WASHINGTON | researchers have discovered a strain of swine influenza virus in China, presenting all the characteristics capable of causing a future pandemic, according to a study published Monday in the us scientific journal PNAS.
The virus is called G4 and descend genetically from the H1N1 strain caused a pandemic in 2009: “they have all the essential features showing a high adaptability to infect humans,” the authors write, scientists from chinese universities and the Centre for the prevention and fight against disease chinese.
The work presented is large: from 2011 to 2018, 30 000 nasal samples have been carried out on pigs in the slaughterhouses of 10 chinese provinces and in a veterinary hospital, to isolate 179 swine influenza virus. The majority was of the new variety, which became dominant in pigs since 2016.
The researchers then carried out various experiments in the laboratory and on ferrets, the animals used in the research on the flu, because their symptoms are similar to those of humans: they have fever, cough, and sneeze.
They have observed that the virus G4 were more infectious, is répliquaient in human cells and induced in ferrets more severe symptoms than other strains.
In addition, according to tests in vitro, the immunity obtained after contact with the virus-human seasonal influenza does not protect against the G4.
The other bad news is that workers and people working with pigs were relatively likely to have been infected, or 10.4%, according to blood tests that have searched for the presence of antibodies to the virus. 4.4% of the general population was also contaminated.
The virus would already be past in humans, report scientists, but there is no evidence that it can be transmitted from human to human. Today is their fear.
“Pandemics occur when influenza viruses A with a new surface antigen HA becomes able to transmit from human to human,” conclude the researchers. “The concern is that infections of humans by the virus-G4 lead to human adaptation, and increase the risk of a human pandemic”.
It is necessary urgently, they say, to put in place a monitoring of the populations working in contact with pigs.
“The work is a salutary reminder that we run the constant risk of the emergence of zoonotic pathogens and livestock animals, with which humans are more in contact with wild animals, are the source of pandemic viruses important,” commented James Wood, head of the department of veterinary medicine at the University of Cambridge.