Charité and Vivantes expand testing
A new testing strategy introduced by Charité – Universitätsmedizin Berlin and Vivantes – Netzwerk für Gesundheit GmbH will see all positive SARS-CoV-2 samples undergo testing for the UK and South African variants. Testing currently takes place at Charité’s Institute of Virology but will shortly move to Labor Berlin, the joint subsidiary of Charité and Vivantes. The aim of the new, supplementary checks is to continually monitor the incidence of SARS-CoV-2 mutations in samples processed by Labor Berlin.
Currently, the focus of testing is on the B.1.1.7 variant, which is dominant in England, and the B.1.351 variant, which was first detected in South Africa. The mutations common to both of these variants include changes in the main surface protein which the virus uses to bind to the human target receptor. This could make it easier for the virus to enter host cells, which in turn could render it more infectious.
The additional testing Labor Berlin and Charité have put in place for all positive samples will be launched later this week.
The aim is to establish the proportion of samples with known mutations within a specific test cohort. This information can be used to establish whether certain variants spread more effectively than others. The additional testing steps are performed for monitoring purposes and only take place once the original PCR test results have been obtained and reported.
Labor Berlin is also preparing to carry out genome sequencing on positive samples in order to confirm the presence of other mutations. This type of testing, which currently takes place at Charité’s Institute of Virology, will ensure that any other relevant changes affecting the coronavirus are detected early.
Confirmation of virus variants
To establish whether a sample contains either the UK or South African variant, it is subjected to a series of PCR (polymerase chain reaction) tests. The first test, which checks whether the sample contains sections of SARS-CoV-2 genetic code, determines whether the person from whom the sample was collected has the infection. Positive samples are then subjected to a further PCR test which checks whether they contain the mutation N501Y, a ‘marker mutation’ which is common to the UK, South African and Brazilian variants. Samples which test positive for the N501Y mutation are then tested for further marker mutations, to enable scientists to distinguish between the various variants. Individual patients are not informed of the results of this variant testing.
For quality control and research purposes, a selection of positive samples also undergo genetic sequencing. This process determines the precise sequence of genetic information contained within the virus, enabling researchers to read the order of the genome’s building blocks. All genome sequence data are stored in the Institute of Virology’s database and made available to researchers. The same data are also transmitted to the Robert Koch Institute and made available to the international GISAID database.
Charité – Universitätsmedizin Berlin
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