
interstitial pneumonia, and
chronic diseases that may include
atherosclerosis,
multiple sclerosis, adult onset
asthma and
Alzheimer's disease, still pose a considerable public health challenge to many nations. Although
antibiotics are effective against Chlamydia when effectively diagnosed,
asymptomatic infections are rampart, making clinical presentation of complications often the first evidence of an
infection. Consequently, the current medical opinion is that an effective prophylactic
vaccine would constitute the best approach to protect the human population from the most severe consequences of these
infections. Clinical and experimental studies have demonstration that Chlamydia immunity in animals and humans is mediated by T cells and a complementary antibody response, and the completion of the genome sequencing of several isolates of Chlamydia is broadening our knowledge of the immunogenic
antigens with potential
vaccine value. Thus, major advances have been made in defining the essential elements of a potentially effective
subunit vaccine design and parameters for evaluation. However, the challenge to develop effective delivery systems and human compatible adjuvants that would boost the immune response to achieve long-lasting protective immunity remains an elusive objective in chlamydial
vaccine research. In response to evolving molecular and cellular technologies and novel vaccinology approaches, considerable progress is being made in the construction of novel delivery systems, such as
DNA and plasmid expression systems, viral vectors, living and nonliving bacterial delivery systems, the use of chemical adjuvants,
lipoprotein constructs and the codelivery of
vaccines and specific immuno-modulatory
biological agonists targeting receptors for
chemokines,
Toll-like receptors, and costimulatory molecules. The application of these novel delivery strategies to Chlamydia
vaccine design could culminate in timely achievement of an efficacious
vaccine.