Testing: building a rapid coronavirus test

24 March 2020

Interview with 

Annelyse Duvoix, Mologic

PREGNANCY_TEST

A pregnancy test.

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Some of the coronavirus antigens are going to companies working on better tests for the coronavirus. At the moment we’re testing for it by looking for the genetic code of the virus, and that’s a relatively slow process. But Bedfordshire-based Mologic have just received a million pound grant from the UK government to develop a rapid test that should work within minutes. They’re a company that formed out of the team that invented the modern pregnancy test. And when Phil Sansom spoke to their scientist Annelyse Duvoix, she explained that the finished coronavirus test should be very similar...

Annelyse - It's basically going to look like a pregnancy test, except we do not use urine as our sample.

Phil - So a little bit of plastic that you can just spit on or something. And then it could tell you whether you might have the coronavirus?

Annelyse - Yeah, something like that. So we might use blood samples from your finger like you would do if you had diabetes.

Phil - Like a pregnancy test, it should be able to detect the presence of the coronavirus by showing up a visible line on the test. They're going to do this by using antibodies, parts of people's immune systems that recognise invaders, and these ones are going to recognise the outer coating of the coronavirus. Usually this kind of test actually involves a pair of antibodies.

Annelyse - So we usually need two. We've procured some antibodies, commercial antibodies. We are very early on and we're just going to start testing those.

Phil - One antibody is stuck onto the test in a line at the far end. The second antibody is linked to a coloured material. They use tiny, tiny particles of gold.

Annelyse - We usually use gold cause it's large and it's red.

Phil - And that's at the opposite end of the test. When you add the saliva or blood to the test, it dissolves and takes up the antibody with the gold into a suspension. If the blood or the saliva had virus in it, the antibody is going to stick to the virus. Then all this liquid soaks up through the test carrying the virus and the antibody with it. When it reaches the opposite end of the test, the second set of antibodies, the ones glued into a line there, they grab any of the virus that's in there and because the antibody with the colour was already stuck to those virus particles, that gold comes out and is visible there as a line. How long does the test take between a sample of blood or whatever and actually revealing whether or not there's the coronavirus present?

Annelyse - Usually we go for 10 minutes.

Phil - How long does that compare to the test people are using at the moment?

Annelyse - Some of the tests you need to send a sample to the lab, you will get an answer within the day, I would say, but nowhere near 10 minutes.

Phil - So this is a fraction of the time and presumably a fraction of the cost once it's actually made, right?

Annelyse - Yes.

Phil - Okay, million dollar question: how long do you think it's going to take?

Annelyse - We don't know. It could work very easily and simply. However, we could also find that the antibodies that we've got don't like to work together, or that we detect more than the COVID-19 virus and we need to go back and find the antibodies that don't recognise other viruses; but if everything works and we are lucky we could have a first prototype, early prototype, within two weeks to a month.

Phil - Murphy's law, things very often go wrong...

Annelyse - Of course.

Phil - ...it may take a few more months, yes?

Annelyse - Yeah.

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