Variants

SARS-CoV-2 is an RNA virus. However, the enzyme responsible for replication of the virus genome to create new viral particles, polymerase, commits many errors. These mutations may persist if they endow the virus with an advantage. When a certain number of mutations accumulate, the virus becomes a variant, meaning a virus which is very close […]

The emergence of Variants of Concern (VOCs) with increased transmissibility and capable of escaping immunity has called into question the efficacy of current vaccines. Several studies have shown that these variants’ new capacities involve mutations in the spike protein that controls entry of the virus into cells. The Omicron variant, recently identified in South Africa, […]

The COVID-19 pandemic is still not over and SARS-CoV-2 continues to evolve. Firstly detected in November 2021 in Botswana and in South Africa, the Omicron (B.1.1.529) variant of concern (VOC) is supplanting the Delta variant and becoming dominant. Its doubling time may be between 1.2 and 3.6 days in an immunized population. It carries more […]

Innate antiviral immune responses, located upstream to antibody and cellular responses, impose selection pressure during SARS-CoV-2 infection and directly impact the severity of COVID-19. In infected cells, the RIG-I and MDA-5 pathways detect the presence of viral RNA and activate certain defence mechanisms. But some data suggests that SARS-CoV-2 could be capable of blocking these […]

The enzyme involved in the SARS-CoV-2 genome mechanism of creating new virions makes random errors during this replication process, leading to mutations. When a mutation gives the virus an advantage, such as improved transmission effectiveness, it persists. The more a virus is transmitted, the more it reproduces, and the greater the risk of mutations. When […]

Even though the Delta (Indian) variant remains largely dominant in France, the first cases of the Omicron variant have already been detected. It has become dominant in South Africa and has reached numerous other countries. It carries multiple mutations, many more than other variants. Its spike viral protein, which enables entry of the virus into […]

Coronaviruses contain an RNA genome. The enzymes involved in their replication make more errors than those in DNA viruses. For this reason, the more an RNA virus spreads, i.e. multiplies, the more likely it is that variants will emerge. The mutations that have the greatest effect on the virus are those in the spike (S) […]

The 2nd year of the COVID-19 pandemic has been marked by Variants of Concern (VOCs) that have caused more serious epidemic waves than occurred during the 1st year. These include the Alpha (UK), Beta (South African), Delta (Indian) and Gamma (Brazilian) variants, which are more contagious and are able to evade immune responses to a […]