The immunological determinants of protective immunity and immunopathology in trachoma

Current trachoma control strategies focus on reducing the burden of C. trachomatis infection within endemic communities through the use of repeated mass antibiotic distribution and other measures to suppress transmission, such as improved water supply and sanitation. However, the long-term effectiveness of these interventions in halting the progression of the scarring complications of trachoma is unknown, as the conjunctival inflammation often persists and new cases of scarring complications (trichiasis) continue to develop in formerly endemic communities long after C. trachomatis becomes undetectable.

There is currently a considerable amount of effort being put into the development of an anti-chlamydial vaccine, which offers the hope that repeated mass antibiotic treatment of endemic populations would become un-necessary. However, vaccine development is hindered by a limited understanding of what constitutes a protective versus a pathogenic immune response to C .trachomatis.

The aim of this project is to investigate the interaction between the human immune response and chlamydial infection. We are examining the host gene expression at the site of infection, drivers of chornic inflammation (C. trachomatis and other bacterial or viral species), pathogen virulence / genetic diversity, and anti-chlamydial serology in longitudinal samples from a cohort of around 500 children in a trachoma-endemic region of northern Tanzania.

These data will be analysed in order to determine their association with clinical disease signs and scarring progression over the four-year study period. This will enable us to identify the key epidemiological and immunological events that contribute to disease and to assess whether these events can be interrupted by interventions such as treatment or vaccination.