PCR assays are being developed to better identify challenging mutations

PCR assays are being developed to better identify challenging mutations

From now on, in the event of a positive PCR test, the biologists will try to determine the presence of one or more of the three main variants selected by Public Health France. – Pascal Bocard – Casabianca / Agence France-Presse

  • Rather than looking for variants when the PCR test is positive, Public Health France recommends focusing on the mutations of most concern.
  • Thus, the health agency selected the E484K, E484Q and L452R mutations, associated with a possible increase in virus transmissibility or the potential for immune escape, that is, higher infection rate and risk of vaccine resistance.
  • Objective: To improve monitoring by identifying the possibility of the emergence of new variants and mutations and preventing their spread in the region.

It’s a sunny, warm and rustic vaccination against Covid that opens
For teens this Tuesday. But there is no way to reduce the pressure in the face
The coronavirus and its variants – always contagious – appear over the course of the months. To avoid gaps in the racket, a French triage strategy is being developed.

In the event of a positive PCR test, from now on, variants will not be searched for, but for “the three mutations E484K, E484Q and L452R”, Public Health France reported in its latest epidemiological publication. What will change? 20 minutes Explain you.

Increased alertness in the light of the delta variable

English, Hindi, Brazilian, or South African, or rather Alpha, Delta, Gamma and Beta: today it is difficult to see clearly among the many variants. On the other hand, what is certain is that so far in France, the alpha variant, which appeared in the UK, is still in the majority: [de ce] The variant is still very common and accounts for 74.6% according to the analysis of the survey results in the twenty-second week “that is, the week from May 31 to June 6, which indicates
Public Health France.

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The delta variant, which appeared in India, is responsible for a new increase in pollution with the UK. UK health authorities say:
60% more contagious than the alpha variant. It is less prevalent in France, but Public Health France notes that “the recent increase in [sa] detection in serial samples.” Health Minister Olivier Veran said on Tuesday that it represents “between 2 and 4% of positive cases” of Covid-19, or “50 to 150 new diagnoses” per day. In addition, “the emergence of clusters with An original transmission of this species indicates that such transmission began in France, which should lead to maximum vigilance”, emphasizes the French public health.

To date, positive PCR tests have been examined for alpha, beta, and gamma variants. But the spread of variables prompted France to adjust its screening strategy.

Find mutations that interest you

From now on, “screening is evolving towards looking for interesting mutations,” the health service explains. The E484K, E484Q, and L452R mutations were selected because they are associated with a possible increased (L452R) susceptibility to immune transmissibility or escape (L452R, E484K, and E484Q), hence the need to monitor them in particular. ” In short, these are the mutations that can lead to the emergence of more infectious and vaccine-resistant strains. Improving this strategy depends on the use of new screening groups by laboratories. “, defines Public Health France. Practically speaking, “only reagents change and machines are the same,” Dr. Lionel Barrand, president of the Federation of Young Medical Biologists. However, we need to run tests on these new reagents, which reveal mutations different from those detected so far.”

Anders: “This is not a new approach, because we were already looking for mutations. Except that in the conclusions we were interested in the ‘geographical’ name of the variant, which didn’t make sense because we can have many different variants in the same country,” Dr. Barrand. For example, an alpha variant was found with and without the E484K mutation.” Moreover: “We could not find more. We especially had the English version 4 that came back with an Indian boom, which Dr. François Blanchot, President of the Syndicate of Biologists. We are aware that this virus adapts to the audience it encounters by mutating. It therefore makes sense to modify the surveillance strategy to target key mutations.”

Follow the evolution of the virus on Earth

For the biologists responsible for these more in-depth tests: “What changes are the goals: We will focus on these three mutations, which are of medical importance today. And maybe in a few months, we will be asked to look for new ones,” explains Dr. Barrand outside.

With this change “it’s all about following the evolution of virus mutations on French soil”, the biologist continues, thanks to a new and more efficient sequencing strategy – research. These two complementary technologies act like two networks whose network is not the same size. “By scanning, we find exactly what we’re looking for: the variants that are currently circulating. Sequencing allows him to identify mutations that are spreading, but also to find new ones. And if new ones are found, sequencing will allow us to
Define a new variable of interest d. François Blanchecott added: “This result results in the mutation being encoded with three numbers and two letters, just like the E484K mutation.”

“The scan is good, but you need to know what to do”

What are the tangible effects of a more detailed screening strategy? The basic tool of epidemiological surveillance, Diptych, can improve the strategy of controlling the spread of the virus. Dr. says. Baran. Where there is a mutation that we absolutely wish to prevent from spreading, due to the high risk of infection and the increased escape of the vaccine, it is necessary for people who test positive for this mutation to organize a differentiated management using the more stringent isolation strategy described by Dr. parand it. Because screening is a good thing but you need to know what to do. However, at the moment, there is no really definite strategy in this matter.”

But already, “if we find out that a population is highly evolving, we’ll look around the specific patient for all those who are going to show that particular mutation,” emphasizes Dr. Blanchecote. The disclosure remains crucial, despite the improvement in the health situation in France, especially on the eve of the summer holidays. The medical biologist recalls: “We have reached the level of vaccination, at a time when it may be difficult to convince the French who have not yet been vaccinated. By identifying new manifestations of mutations, we can work by targeting vaccination to populations close to groups, such as what happened in Bordeaux? To further protect them in the event of a more contagious or immunization-resistant mutation.”

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