Development of a Chlamydia trachomatis bacterial ghost vaccine to fight human blindness

Abstract

Trachoma is the world’s leading cause of preventable disease and the third most common cause of blindness after cataract and glaucoma, affecting an estimated 84 million people and leaving 590 million at risk. As a crippling disease, Trachoma causes an enormous loss of productivity and constitutes a major socioeconomic burden. Although antibiotics are effective in treating active cases of the illness, they do not prevent re-infection, which occurs with high frequency in susceptible populations. Also, once infection and pathology are established, treatment may be less effective. Another major public health challenge posed by trachoma is that a large number of infected individuals are asymptomatic and readily infect those with whom they interact. Thus, an inexpensive and easy to deliver vaccine for trachoma would be highly effective in reducing the devastation caused by this disease. Development of an effective vaccine for controlling and preventing trachoma will require an understanding of the complex immunological mechanisms that occur during infection, identifying those antigens that elicit a protective immune response and designing effective vaccine delivery systems. Significant progress has been made in the delineation of the immune correlates of protection that will form the basis of vaccine evaluation. Recent advances in chlamydial genomics and proteomics has identified a number of protective antigens or epitopes that when appropriately delivered will produce an efficacious vaccine. The challenge at this time is the development of effective methods for vaccine delivery. We have developed an effective bacterial ghost (BG) delivery system possessing intrinsic adjuvant properties and capable of simultaneously delivering multiple antigens to the immune system. Such a flexible delivery system can produce an effective vaccine that will prevent the development of trachomatous conjunctivitis and blindness. The safety and relatively cheap production cost of BG-based vaccines offer a technological and manufacturing advantage for a vaccine needed on a global scale.