KANCHI EXCELLENT

India’s First DNA Vaccine for Dengue.

Date: 17-05-2023

Why in News?

Researchers at India’s National Centre for Biological Sciences, in collaboration with nine other institutions in India, Africa, and the US, have developed India’s first and only DNA vaccine candidate for dengue fever.

• In preliminary trials on mice, the candidate generated a robust immune response and improved survival rates after exposure to the disease.

What is DNA Vaccine?

• A DNA vaccine is a type of vaccine that uses a small piece of DNA that codes for a specific antigen (a molecule that triggers an immune response) from a pathogen, such as a virus or bacterium, to stimulate an immune response.
• The DNA is injected directly into the body's cells, where it instructs the cells to produce the antigen.
  • The immune system then recognizes the antigen as foreign and mounts an immune response against it, which helps to develop immunity to the pathogen.
• DNA vaccines are third-generation vaccines.
• The ZyCoV-D is the world's first and India's indigenously developed DNA based vaccine for COVID-19.

What is Dengue?

• About:
  • Dengue is a mosquito-borne tropical disease caused by the dengue virus (Genus Flavivirus), transmitted by several species of mosquito within the genus Aedes, principally Aedes aegypti.
    • This mosquito also transmits chikungunya and Zika infection.
• Serotypes of Dengue:
  • There are 4 distinct, but closely related, serotypes (separate groups within a species of microorganisms that all share a similar characteristic) of the virus that cause dengue (DEN-1, DEN-2, DEN-3 and DEN-4).
• Symptoms:
  • Sudden high fever, severe headaches, pain behind the eyes, severe bone, joint, and muscle pain, etc.
• Dengue Vaccine:
  • The dengue vaccine CYD-TDV or Dengvaxia was approved by the US Food & Drug Administration in 2019, the first dengue vaccine to get the regulatory nod in the US.
    • Dengvaxia is basically a live, attenuated dengue virus which has to be administered in people of ages 9 to 16 who have laboratory-confirmed previous dengue infection and who live in endemic areas.
• Challenges in Vaccine Development:
  • Developing an effective vaccine against dengue is tricky because it is caused by four closely related virus serotypes.
    • Each one interacts differently with antibodies in human blood. A person infected with DEN-1 is then protected against it for life, but not against the other three serotypes.
      • An ideal vaccine must target all serotypes.
  • Also, vaccines trigger production of antibodies that prevent the virus from binding to cells at later exposure. But with dengue, antibodies help the virus replicate and cause severe disease.