NEW YORK (GenomeWeb) – Canadian molecular diagnostics firm Qvella is developing a sepsis diagnostic that uses differences in surface charge and mobility to pluck sepsis-causing pathogens from blood samples.
The firm announced yesterday that it had raised $20 million in Series A financing to further develop its products and expand its team.
In a prototype of the cartridge-based technique — called Field Activated Sample Treatment, or FAST — cells are electrically treated and lysed, then pathogen nucleic acids are subjected to an array-based multiplex RT-PCR, Tino Alavie, co-founder and CEO of Qvella, told GenomeWeb in an interview.
The cartridge is called the FAST ID card, which will accept whole blood samples. The card is placed into a larger system that prompts the user through the loading sequence and then performs all the necessary steps, from cell isolation, lysis, treatment, and thermal cycling to detection and eventual data upload.
Qvella is currently in pilot clinical trials of this prototype platform, Alavie said.
The firm was founded in 2009, and has been developing its core technology entirely in house. The five founding members of the Toronto-based firm have doctoral level training in various scientific fields, Alavie noted.
Only a few colony-forming units per milliliter of blood are needed to cause a dangerous bloodstream infection. But the challenge is that pathogenic cells are often a similar diameter as cells in human blood, so in a milliliter sample one might have five or six pathogenic cells in a background of billions of RBCs and PBMCs, as well as cell-free DNA, Alavie said.
"If you lyse everything, you end up with a soup, and in pulling your target DNA out of that you will ultimately end up with some background," he said.
Currently, standard sepsis detection techniques require culturing of bacteria from blood, although some recent molecular methods speed the process by testing positive blood cultures against a panel of possible pathogens.
Other commercial technologies targeting scarce organisms often require purification and extraction techniques, but the Qvella device rids the sample of unwanted background by leveraging its proprietary sample treatment technology, which extracts bacterial and fungal cells from an abundance of human blood cells.
"Instead of lysing everything together and then relying on a molecular cleansing approach, we get rid of blood cells up front," Alavie said, adding, "Our integrated cartridge enables us to wash the volume while we hold the pathogenic cells."
In the pilot clinical trial, the prototype of the Qvella platform takes less than an hour to perform the assay, Alavie said.
The firm has previously published in PLoS One on a flow-through method for lysis of Gram-negative and Gram-positive bacteria, as well as Mycobacterium species.
Interestingly, fungal cells have worked equally as well as bacterial cells using the system, even though they tend to require more stringent extraction steps such as bead beating with other approaches.
Using the FAST method, there are no reagents required to lyse the cells, so possible deleterious effects on PCR are eliminated. The pathogen genetic material is also concentrated, which can reduce background.
"Your PCR becomes faster, you can use friendlier enzymes, and this is a compounding effect from cleaning the sample up front," Alavie said.
The initial inspiration for the technology actually came serendipitously from reading an article about the bacteria that form dental plaque. With his electrophysics background, Alavie noted that these bacteria were described as adhering tightly to enamel in part because they are electrically charged, with toothpaste balancing that charge to help release plaque.
The group then started doing literature searches, which inspired them to keep investigating.
"We all have a very strong scientific background — we've built products before, we've worked with each other in different companies, so we self-funded our work for three years — once we solved the science, we started doing more and more development," Alavie said.
The firm has not yet disclosed any timelines for the system at this point, but data from the pilot clinical trial will likely be presented in the first half of next year.