Development of a Chlamydia trachomatis T cell Vaccine

The immune correlates of protection for most of the currently used vaccines are based on long-lived humoral immunity. Vaccines based on humoral immunity alone are unlikely to protect against infections caused by intracellular pathogens and today's most pressing infectious diseases of public health importance are caused by intracellular infections that not only include Chlamydia trachomatis but also tuberculosis, malaria, and HIV/AIDS. For these infections, vaccines that induce cellular immune responses are essential. Major impediments in developing such vaccines include difficulty in identifying relevant T cell antigens and delivering them in ways that elicit protective cellular immunity. In turn this is compounded by the complexity and plasticity of T cell developmental pathways that often correlate with specific aspects of protective immunity. Genomics and proteomics now provide tools to allow unbiased selection of candidate T cell antigens. This review mainly focuses on an immunoproteomic approach used in our laboratory to identify Chlamydia T cell antigens and how these T cell antigens can be developed into a future human Chlamydia vaccine.