The discovery of a new influenza virus that could cause a pandemic in pigs has sparked immediate concern in the pig industry and beyond, according to a paper published in the prestigious SCI journal.
“It’s not quite person-to-person yet.”
China Agricultural University college of Veterinary Medicine Professor Liu Jinhua in an exclusive interview with the first Business reporter said.
Liu is the lead author of the paper.
Fan Fuhao, a researcher at the Ministry of Agriculture and Rural Affairs’ Breeding Pig Quality Supervision, Inspection and Testing Center in Guangzhou, also told China Business News, “The article serves as a reminder and a warning, not a human case of swine flu. I hope it will not be hyped up.”
The virus is limited to infection
Jin-hua liu team on June 29, China agricultural university and the Chinese center for disease control and prevention Gao Fu team published in the proceedings of the national academy of sciences (PNAS), according to a study since 2016, a named G4 (genotype 4) recombinant strains of influenza virus, began to increase in pigs in China and gradually dominated, at least from 10 provinces to detect the virus in pigs.
In fact, other research teams have isolated the virus in pigs since 2013.
Between 2011 and 2018, researchers collected more than 30,000 nose swabs from pigs from slaughterhouses and veterinary hospitals in 10 provinces in China to monitor influenza viruses and found multiple gene rearrangements of influenza viruses, according to the paper.
G4 is a religand of three viruses: the Eurasian avian influenza virus, the PDM /09 virus that caused the 2009 pandemic, and the North American triple virus.
At the end of December 2015, research results also published in the journal PNAS showed that the Eurasian AVIAN H1N1 virus has the potential to spread among humans and is the most likely virus to cause the next human influenza pandemic, which should be given high attention.
The work was done by a team led by Chen Hualan, a researcher at the Harbin Institute of Veterinary Medicine of the Chinese Academy of Agricultural Sciences.
The paper also notes that the widespread spread of The G4 virus in pigs inevitably increases its exposure to humans.
So far, published studies have shown that There have been two cases of G4 infection in China, reported in 2016 and 2019.
Genetic analysis showed that the two cases were caused by a virus similar to The G4 Eurasian Avian H1N1 virus.
And, “Similar to PDM /09, G4 binds to human cell receptors, replicates in human respiratory epithelial cells, and causes disease and transmission in ferrets.
Moreover, the cross-reactivity of human influenza vaccine strains against G4 virus is low, i.e. the existing human influenza herd immunity is insufficient to effectively resist the virus “.
The content has drawn intense attention.
Serological monitoring of pig farm workers revealed a seropositivity rate of 10.4% (35/338), especially among workers aged 18 to 35, of 20.5% (9/44).
In addition, there was a 4.4% seropositive rate in the general population.
For such a high positive rate, Liu explained that this is only a serum monitoring data, not virus data, not isolated from the pig farm workers G4 virus.
Because people infected with seasonal influenza viruses or vaccinated against influenza can have some effect of antibody cross-reactions, the actual number of infections should be lower than the number of serum monitors.
At the same time, he stressed, it was not yet human-to-human transmission.
During the investigation, it was found that no obvious influenza-like illness occurred in the pig farm workers with positive antibody, and no cluster disease occurred in the pig farm workers.
Liu Jinhua thinks, look now, this virus has limited infective ability only, after the person is contacted, may appear antibody turns positive, but the virus still is difficult to replicate in the person body effectively cause to come on.
Surveillance is not in vogue
Zoonoses, which are transmitted from animals to humans, are among the hottest topics in academic circles due to coVID-19, said an industry expert who studies zoonoses.
The value of the paper is that combining The G4 virus with reported human cases is a wake-up call.
However, whether there is human-to-human transmission of the G4 virus after transmission to humans will need to be closely watched in the future.
Feng Yonghui, chief analyst of Sohu.com, told China Business News that swine flu is not among the top three swine diseases in terms of morbidity, mortality and transmission.
As for G4, the new swine flu virus, it is necessary to pay attention to it, but more importantly, scientific and objective interpretation of the experimental data in the paper is needed, otherwise it will easily cause unnecessary panic.
‘You can’t just use lab studies as an analogy,’ Mr. Feng said. ‘After all, the sample size is limited.’
“If the study shows that 10.4 per cent of pig farm workers have been infected, then out of China’s 40 million pig farmers, more than 4 million people will be infected”, such an inference is clearly unscientific.
In terms of the pathogenicity of the virus to pigs, laboratory data showed that the pathogenicity of G4 virus was higher than that of the “pure” Eurasian avian virus in the early epidemic, and pig farms should pay attention to the prevention and control of the disease, Liu said.
I would also like to remind you that after the African Swine fever epidemic in 2018, the structure of China’s pig breeding industry has undergone fundamental changes. Large-scale pig farms have attached great importance to biosafety, effectively prevented the occurrence of a variety of infectious pig diseases, and largely suppressed the prevalence of G4 virus in pig herds.
From the perspective of public health safety, although few cases of infection have been reported, there are still cases of human infection. The threat is real and it is important to be vigilant.