G4 Flu Virus


  • In a new research, scientists from China– which has the largest population of pigs in the world – have identified a “recently emerged” strain of influenza virus that is infecting Chinese pigs and that has the potential of triggering a pandemic.

About the Virus

  • Named G4, the swine flu strain has genes similar to those in the virus that caused the 2009 flu pandemic.
  • The scientists identified the virus through surveillance of influenza viruses in pigs that they carried out from 2011 to 2018 in ten provinces of China.
  • They also found that the G4 strain has the capability of binding to human-type receptors (like, the SARS-CoV-2 virus binds to ACE2 receptors in humans), was able to copy itself in human airway epithelial cells, and it showed effective infectivity and aerosol transmission in ferrets.
  • The scientists report that the new strain (G4) has descended from the H1N1 strain that was responsible for the 2009 flu pandemic.
  • “Pigs are intermediate hosts for the generation of pandemic influenza virus.
  • Thus, systematic surveillance of influenza viruses in pigs is a key measure for pre-warning the emergence of the next pandemic influenza,” states the study.
  • It cannot be said if this new strain, if transmitted from pigs to humans, can transmit from one human to another.
  • The scientists suggest that controlling the prevailing G4 Eurasian-Avian like (EA) H1N1 viruses in pigs and closely monitoring human populations, especially workers in the swine industry, should be “urgently implemented”.

Back to Basics

2009 swine flu pandemic

  • The WHO declared the outbreak of type A H1N1 influenza virus a pandemic in 2009 when there were around 30,000 cases globally.
  • The US Centers for Disease Control and Prevention (CDC) defines swine flu as, “a respiratory disease of pigs caused by type A influenza viruses that regularly cause outbreaks of influenza in pigs. Influenza viruses that commonly circulate in swine are called “swine influenza viruses” or “swine flu viruses”.
  • Like human influenza viruses, there are different sub-types and strains of swine influenza viruses”.
  • Essentially, swine flu is a virus that pigs can get infected by. While humans typically do not get infected by such a virus that circulates among pigs, when they do, it is called “variant influenza virus”.
  • Human-to-human transmission among variant influenza viruses is limited.
  • As per the CDC, most commonly, humans may get infected by such viruses due to exposure from infected pigs.
  • The 2009 pandemic was caused by a strain of the swine flu called the H1N1 virus, which was transmitted from human to human.
  • The symptoms of swine flu include fever, cough, sore throat, body aches, headaches, chills and fatigue.

Source: Indian Express

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