Packaging isothermal PCR reagents in blisters and using lateral flow detection, researchers at Boston University hope to develop a low-cost, disposable assay for Bordetella pertussis, the causative agent of whooping cough.
The project recently received two years of funding from the National Institute of Allergy and Infectious Diseases, totaling about $120,000.
Much of the funding will support the postdoctoral researcher spearheading the project, Jacqueline Linnes, a bioengineer in the lab of Catherine Klapperich at BU. Linnes' previous work has also focused on improving health in low-resource settings, and she is a member of the New York Academy of Sciences community Scientists Without Borders.
According to Linnes, the proposed device will have multiple modules and a slider to move samples through nucleic acid extraction, amplification, and detection steps.
A clinical specimen will be applied to the first module and pushed through to the second, thus filtering and drying it. Isothermal helicase-dependent amplification (HDA) reagents will be released from a blister pack onto the dried sample to amplify pertussis. The reaction will be warmed to 65 °C using a chemical heater similar to a hand warmer, and the resulting amplicons will be detected visually using labeled probes in a lateral flow assay.
Pertussis infection readily responds to antibiotic treatment, but there are currently no fast, inexpensive pertussis tests commercially available. Babies not yet old enough for pertussis vaccination are most vulnerable to infection. However, early symptoms often resemble other respiratory diseases, and thus babies may not receive prompt treatment. Alternatively, lack of a quick and reliable pertussis test means some babies may be given antibiotics without need, accelerating development of antibiotic resistant strains of bacteria.
Blister packaging HDA reagents is not an entirely new idea, but it has yet to be realized in a commercial device.
Linnes said the Klapperich lab had conceptualized this type of packaging in their system for nucleic acid preparation, or SNAP, a microfluidic device powered by a bicycle pump. This was developed in collaboration with the Program for Appropriate Technology in Health, a Seattle-based non-profit global health group that funds scientific innovations. This project was intended for nucleic acid extraction from blood samples in low-resource settings, she said, "but the actual one that ended up being developed, the volumes were too large for a blister pack."
Samuel Sia, a biomedical engineer at Columbia University who was not involved with this project, authored a recent Lab on a Chip review on commercialization of microfluidic point-of-care diagnostic devices. In an email to PCR Insider he said that "there isn't anything commercialized (or close to being commercialized, to my knowledge) using blister-packed reagents of any kind."
ThinXXS, a German microfluidics manufacturer, has previously attempted to commercialize blister packaging for microfluidics. Another German group also recently published results of blister packaging, or miniature stick-packaging, using foil pouches with volumes ranging between 80 and 500 microliters, and a Danish group has improved on-chip storage in blister packs by using gelified PCR reagents in a lab-on-foil technique.
However, using blister packaging in combination with a paper-based lateral flow test appears to be novel.
Linnes said the pertussis test blossomed out of a design for chlamydia and gonorrhea detection, which was a collaboration between the Klapperich lab and BioHelix, which developed the HDA technology. That device was designed to use HDA, but was tabled when BioHelix was acquired by Quidel, according to Linnes. The Klapperich lab has also successfully collaborated with Wave 80 Biosciences in the past.
The pertussis POC project is in its infancy, but Linnes hopes it will ultimately be commercialized. She said the lab "definitely wants it to get out the door and do something useful. I don't know the specifics of that yet, what would happen or where it would go … but certainly translating it to commercial and clinical [applications] is the goal."