Research into an emerging strain of swine flu has revealed that the G4 influenza virus has characteristics that could make it a candidate for a future pandemic. In a study published in the journal PNAS, experts describe the new swine flu virus, a genetic descendent of the H1N1 influenza strain that caused a pandemic in 2009.
Influenza has long been a cause for concern for infectious disease specialists. Since the H1N1 outbreak, researchers have been hot on the case of emerging strains of the illness which could be signs of an impending pandemic. Pigs are a common intermediate host for influenza so routine monitoring is carried out on captive populations to keep ahead of any new pathogens that could pose a potential threat to the wider population.
The study reviewed 30,000 nasal swabs taken from pigs from 2011-2018. The pigs were from a veterinary hospital as well as slaughterhouses across 10 Chinese provinces. Their analyses identified 179 swine flu viruses, the majority of which were a descendent of H1N1 termed G4, which first started to become dominant in swine populations in 2016.
According to the study authors, the G4 influenza possesses "all the essential hallmarks of a candidate pandemic virus.” Their conclusion followed investigations into how G4 behaved, including testing on ferrets, which are a common model for influenza as they experience similar symptoms to humans from the infection. They found that G4 was highly infectious, could replicate in human cells, and caused more severe symptoms in ferrets compared to other influenza viruses.
They also took blood samples from humans working with the pigs and found that 10.4 percent of them had antibodies for the virus. This shows the virus can pass to humans, however, it’s not yet been proven to be able to pass from person to person. If further investigations reveal that G4 is indeed a communicable disease between humans, it has the potential to spread to the wider population via those working in such industries.
In response to their findings, the study authors suggest that close monitoring in human populations for the G4 virus should be implemented as a matter of urgency. Their investigations revealed that exposure to seasonal flu doesn’t give humans immunity to the G4 virus, meaning prevention is key as the severity of illness suffered by those who caught it would depend on their ability to launch an effective immune response, something that has been problematic for patients infected with the novel coronavirus Covid-19.
However, before you go dashing out to stock up on toilet roll, it’s important to note that the study authors are not saying that a swine flu pandemic is imminent. Their research indicates that without proper control the G4 virus appears to have the traits of a pathogen that could successfully bring about a pandemic. Such monitoring studies are instrumental in preventing future outbreaks as they act as a prewarning for potentially catastrophic pathogens making it into the wider population.
“The work comes as a salutary reminder that we are constantly at risk of new emergence of zoonotic pathogens and that farmed animals, with which humans have greater contact than with wildlife, may act as the source for important pandemic viruses,” said Professor James Wood, Head of Department of Veterinary Medicine at the University of Cambridge, who wasn't involved in the study.