Stemnovate creates rapid diagnostic kit for Covid-19 that solves problems of false positives

Stemnovate has released a £10 rapid diagnostic kit for the Covid-19 virus that it says will overcome the challenges of false results in testing.

The biotech company intends to manufacture the kits at Babraham Research Campus and is now seeking support to scale up the operation.

The kits use the gold standard RT-PCR (reverse transcription polymerase chain reaction) method accepted by health authorities around the world.

Stemnovate says it has worked with expert partners, leading virologists and national centres of excellence – including MRC Centre for Virus Research, Scotland and National Physical Laboratory (NPL) – to ensure the kits are “100 per cent accurate”. It has also consulted the regulatory body MHRA to ensure the kits are CE compliant.

Dr Ruchi Sharma told the Cambridge Independent that the company used bioinformatics techniques, along with in silico and laboratory validation to develop the test.

It then carried out molecular test validation using both a laboratory-cultured and patient-derived SARS CoV-2 virus.

It validated the kit against false negatives and positives by testing it, with the aid of the MRC-University of Glasgow Centre for Virus Research against a rhinovirus, which causes the common cold.

Similarly, the kit was also tested with yellow fever virus vaccine strain RNA – another single-stranded RNA virus – to ensure its specificity and accuracy in detecting SARS CoV-2.

“People are not evaluating how much RNA they are getting, so there are a lot of false positives and negatives,” said Dr Sharma.

“There is a huge disparity in the amount of RNA you get in saliva. And there are enzymes that destroy RNA. So the first issue is to find enough RNA in the saliva to have a reliable test.”

As well as RT PCR, the kit supports qPCR, or quantitative PCR, which tells you how much RNA is in the sample.

“There are positive and negative controls in there. The user will know if the reaction has worked and whether there was enough RNA, so that it will not give you any false positives,” said Dr Sharma.

“We are ready to support the testing programmes around the world and invite experts to join our initiative as we continue to innovate while learning more about the variable viral load in field samples such as saliva and nasal swabs, and the problems of collection and handling.”

Stemnovate’s kit also comes with data on the limit of detection, interference and reproducibility.

“Interference is a big problem with testing, because of other colds and viruses,” she noted. “Ours recognises only SARS-CoV-2, and we have proven it.”

It is supplied with a ‘reaction master mix’ to prevent errors in what would otherwise be a multi-step procedure.

“With RT-PCR you have to buy the reagents and nucleotides and then run a reactive test. We have created a mixture that is ready to use,” says Dr Sharma.

“We will start increasing our capability and employ more people as the orders came in. Whatever support we can get from the government will be welcome. Reaching the government has proved to be the hardest thing.”

Stemnovate’s platform also enables further analysis.

“The positive samples can be further sequenced at Stemnovate to understand the viral profile and mutations. There is no concern of human DNA breach and confidentiality with the sequencing as this test only recognises the viral genes,” says Dr Sharma.

Stemnovate is continuing to work on achieving a CE mark for its Covid-19 diagnostic test on a chip , which the Cambridge Independent reported on in July. This nucleic acid testing kit is designed for deployment at businesses, care homes, airports and other key locations.

In the meantime, Dr Sharma said she knew Stemnovate could play a role in easing the current testing bottleneck.

“We are eager to hear from testing laboratories, and from today will start providing our kits to both private and government bodies along with the distributors, regulators and investors,” she said.

Testing labs or investors can contact ruchi.sharma@stemnovate.co.uk.

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