Rapid Point-of-Care Detection of Human Papillomavirus

Project Summary The goal of this project is to demonstrate feasibility of a rapid (≤5 mins), sensitive system for the point-of-care (POC) detection of human papillomavirus (HPV) in human vaginal samples that integrates our patented detector of pathogens based on identification of species-specific, nucleic acid (NA) sequences. The detector relies on a patented electromechanical signal transduction mechanism that enables the low-cost, optics-free and amplification-free (e.g., no PCR) detection of DNA/RNA at ultralow concentration (~10-19 M). A compelling need persists for rapid (minutes), cost effective, POC NA detection devices for infectious disease diagnostics so as to facilitate prompt, well-informed therapies and counseling and to avoid potentially harmful actions including the inappropriate prescription of antibiotics. In earlier work, we demonstrated the detection of Neisseria gonorrhoeae (NG) with sensitivity of ~98% and specificity of ~100%. We currently are gathering similar data for detection of Chlamydia trachomatis (CT). Since HPV is the most common STI and the cause of slowly developing cervical cancers, it is a logical target for us to address in order to facilitate life-saving precancer screening. A key feature of our patented detector is the use of peptide nucleic acid (PNA) capture probes, which are uncharged polyamide analogs to NAs that share the same base chemistry. Since bead-PNA conjugates are designed to be charge neutral, they do not exhibit electrophoretic movement in the presence of a DC electric field. However, the substantial negative charge acquired upon capture of a target NA sequence makes the hybridized conjugate mobile. Electrophoresis of the bead-PNA conjugate with hybridized target NA to the mouth of a smaller diameter glass pore causes a significant increase in pore resistance, thereby resulting in a strong, sustained drop in measured ionic current. Nonspecifically bound NA is removed from the bead conjugate in the strong electric field at the pore mouth resulting in no sustained signal. Further, the opposing electroosmotic flow through the glass pore sweeps PNA-bead conjugates without hybridized target away from the pore mouth. In such a way, this simple conductometric device gives a highly selective (no observed false positives), binary response signaling the presence or absence of the target NA (and associated pathogen). This project focuses on three Aims: 1) Detection of highest risk HPV mRNA in media at ≤10-19 M (~60 copies/mL) and of HPV-infected human cells at ~5-10 cell/mL; 2) Development and testing of an integrated, lateral flow assay (LFA)-based prototype device for rapid (≤5 mins) detection of HPV-infected human cells at ~5-10 cells/mL; and 3) Demonstration of highest risk HPV detection in remnant clinical samples in 95% concordance with an approved commercial nucleic acid amplification test (NAAT). Successful achievement of these Aims will result in a device concept ready for manufacturable prototype development that is capable of HPV testing with competitive accuracy and with significant advantages of cost, rapidity, low power and robustness.