B.1.617 is definitely more transmissible
- Among the key voices of the World Health Organization (WHO),Soumya Swaminathan, with her clarity of thought, articulation and deep awareness of the Indian context, has emerged as a reliable voice amid the COVID-19 pandemic maelstrom. In an online interview, she provides detailed responses to a range of topics that are simmering, resolves some doubts, and advocates strategies to adopt gainfully.
- B.1.617 is definitely more transmissible, one and a half to two times more than the original strain. In fact, it’s even more transmissible than the B.1.1.7, which was identified in the U.K., and which had at one point become the predominant strain in India. But it’s now being replaced by the B 1.617.
- So far, the WHO has four variants of concern, the latest being the B.1.617, now found in about 50 countries worldwide. Now, there are sub-lineages that have been described, the B.1.617 itself has been divided into different strains — each of them has a slightly different set of mutations, with slightly different properties.
- The B.1.617 variant of SARS-CoV-2 carries two mutations, E484Q and L452R. Both are separately found in many other coronavirus variants, but they have been reported together for the first time in India.
- The two mutations are found in the virus’s spike protein. The spike protein helps the virus to bind itself to the human cell’s receptors and gain entry into a host cell.
- The E484Q mutation is similar to E484K, a mutation found in the United Kingdom (lineage B.1.1.7) and South Africa (B.1.351) variants of the coronavirus.
- The L452R mutation has been found in fast-spreading variants in California (B.1.427 and B.1.429). It can increase the binding power of spike proteins with ACE2 receptors on human cells, making it more transmissible. L452R can also potentially enhance viral replication.
- Together, E484Q and L452R are more infectious and can evade antibodies.
How do variants of a virus emerge and why?
- Variants of a virus have one or more mutations that differentiate them from the other variants that are in circulation. While most mutations are deleterious for the virus, some make it easier for the virus to survive.
- Essentially, the goal of the virus is to reach a stage where it can cohabitate with humans because it needs a host to survive. This means, any virus is likely to become less severe as it keeps evolving, but in this process, it can attain some mutations that may be able to escape the body’s immune response or become more transmissible.
- The SARS-CoV-2 virus is evolving fast because of the scale at which it has infected people around the world. High levels of circulation mean it is easier for the virus to change as it is able to replicate faster.
- The B.1.617 variant of the virus has two mutations referred to as E484Q and L452R. Both are separately found in many other coronavirus variants, but they have been reported together for the first time in India.
- The L452R mutation has been found in some other VOIs such as B.1.427/ B.1.429, which are believed to be more transmissible and may be able to override neutralizing antibodies. The WHO has said that laboratory studies suggest that samples from individuals who had natural infection may have reduced neutralization against variants that have the E484Q mutation.