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Variants

Are recombination events at the origin of variants of concern?

Recombination is a transfer of genetic material between two nucleic acid molecules (DNA or RNA). With respect to viruses, it can occur during the replication of the viral genome when an individual is co-infected by 2 strains of the virus. This process may generate a new variant, carrying a part of the genome of the […]

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How the Alpha variant has spread in the UK?

The Alpha (⍺) or UK variant emerged in England at the end of 2020 and spread rapidly throughout the country. By the 19 January 2021, this variant had reached all 4 countries of the UK. Despite travel restrictions, it then became dominant throughout the world. Studies have shown that this variant has higher transmissibility and […]

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The Epsilon variant could be more resistant!

Numerous SARS-CoV-2 variants have appeared over recent months, including the Californian or Epsilon (ε) variant. This new strain emerged at the beginning of 2021 in California, and had been detected in more than 34 countries, including France, by May. The spike surface protein of this variant carries the L452R mutation in the RBD (the region […]

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The different functionalities of the spike in the Alpha and Beat variants

The mutation rate of SARS-CoV-2 is relatively low due to its correcting activity during genome replication. However, its high rate of replication and its high transmissibility lead to the rapid emergence of variants. Amongst those that have emerged, the Alpha (a) or UK variant quickly became dominant. The Beta (b) or South African variant also […]

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Sequencing new strains: the United States is making efforts to catch up

The emergence of new SARS-CoV-2 variants of concern in recent months has highlighted the shortcomings of the United States in terms of monitoring these variants: more than 30 countries sequence more strains than the Americans. The more strains are sequenced, the more it is possible to follow, to understand and to anticipate the emergence of […]

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Will we be protected against future variants?

B lymphocytes are found in active form in the blood to produce antibodies, or in the form of memory B lymphocytes that will be reactivated during a second encounter with the pathogen, thereby giving long-term protection. The antibodies produced by B lymphocytes remained unchanged and determine the configuration of the humoral response, while the memory […]

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Antibodies can neutralise the Delta variant

The Delta (formerly Indian) variant is now present in many countries. It was first identified in India in October 2020 and rapidly became dominant in several regions of the country, then in the UK. The variant seems to be more transmissible than the Alpha (UK) variant. This strain is composed of 3 sub-types presenting different […]

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Certain variants could escape cellular immunity

The anti-SARS-CoV-2 immune response is made up of antibodies, which block viral infection, and the cellular response, which works through cytotoxic lymphocytes (CTLs) recognising and destroying infected cells. This latter function requires viral proteins presented on the surface of cells by the HLA-I (Human Leukocyte Antigen) complex to enable their recognition. Several mutations of SARS-CoV-2 […]

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The Brazilian variant evolved in Manaus

Brazil is one of the countries most severely affected by the health crisis caused by COVID-19 and had registered more than 13 million cases and 300 000 deaths by March 2021. Amazonas, with its capital Manaus, is among the most affected states; two thirds of its inhabitants had been infected by October 2020. But this […]

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The impact of the D614G mutation

SARS-CoV-2 has a genome made up of a single-strand RNA molecule. When it is replicated by the polymerase enzyme to make new virions, copying errors can arise in the sequence. These errors, if they are selectively advantageous, can become dominant. Early in the pandemic, the D614G mutation appeared from the Wuhan strain and quickly became […]

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