Delhi reports first case of BA.2.12 strain
- The national capital has reported the BA.2.12 variant of the COVID-19 for the first time, which is more transmissible than the Omicron variant (BA.2) of the virus
- It was spotted during genome sequencing to find the current surge in COVID-19 cases
- The BA.2.12 is a sub lineage of the Omicron variant
- It is not a cause of concern as there are no reports across the world on BA.2.12 causing more severe infections than Omicron, though it is more transmissible
- It causes mild infection like Omicron, but it's evasion of vaccine immunity is a little higher than the Omicron variant.
- It becomes important to know how these Omicron sub-lineages were created and what makes them more contagious than the original variant.
- Every living organism is run by a predefined set of genes that ‘instruct’ cells how to build proteins.
- Understanding the sequence of genes helps in cracking the code to the organism and how it functions.
- The genetic material of the coronavirus is ribonucleic acid (RNA) strands.
- Each virus has about 26,000 to 32,000 bases or RNA “letters” in its length.
- These letters -A, C, U and G stand for adenine, cytosine, uracil and guanine, nitrogen-containing biological molecules that are the fundamental units of the genetic code.
- The arrangement of A, C, U and G in the genetic code determines what proteins the organism has.
- When a virus multiplies inside the cells of a living organism, it creates copies of the RNA.
- However, the process it uses to make these copies often introduces ‘typos’.
- These errors are called genetic mutations.
- Mutations that do not help the survival of the virus eventually get eliminated, while others keep getting copied in the next generation of the virus.
- The Omicron variant diverged into two lineages- BA.1 and BA.2 and the latter predominated the spread across the world.
- Now these lineages are evolving further.
- While BA.2.12 only has an additional mutation called S704L on its spike protein, the BA.2.12.1 has additional spike protein mutations called S704L and L452Q.
- Spike proteins are the protrusions seen on the outer surface of the novel coronavirus.
- Mutations in the L452 position of the spike protein which is part of the receptor binding domain (RBD) have been previously reported in a number of other variants, including Delta, Epsilon and Lambda.
- The RBD is a key part of the coronavirus, located on its ‘spike’ protein that allows it to latch on to the cell’s receptors and gain entry, leading to infection.
- A similar mutation (at the L452 position of the spike protein), L452R, is also seen in Omicron’s BA.4 and BA.5 lineages, and is presently reportedly increasing in numbers in South Africa.
There is no evidence to show that these sublineages increase the disease severity among patients. However, non-pharmaceutical interventions such as wearing masks and avoiding large gatherings in closed spaces are effective in preventing Covid irrespective of the variants.
- Genetic mutation
- Variants of COVID-19