Since the SARS-CoV-2 virus caused a global pandemic in 2020, the virus has been constantly mutating, giving rise to many different variants that have had a huge impact on human health and socio-economically. Of these, those of greatest concern are those variants that are more contagious, more immune evasion, or more pathogenic, as they may lead to more infections, hospitalizations, and deaths, as well as reduced effectiveness of vaccines and **.
In 2021, a variant called delta spread rapidly around the world, becoming the dominant SARS-CoV-2 variant at the time. The delta variant is characterized by being more contagious and more immune evasion, which allows it to infect those who have been vaccinated or have been infected with other variants. The Delta variant is also thought to be more likely to cause severe COVID-19 illness than previous variants, especially for those who are unvaccinated or have underlying medical conditions.
In 2022, another variant called Omicron emerged, which quickly replaced the Delta variant globally as the most dominant SARS-CoV-2 variant. The omicron variant is characterized by being more contagious and more immune evasion, which allows it to infect those who have been vaccinated or have been infected with other variants. However, the omicron variant appears to be more likely to cause mild COVID-19 disease than the delta variant, which may have something to do with the way it enters human cells.
The SARS-CoV-2 virus typically enters human cells through two different surface proteins: ACE2 and TMPrss2. ACE2 is a receptor present on many human cells that binds to the spike protein of the virus, allowing the virus to enter the cell. TMPrsS2 is an enzyme found on certain human cells that cleaves the spike protein of the virus, allowing the virus to enter the cell. When the virus mutates into the Omicron type, it begins to preferentially choose ACE2 to enter cells over TMPrsS2. This makes the virus more transmissible but less severe, which is why omicron disease features are milder.
Recently, however, researchers at Ohio State University discovered a new coronavirus variant that may be more dangerous than Omicron, and it was named BA2.86。This variant is derived from the original ba2 The first notable line of virus produced in the Omicron family, which first appeared in August 2023 and later mutated to JN1. It has become the most dominant SARS-CoV-2 variant in the world. This variant is more susceptible to infecting certain lung cells than any previous Omicron variant, which can lead to more severe COVID-19 disease.
Using a method of cell culture, the researchers compared BA2.The 86 variant is associated with other variants (including delta, xbb, and ba.).2) Infectivity and fusion activity against human lung epithelial cells. They found, ba2.The 86 variant is more susceptible than other variants to infect and fuse a type of lung cell called calu-3. These cells are located in the lower part of the lung and are lined with the TMPrss2 surface protein, which means BA2.The 86 variant can utilize TMPSS2 to enter cells instead of ACE2. This is similar to the characteristics of earlier SARS-CoV-2 variants, which are also able to use TMPSS2 to enter cells, leading to more severe disease.
Shan-Lu Liu, senior author of the study, said: "....Compared to all omicron variants, BA2.86 appears to increase infectivity to human lung epithelial cells, so this is a bit of a concern. Consistent with infectivity, its fusion activity with human lung epithelial cells is also enhanced. This raises potential concerns about whether the virus is more pathogenic than the recent omicron variant. ”
The researchers also found that ba2.The 86 variant has a weaker immune evasion than the XBB variant, meaning it is less likely to infect those who have been vaccinated or have already been infected with other variants. This also explains why ba2.86 variants in it transferred to JN1 Before, ba2.The 86 variant did not cause a massive epidemic worldwide. This may be related to its lower contagiousness, as well as people's adherence to vaccines and prevention and control measures. However, jnThe 1 variant, however, began to spread rapidly in many countries and regions at the end of 2023 and became a major threat in early 2024. jn.1 variant is from ba2.The 86 variant was further mutated and had 6 new mutations in the spike protein, 3 of which were located in the key receptor-binding domain (RBD). These mutations make jnThe 1 variant is more contagious and has a greater ability to evade immunity, which allows it to infect those who have been vaccinated or have been infected with other variants. jn.The 1 variant is also considered to be better than BA2.The 86 variant is more likely to cause severe COVID-19 illness, especially for those who are unvaccinated or have underlying medical conditions.
In response to jn1 The threat of variants, countries have stepped up the development and updating of vaccines, as well as the implementation and monitoring of prevention and control measures. At the same time, scientists are constantly monitoring and analyzing jn1 Characteristics and effects of variants, as well as new variants that may emerge. Currently, the World Health Organization has put jnThe 1 variant is listed as a "variant of concern currently circulating" and calls on countries to remain vigilant and cooperate in the fight against the mutation of the coronavirus. The growth rate of the coronavirus variant is staggering