G4 Influenza Virus | UPSC

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G4 Influenza Virus UPSC IAS

G4 Influenza Virus | UPSC


New influenza virus isolated in pigs in China has pandemic potential

      WHY IN NEWS:

Human-to-human transmission possible, pre-existing immunity against flu of no help



For PRELIMS it is important to understand the new virus ! The recent discoveries are important for prelims . Well we feel this cannot be asked . It is too controversial just like Hantavirus .

For MAINS make sure you have enough key points on influenza and modes of transmission.


Scientists have identified a new ‘re-assorted’ influenza virus from pigs in China that has pandemic potential.



The virus has shown ‘increased human infectivity’ in swine industry workers.


  • The study has been published in Proceedings of National Academy of Sciences, a US journal.

This was based on extensive surveillance done among pig populations in 10 provinces of China from 2011-2018.


  • The serological exercise showed that the new gene of the H1N1 virus has efficient infectivity and transmissibility in ferret models.

“Reassortment” of viruses is a mechanism through which new strains of virus are generated that have new properties and can cause large scale epidemics; even pandemics.


  • MAJOR STRAIN : The swine influenza viruses have many lineages out of which Eurasian-avian (EA) is the most dominant one.
  • OUTBREAK :  The 2009 pandemic virus went back to pig herds after the outbreak.
  • NEW GENOTYPE : The new genotype (G4) of this EA strain of H1N1 virus produced due to reassortment was found to have acquired increased human infectivity.
  • INFECTIVITY : However, the current infectivity of all the new emergent EA re-assortants in human populations was not known.

  The researchers also clearly say that similar to the 2009 pandemic virus, G4 reassortant has all the essential hallmarks of a candidate pandemic virus.


  • DIRECT EFFECT : G4 virus could efficiently infect human airway epithelial cells found in the respiratory system.
  • CELLULAR DAMAGE : The researchers also assessed replicability in normal human bronchial epithelial cells and alveolar epithelial cells also found in the respiratory system.

Both are incidentally major targets of influenza virus infection.

  • REPLICABILITY : Replicability level of the G4 gene was similar to the 2009 pandemic virus at each point in time and produced virus progeny after 36-60 hours of seeding of infection.
  • ORGAN FAILURE : G4 virus caused much more damage to the lungs as compared to the 2009 pandemic virus.


  • The transmissibility potential of any virus is dependent on the fact as to how effective human-to-human transmission would be.
  • All the four variants of this gene showed effective transmission through direct contact.
  • Three of four variants of the G4 showed effective transmission through respiratory droplets too.
  • The researchers also confirmed aerosol transmission in G4.

  Aerosols are liquid particles having viruses and tend to sustain in the air for some time.

      IASbhai WINDUP: 

Incidentally, aerosol transmission has not been confirmed for the novel coronavirus SARS-CoV-2.

  • Whether pre-existing immunity against one form of a virus will work as a shield against new types depends on the fact as to how much the ‘drift’ or change is in the antigenic properties in the latter.
  • The researchers found that G4 type are antigenically distinct from the existing influenza strains.

Therefore, the existing seasonal influenza vaccines will provide no immunity against the new gene

  • So far, the researchers have found five human cases of EA strain in China, of which, two belonged to the G4 type.
     SOURCES:DownToEarth | G4 Influenza Virus | UPSC

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