Q&A: Antibody test with the 'most sensitive protein detection technology'

Ian Bolland spoke to Kevin Hrusovsky, CEO of Quanterix, which is producing a COVID-19 antibody test, which it claims has the most sensitive protein detection technology on the market, and is backed by 780+ peer-reviewed scientific journals that prove its ability to see HIV, Alzheimer’s, cancer and other diseases earlier via the blood.

What makes this antibody test different from the ones already known to the public? 

Our Simoa quantitative SARS-CoV-2 spike/IgG assay is significantly more sensitive than other assays (1000x) meaning you can pick up the IgG response sooner in the adaptive immune response and/or leverage the sensitivity to detect antibodies in smaller or more complex samples (like dried blood spots or finger pricks). Serological population screening and monitoring is also further enabled by the ultra-sensitivity of this assay which enables a variety of pooling strategies which can increase testing throughout and reduce overall costs. Additionally, the Simoa assays employ a unique chimeric antibody calibrator to report quantitative concentrations of antigen-specific IgG.

How does this test measure immunity? 

The assay is a specific immunoassay that uses SARS-CoV2 spike protein to detect anti-spike antibodies. There is a strong correlation with level of anti-spike IgG antibody and immunity. Quanterix is additionally working with collaborators to further correlate IgG level with specific immunity. 

Give us some insight on the Simoa technology – what’s gone into developing that to ensure it measures the level of immunity accurately?

The Simoa technology has proven to be the most sensitive and highly specific immunoassay technology available, with over 780 peer-reviewed publications across numerous disease categories, including infectious disease, neurology and cardiology among others. Recently, we set a new standard for protein detection by achieving a 100x sensitivity improvement to our already high definition platform. The results, which were published in May in Lab on a Chip, enable a significant increase to the signal-to-background of these assays, further expanding the measurement of a wider range of soluble protein biomarkers. We leveraged this technology with the key assay reagents developed in the lab of Dr. Florain Krammer at Mt. Sinai which have become standard and validated reagents for the detection of the SARS-CoV2 immune response.

How widely available could this test be? Is it something you’re looking to bring to UK and EU markets? 

We already have a significant install base of instruments in the US and EU on which this test could be run. We are in the process of working with additional large testing labs to make the technology more widely available worldwide.

Can you give us an idea of the rate of false positives and false negatives your test produces? 

While the test is currently for research use only, the assay has specificity of 99.2%, and sensitivity of detection of SARS-CoV-2 IgG antibodies >60% in the first week after, >87% during second week, and 100% after two weeks.

Tell us about the conditions it can pick upon associated with COVID-19? 

The antibody test specifically can detect the direct adaptive immune response to COVID-19 antigens. Our initial test is designed to specifically detect anti-spike IgG after someone has been exposed to the virus. We also have the capability of using other COVID-19 antigens such as nucleocapsid, and the S1 and RBD portions of the spike to more fully assess the immune response of not only IgG but also IgM and IgA. This essentially 4x3 plex assay is a high definition high-resolution approach to monitoring the complete COVID-19 immune response.