The Development and Validation of a High-throughput Screening Method for Chlamydia trachomatis

Abstract

High-throughput screening is a scientific method that can be used to identify small compounds with activity against a number of bacteria and other organisms, as well as diseases, such as cancer, in a cost efficient manner within reasonable time frames. The absence of an effective HTS method for large-scale compound screening in Chlamydia hinders the identification of anti-chlamydial compounds that could serve as novel therapeutics, model molecules for the development of specific treatments, or molecular probes to gain insight into the basic biology of the organism. The absence of a high-throughput screening method is highly influenced by the obligate, intracellular nature of the organism, making enumeration of infection a time consuming and labor-intensive task, traditionally performed using an immunofluorescence assay. Recently in our laboratory, a new method for enumerating chlamydial infection was developed using a cell viability indicator, resazurin, to measure the reducing capability of the infected, eukaryotic host cells. In this study, the resazurin-based microplate assay was adapted to a high-throughput screening format and validated by screening the Prestwick Chemical library, containing many known anti-bacterial compounds, including anti-chlamydial compounds. An orthogonal assay was performed to further confirm the novel hits identified in the screen of the Prestwick Chemical library and to begin to identify the mechanisms of inhibition exuded on Chlamydia by those compounds. This high-throughput screening method was further adapted to automated liquid handling, including, plating and infecting the eukaryotic host cells, and the assay quality and reproducibility were verified by the HTS Facility at The University of Kansas in Lawrence, Kansas.