Prior Infections Driving Dengue Virus Evolution in India
Context:
A team led by Dr. Rahul Roy from the Department of Chemical Engineering at the IISc conducted a detailed investigation of the virus diversity and evolutionary dynamics in India based on an analysis of 184 whole-genome dengue sequences and 408 E gene sequences from India spanning more than 60 years. They studied how viruses evolve from their forebears in the presence of serotypes.
Points to ponder:
- Dengue (DENG-gey) fever is a mosquito-borne sickness that occurs worldwide in tropical and subtropical locations. Mild dengue fever is characterized by a high fever and flu-like symptoms. Dengue hemorrhagic fever, often known as severe dengue fever, can result in severe bleeding, a precipitous drop in blood pressure (shock), and death.
- The article highlights a study led by Dr. Rahul Roy of the IISc’s Department of Chemical Engineering that examined the virus diversity and evolutionary dynamics of the dengue virus in India.
cross-protection from dengue virus:
- When a person has been infected with one dengue virus serotype, he or she is protected from reinfection with the same serotype for some time.
- After two to three years, the protective effect of cross-protection against a serotype begins to decrease.
- Antibody-dependent enhancement (ADE) occurs when a person who has previously been infected with one serotype of the dengue virus gets infected with a second serotype. Because the antibodies from the prior infection facilitate the entry of the new virus into cells, ADE can result in more severe illness symptoms.
- Viruses that are related to but not identical to the serotype that caused the first infection have a greater propensity to cause severe disease by exploiting weaker immune responses.
- Due to the immunological selection pressure induced by past infections, a distinct Indian dengue lineage (DENV-4-Id) belonging to serotype 4 has emerged. (DENV-4).
The situation in South India
- South India is dominated by the DENV-4-Id lineage.
- This India-specific lineage is responsible for around 50% of infections in South India.
- According to the experts, the DENV-4-Id lineage will become prominent in North India as well.
- The divergence of envelope gene sequences of circulating dengue viruses in South India shows that all four serotypes are co-evolving.
- In South India, the E gene diverges from the original sequence for all serotypes, but this divergence varies throughout time.
- Virus evolution between serotypes has ramifications for vaccination efficacy.
Ways to Prevent
- Remove standing water: Because dengue is spread by mosquitos that develop in stagnant water, it is critical to remove any sources of standing water around your home, such as flower pots, buckets, and old tires.
- Apply a mosquito repellent containing DEET, picaridin, IR3535, or lemon eucalyptus oil to exposed skin and clothing, especially during the day.
- Wear protective clothing: To avoid mosquito bites, wear long-sleeved shirts, pants, and socks.
- Use mosquito nets: If you sleep during the day when mosquitoes are most active, use mosquito netting over your bed.
