Many groups around the world are trying to develop vaccines that protect against a wide range of coronaviruses and prevent another pandemic. These efforts are now boosted by the discovery that some healthcare professionals had existing immunity to the SARS-CoV-2 virus during the first wave of the pandemic.
In the first half of 2020, about 700 healthcare professionals in the UK were tested weekly as part of a crowdfunding survey. Called the COVID sortium.. Most of these people who wear protective equipment have never tested positive for covid-19 in the PCR test or developed covid-19. antibody – A protein that binds to the outside of the virus and prevents cells from infecting.
However, a closer look by Leo Swadling and Mala Maini of University College London and their colleagues found that some people who tested negative contained proteins associated with covid-19 infection in their blood. T cell response For SARS-CoV-2 virus. T cells are part of the immune system. These people seem to have what Swadling calls an “absorbent infection.” There, a strong early T cell response allowed the virus to be eradicated very quickly.
Virus-infected cells warn by displaying viral proteins on their surface. T cells are immune cells that learn to recognize these proteins and destroy infected cells. Importantly, antibodies can only target proteins outside the virus, but T cells can learn to recognize viral proteins.
When the team examined early blood samples from people infected with miscarriage, some could recognize the protein that the virus uses to replicate itself within the infection, even before exposure to SARS-CoV-2. It turned out that there were T cells. cell.
The most likely explanation is that these people were often exposed to the pre-existing human coronavirus, which causes about 10 percent of the common cold, says Maini. “We are unaware of the historical infections of these individuals, so we are not sure where the T cells come from,” she says.
Prevention of another pandemic
The proteins involved in viral replication are very similar in SARS-CoV-2 and other human and animal coronaviruses. This means that if we can develop a vaccine that elicits a strong T cell response to these proteins, we need to protect them from a very wide range of coronaviruses. – So-called universal or pancoronavirus vaccine. One way to do this is to add the mRNA that encodes these proteins to. mRNA vaccine Targets the virus’s external peplomer.
Adding additional ingredients to the next-generation coronavirus vaccine may protect against both new variants that may evolve and animal coronaviruses that can jump into humans and cause new pandemics. Yes, says Swadling. “There is a strong rationale for adding these proteins along with the spike proteins,” he says.
Olga Pleguezuelos of the UK-based company SEEK states that many groups are already trying to develop a coronavirus vaccine that provides broader protection. Her team has already created such a vaccine based on the most conserved portion of the coronavirus protein. “Before another member of these members it’s only a matter of time [of the coronavirus family] It causes epidemics or pandemics, “she says. “When we become infectious and deadly like MERS, we face serious problems.”
However, it is not clear how effective a vaccine that produces only a T cell response is, says Maini. Most vaccines work by stimulating an antibody response, but many also produce a T cell response.
Many groups have developed universal influenza vaccines based on the induction of T cell responses, but so far they have not proven to be very effective. Other teams are instead focusing on obtaining antibodies that target the non-mutated portion of the viral protein outside the influenza virus. However, this does not work with the coronavirus, says Peter Parase of Mount Sinai School of Medicine in New York. “They just don’t have a preserved area.”
Journal reference: Nature, DOI: 10.1038 / s41586-021-04186-8
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Some people are naturally resistant to covid-19, and the discovery may lead to a universal vaccine against multiple coronaviruses.
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