Globally, there are three main variants – UK, South Africa and Brazil – of Sars-Cov-2, the virus that causes Covid-19 infection. A new strain of Sars-Cov-2 has now been found in Brittany on the west coast of France. Eight issues have been linked to the new version that seems difficult to detect with the PCR method.
In an interview, Dr Camille Locht from the Institut Pasteur de Lille tells RFI how anxious the new snoring is and how he can escape detection by a standard reliable method such as the PCR.
How worrying is the new strain of Sars-Cov-2?
From what has been known so far, the strain remains limited in terms of distribution. But the strange thing is, it seems that it is not easy to identify with the current PCR method.
It means that people with this weight could stay under the radar ie they cannot be detected by the standard test methods. So it is difficult to know how many people are involved in the new snoring.
So, even though they may have some symptoms, the negative PCR test will, presumably, mean that they are not infected. We cannot find and follow them. There is no evidence that the new strain is more active or contagious than other strains. That doesn’t mean people are sicker. But all of these are unknown at this time.
What new proofing techniques are needed to detect the new strain?
It would be wise to develop a new PCR strategy to accommodate this particular species. PCR stands for polymerase chain reaction involving the expansion of the virus genome. In this case, Sars-Cov-2 is an RNA virus that is converted back to DNA and then augmented using reagents called primers.
The primers are specific to a particular genome sequence. So if there is a mutation in the sequence corresponding to these primers, the PCR method will not work. Therefore, new PCR methods needed to be developed to address this particular pressure.
Are you surprised that the new strain has now got stealth mode?
It is not surprising. We know that viruses go around. An RNA virus tends to circulate faster than a DNA virus. A real example of an RNA virus is HIV. Fortunately, Sars-Cov-2 is not as highly susceptible to mutations as HIV.
Nonetheless, what we are seeing with the British, South African and Brazilian lines is that there are mutations in the spike protein that increase the infection of the virus. Eventually, there are bound to be other random changes.
Each time in a time there is a mutation in the sequence that corresponds to the primers used in experimental methods. Although this is the first time he has encountered Sars-Cov-2, it was not expected.
It is just a matter of statistics or probability that there will be a mutation of the sequence that makes it unknown to the standard detection methods.
In addition, other mutations can occur anywhere in the genome. Most viruses are silent as they do not change anything in terms of virus biology. Some mutations can affect survival. They can even kill the virus. But there are mutations that are weird because they increase viability, infectivity or could cause problems for the virus to detect.
The PCR method can still be used for the new strain but for that we need to design new primers for the modified strain.