Scientists in China identified another respiratory virus “with the potential to become a pandemic”The analysis of the specialists focuses on a virus detected in pigs, called G4.
As the international community continues to redouble efforts to stem the spread of the coronavirus – the WHO said the pandemic is “not even close” to ending – scientists in China identified another respiratory virus “with the potential to become a pandemic.”
How Was G4 Virus Discovered?
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 journal PNAS (Procedures of the National Academy of Sciences of the United States) explains that “when multiple strains of influenza viruses infect the same pig, they can easily exchange genes”, in a process known as “rearrangement” . The specialists’ analysis focuses on a flu virus called G4.
What Is G4 Virus?
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 this is a swine influenza virus that is about to emerge in humans … Clearly this situation needs to be closely monitored,” said Edward Holmes , a biologist at the University of Sydney who studies pathogens.
A team led by Liu Jinhua of 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, yielded 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 “can 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.” She did acknowledge that we must be alert, since “influenza can surprise us.” In this regard, he recalled that nobody 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. For this reason, Sun opined that a G4 vaccine should be developed for both pigs and humans.
China, which has the largest population of pigs with more than 500 million, rarely uses influenza vaccines in pigs. Nelson said that on US farms it is common, but vaccines tend to have little effect because it is often outdated and does not match circulating strains