Background Chronic infections with Chlamydia trachomatis (Ct) can give rise to sequelae that include pelvic inflammatory disease (PID), chronic pelvic pain (CPP), ectopic pregnancy (EP) and tubal factor infertility (TFI), and may contribute to cervical and ovarian cancer development in women. The humoral immune system of an infected individual recognizes and responds to different Ct antigens by eliciting a variety of antibodies. Based on differential protein expression, antibody patterns may represent infection-specific phases of the chlamydial life cycle or disease-specific stages. The selection of potential antigens for the development of serological assays is usually based on prior knowledge about antigenic properties and thus restricted to few selected proteins.

Methods To overcome this bias, we have developed a novel method to generate Ct whole-proteome microarrays directly from bacterial genomic DNA using a combination of multiple spotting technique and cell-free, on-chip protein expression based on expression constructs generated by two successive PCRs. Based on e.g. case-control comparisons, informative antigens are identified and validated in sero-epidemiological studies using low-density, high-throughput Luminex-based multiplex suspension array technology.

Results Establishment of the method for Ct serovar D with 895 open reading frames (ORFs) yielded several novel infection markers, and revealed an association between specific Ct antibodies and the development of cervical carcinoma (adjusted odds ratio (OR) 3.9, 95% confidence interval (CI) 1.8–8.3 for CT_117, and OR 3.1, 95% CI 1.3–7.1 for CT_223).

Conclusion Following this initial screening we aim to identify Ct antigens associated with PID, EP, TFI and ovarian cancer as well as antibody responses associated with protection from Ct re-infection. The newly developed technique for generation of fast and efficient proteome immunoassays can easily be adapted to other complex microorganisms, not only in the field of sexually transmitted infections but in all areas of infection research.

Disclosure No significant relationships.