Nasal swabs from more than 30,000 Chinese pigs over 7 years found an increase in an avian influenza virus (. / Stringer)

As the international community continues to redouble efforts to contain the spread of the coronavirus – the WHO assured that the pandemic is not « even close » to ending – Scientists in China identified another respiratory virus « with the potential to become a pandemic. »

Infectious disease researchers found that Chinese pigs are becoming more frequently infected with a strain of influenza that has the potential to jump into humans, according to an article published Monday by the Science portal.

A study published by the National Academy of Sciences explains that « when multiple strains of influenza viruses infect the same pig, they can easily switch genes, » in a process known as « rearrangement. » The specialists’ analysis focuses on a flu virus called G4.

The virus is a unique combination of three lineages: one similar to the strains found in European and Asian birds, the H1N1 that caused the 2009 pandemic, and a North American H1N1 that has genes from the avian, human, and swine flu viruses. « The G4 variant is especially worrisome because its core is an avian influenza virus, to which humans have no immunity, with mixed mammalian strain strains. »

« It appears that this is a swine influenza virus that is about to emerge in humans (…) Clearly this situation needs to be closely monitored »pointed Edward Holmes, a biologist at the University of Sydney who studies pathogens.

A team led by Liu Jinhua, from the Chinese Agricultural University (CAU), analyzed about 30,000 nasal swabs taken from pigs in slaughterhouses in 10 Chinese provinces, and another 1,000 swabs from pigs with respiratory symptoms. Those samples, collected between 2011 and 2018, threw 179 swine influenza viruses , the vast majority of which were G4 or one of the other five G strains of the Eurasian avian lineage.

« The G4 virus has shown a strong increase since 2016, and is the predominant genotype in circulation in pigs detected in at least 10 provinces », the team of researchers pointed out.

In line with what Holmes said, Sun Honglei, one of the authors of the article, stressed the importance of « strengthening surveillance » of Chinese pigs to detect the virus, since the inclusion of G4 genes from the H1N1 pandemic « may promote virus adaptation » leading to human-to-human transmission.

However, Martha Nelson, a biologist at the Fogarty International Center in the United States, assured that the probability of this triggering a new pandemic « is low. » He did acknowledge that we must be alert, since « influenza can surprise us. » In this regard, he recalled that no one knew anything about the pandemic H1N1 strain – which jumped from pigs to people – until the first human cases appeared in 2009. “There is a risk that we neglect influenza and other threats in this moment ”of COVID-19, he pointed out.

Influenza viruses frequently jump from pigs to humans. However, most are not transmitted between humans.

For his part, Nelson pointed out that it is difficult to determine if the spread of the G4 virus is a growing problem, since the size of the samples collected so far is relatively small, so he considered that more tests are needed in Chinese pigs.

In their study, Sun and colleagues found that G4s « have become adept at infecting and copying into human airway epithelial cells. » The researchers found antibodies against the strain in 4.4% of the 230 people tested, and that rate doubled in pig workers.

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