Context: Recently, scientists have identified a “newly emerged” strain of influenza virus that is infecting Chinese pigs and that has the potential of triggering a pandemic.
About G4 Swine Flu Virus 

• The new virus is a recombination of the 2009 H1N1 variant. The researchers have named the virus G4 EA H1N1. The virus is being considered a potential pandemic threat as it can grow and multiply in the cells that line the human airways.
• The researchers while conducting their study found that pig farm workers showed elevated levels of the virus in their blood.

Why new swine flu virus is a serious worry

• The G4 EA H1N1 flu virus is already circulating among swine. From 2011 to 2013 the most common variant of the EA H1N1 flu virus was the genotype 1 (G1) strain. But mutations in this strain eventually led to the emergence of a genotype 4 (G4) variant.
• The G4 EA H1N1 flu virus can bind to human-like SAα2,6Gal receptors.“SAα2,6Gal” is the name of a receptor found on cells that line your respiratory tract. Binding such receptors could help the virus attach itself to and eventually get into your cells.
• The virus can attach itself to human cells. It is not just any random human cell but cells that line with trachea. Trachea is the windpipe, the tube that connects upper respiratory tract with the lower part of our respiratory tract and lungs.
• Ferrets infected with the virus can spread the virus to other ferrets via respiratory droplets or direct contact.
• The virus is different from the virus strains that are already in flu vaccines. G4 EA H1N1 flu virus can infect and reproduce in cells lining your lower respiratory tract. Tests also showed that any immunity humans gain from exposure to seasonal flu does not provide protection from G4.

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.
• It was caused by a strain of the swine flu called the H1N1 virus, which was transmitted from human to human.
• Influenza viruses that commonly circulate in swine are called “swine influenza viruses” or “swine flu viruses”.
• Like human influenza viruses, there are different subtypes and strains of swine influenza viruses. Essentially, swine flu is a virus that pigs can get infected by.
• The symptoms of swine flu include fever, cough, sore throat, body aches, headaches, chills and fatigue.