Evolution of dengue in India

Subject : Science and technology

Concept :

A team of researchers from the Indian Institute of Science has analysed the evolution and diversity of dengue virus in India by studying 184 whole-genome dengue sequences and 408 E gene sequences spanning over 60 years.
Researchers have found that the cross-protection offered by the first infection with any of the four dengue serotypes starts to wane after two to three years, and the virus that is similar to the serotype that caused the first infection has a greater ability to cause severe disease than the other serotypes.
This is because while the antibodies are not able to neutralise the virus belonging to different serotypes, the virus is better able to bind to the antibodies leading to higher cell infection and thus enhanced severity and viral load.
This is called the antibody-dependent enhancement mediated by cross-reactive antibodies.
The dominant immune selection pressure has led to the emergence of a unique Indian dengue lineage (DENV-4-Id) belonging to serotype 4(DENV-4).
They identified a unique Indian dengue lineage (DENV-4-Id) belonging to serotype 4 (DENV-4) that is dominant in South India, and about 50% of infections in South India are due to this lineage.
The researchers also found that the evolution of the viruses across serotypes has implications in vaccine efficacy as the current Indian lineages are highly divergent from those used in all major vaccines.

For further notes on Dengue, refer – https://optimizeias.com/dengue/