At a Glance
Researchers at Colorado State University have developed a straightforward paper treatment to immobilize proteinase K onto paper-based testing strips to enable accurate detection of active tuberculosis infection. These paper-based strips allow for point-of-care pre-treatment of patient urine samples without the use of tedious and time-consuming laboratory intervention.
Advantages of such paper-based strips include low-cost, ease of fabrication, wide availability, and self-wetting making them an ideal substrate for POC applications for the developing world. In addition, the novel immobilization strategy developed here can be beneficial to almost all enzyme properties, such as activity, specificity, selectivity, reduction of inhibition and aforementioned stability.
While an estimated quarter of the world is latently infected with Mycobacterium Tuberculosis (Mtb), active Tuberculosis (TB) is caused by uncontrolled infection leading to a predominantly respiratory and transmissible disease.
According to the recent WHO report 7.1 million people (globally) with TB were reported to have been diagnosed in 2019 – a small increase from 7.0 million in 2018 but a large increase from 6.4 million in 2017 and 5.7–5.8 million annually in the period 2009–2012. In 2020, the COVID-19 pandemic has already had a negative impact on access to TB diagnosis and treatment and will continue beyond 2021.
A Point-of-care (POC) test that readily detects active TB would reduce diagnostic delays, interrupt transmission with appropriate therapy, and address many of the current gaps in global TB control. And although POC diagnostic devices do exist, incidentally, background interference is one of the most critical issues in developing sensitive POC assays for TB diagnosis, as the analyte concentration is low in a majority of the population.
Herein, a simple and economical method was developed for using immobilized proteinase K (ProK), a protease used to reduce background noise, on paper strips (IPK test strips) to pretreat urine samples for subsequent tuberculosis testing via LAM detection (through ELISA).
Testing and stability of the IPK test strips was first performed to ensure ProK immobilization onto the paper. Further testing was done to verify detection of tuberculosis on previously analyzed archived clinical urine samples with known tuberculosis and HIV status.
The results of IPK treated samples were not only consistent with other pretreatment strategies, but also much faster. Thus, the urine pre-treatment strips developed here have the potential to reach adult and pediatric patients regardless of HIV status or geographic location, not only to facilitate global TB control but also improve assay performance and ultimately treatment outcomes.
By incorporating the pretreatment into a ready-to-use paper test strip, this paper-based method is a simplified, rapid, shelf-stable and cost-effective tool that can enhance our current surveillance methods by increasing sensitivity and functionality, thus presenting an advantage for point-of-care testing and detection globally.
- Ready-to-use, room temperature, shelf-stable testing strips
- Advantageous for remote areas and developing countries
- Cost-effective enhanced pretreatment of sample
- Does not require instrumentation or training laboratory personnel
- Comparable sensitivity to standard testing
- Point-of-care detection of active tuberculosis from urine or serum
- Immobilization strategy can be used to decrease background noise in other POC tests