Even with demand for COVID-19 testing waning in recent months, the need for faster and more accurate diagnostic tests remains while the pandemic continues, and new variants evolve. Against this backdrop, Canadian diagnostic company MedMira sees its rapid vertical flow (RVF) tests challenging traditional lateral flow assays in both speed and accuracy for a variety of infectious viruses, including SARS-CoV-2. The company, which was established in 1994, has developed RVF-based in vitro diagnostics that are intended to compete with lateral flow testing. Instead of relying on a capillary reaction to move fluid from side to side — hence lateral flow — RVF uses gravity to move fluid down in "almost a free fall" to "make the reaction time much faster," MedMira CEO Hermes Chan said. It's similar to lateral flow, but "upside down." While the company does offer COVID-19 tests, its focus has long been on screening tests for a broader range of infectious diseases — namely, sexually transmitted infections. Its Reveal G4 test for HIV has received premarket approval from the US Food and Drug Administration and is available in the US. In 2017, the Nova Scotia-based firm received CE marking for its Multiplo TP/HIV rapid test for the simultaneous screening of HIV and Treponema pallidum, which causes syphilis. And earlier this year, MedMira nabbed CE marking for two additional tests: an antibody-based syphilis test for T. pallidum, Reveal TP, and its Multiplo Complete Syphilis (TP/nTP) Antibody Test for both treponemal and non-treponemal antibodies. Regardless of the disease, the company's technology works the same way but relies on different antigens or antibodies depending on what's being detected. A drop of the sample is applied to a test cartridge that has a reactive membrane, and if the specimen contains the target antibodies or antigens, they are captured on the membrane. Once a detection reagent is applied, they can be seen on the membrane, and a test line or dot will appear on the cartridge readout window — a control line without a red dot or another red line indicates a negative result, while a control line with a red dot or another red line indicates a positive result. The entire process takes less than three minutes. The tests also have shown high sensitivity. A study from 2020 in the Journal of Clinical Virology evaluated the Reveal G4 test for HIV and found the test's sensitivity was 100 percent for HIV-1 and 98 percent for HIV-2.

Multiplo® tests

Fig1. Multiplo® tests for hepatitis B and C, HIV-1/2 and syphilis.

A separate study from 2016 published in Sexually Transmitted Diseases looked at the Multiplo Rapid TP/HIV antibody test and saw sensitivity of 94 percent for the HIV component and sensitivity of 81 percent for the T. pallidum component. In addition to its STI tests, MedMira has multiple COVID-19 tests available, both antigen-based for the rapid detection of an active infection and antibody-based to determine a past infection. The company offers its Vyra CoV2 antigen test for SARS-CoV-2 and its Vyra CoV2Flu multiplex antigen test for SARS-CoV-2 and influenza A/B. It also offers the RevealCOVID-19 Plus test to detect total SARS-CoV-2 antibodies and the RevealCOVID-19 NabY Anti-RBD Antibody test for SARS-CoV-2 neutralizing antibodies. The Vyra antigen tests have been submitted to the FDA for Emergency Use Authorization and to Health Canada, Chan said, while the total antibody test received CE marking in February. The firm is also awaiting CE marking for its SARS-CoV-2 NabY test and the two Vyra antigen tests. The tests don't require an instrument, just the single-use cartridge, which costs between $5 and $15. Additionally, the company received a US patent earlier this month for its MiroQ instrument, which combines the RVF technology with surface-enhanced Raman spectroscopy (SERS) to provide both qualitative and quantitative results. SERS has been used in diagnostic development for decades and requires no staining or labeling of target molecules, detecting the molecules instead by reading changes in the way their vibrations scatter light. Multiple research teams have used SERS for SARS-CoV-2 tests, including a team from Johns Hopkins University that has used SERS, in combination with nanotechnology and machine learning, to develop a platform to differentiate between SARS-CoV-2 and other diseases. Researchers from Chung-Ang University in South Korea, meantime, have paired SERS with PCR and nanodimples to detect the virus. The benefit of combining SERS with RVF is that it can turn simple qualitative tests into quantitative tests to determine "how positive is positive." MedMira sees users relying on the company's traditional RVF tests as rapid screening methods and then transitioning to the MiroQ instrument for further diagnosis and treatment monitoring. The instrument was adapted to read the firm's RVF test cartridges, allowing users to take an RVF test and place it in the reader, Chan said. Right now, the existing MiroQ systems are laboratory-based and unwieldy, but the second phase of development — the one MedMira is in right now — is focused on developing a desktop version of the instrument that would be the size of an iPad," . The company hasn't settled on a price for the platform yet, but it would likely be distributed either through a lease-to-own framework or for a low cost but with the promise to purchase a certain number of test cartridges. Most of the firm's currently available tests are being used at doctors' offices or screening outlets, Chan said, but once the MiroQ is available the market could expand to include specialists' offices for a confirmatory diagnosis and treatment monitoring, as well as largescale screening programs. In the past two years, MedMira has sold nearly a million tests, he noted. In light of the FDA's reclassification of certain hepatitis C diagnostic tests in November, the firm has made a presubmission for its own hepatitis C antibody test. It is also working to expand the reach of its HIV/syphilis combination test and has completed clinical trials in Canada for regulatory approval there. Despite adapting to the needs of the COVID-19 pandemic with some of its tests, MedMira's focus remains on further developing STI products.

Source: 360DX