G4 virus, transmitted by pigs, first appeared in 2013, not 2020

Reporter : He Liping

Publisher : The Paper, re-produced on ScienceNet

Ref : http://news.sciencenet.cn/htmlnews/2020/6/442162.shtm

Direct translation

Gao Fu and other scholars discovered a new type of recombinant swine influenza virus : It has the potential to spread in the population.

 

Image courtesy : Deccan Chronicle

Pigs are considered to be important hosts or "mixed containers" for pandemic influenza viruses. The systematic monitoring of swine flu viruses is essential for early warning and preparation for the next potential pandemic. A research team from China monitored nasal swabs of nearly 30,000 pigs from 2011 to 2018 and found that a recombinant influenza virus G4 EA H1N1 has occupied the main body of domestic swine influenza virus since 2016 and has Popularity potential. The research team recommends: quickly control the prevalence of G4 EA H1N1 virus in pigs, and closely monitor the breeding staff.

The above findings come from the latest paper Prevalent Eurasian avian-like H1N1 swine influenza virus with 2009 pandemic viral genes facilitating human infection of the international authoritative journal "PNAS" (PNAS) on 29 June 2020. The corresponding author of the paper is Professor Liu Jinhua of China Agricultural University School of Animal Medicine and Director of China Disease Control Gao Fu, and the first author is Sun Honglei, associate researcher of the Department of Preventive Veterinary Medicine of China Agricultural University School of Animal Medicine.

The monitoring lasted 8 years across 10 provinces and cities. Specifically, the researchers collected 29,918 swab nose swabs from pig farms in Anhui, Beijing, Hebei, Heilongjiang, Henan, Jiangsu, Jilin, Liaoning, Shandong and Tianjin, and 1016 swine nose swabs with respiratory symptoms Sampling of lungs or lungs. The researchers identified a recently emerged genotype 4 (G4) recombinant Eurasian avian influenza (EA) H1N1 virus (hereinafter referred to as G4 EA H1N1, referred to as G4 virus), which has the 2009 H1N1 pandemic and triple recombination (TR) derived internal genes have dominated the pig herd since 2016. The so-called recombination means that when multiple influenza viruses infect the same pig, they can easily exchange genes. This process is "recombination".

Similar to the 2009 swine flu virus, the G4 virus can bind to human-type receptors, can produce more progeny viruses in human airway epithelial cells, and shows efficient infectivity and aerosol transmission ability in ferrets. Ferrets are a popular animal model for studying human influenza.

In addition, the low-antigen cross-reactivity of the human influenza vaccine strain of EA H1N1 virus recombinant with G4 indicates that the existing population immunization cannot provide protection against the G4 virus. Further serological monitoring of the occupationally exposed population showed that 10.4% (35/338) of the pig workers were positive for the G4 EA H1N1 virus, especially for participants aged 18 to 35, whose seropositivity rate was 20.5% (9/44 ), which shows that human infectivity is mainly enhanced by G4 EA H1N1 virus. This infectivity greatly increases the chances of the virus adapting in humans and raises concerns about the possibility of pandemic viruses.

According to evolutionary tree analysis, the EA H1N1 virus has six genotypes, G1-G6. G1 is the original EA H1N1, and other genotypes, including G4, were generated by the replacement or mutation of certain genes from 2011 to 2018.

The analysis results of swine nose swabs showed that the G4 virus had appeared in 2013, became mainstream in 2016, and accounted for an absolute majority in 2018.

"Science" website quoted Edward Holmes, an evolutionary biologist at the University of Sydney who studied pathogens, said: "From the current data, this seems to be a swine flu virus that will appear in humans." But the study also has its own The limitation is that the sample is not big enough. China has 500 million pigs. This study only gave people a little understanding of swine flu strains.

The paper reports that in a household survey, researchers found that 4.4% of the 230 respondents had antibodies to G4, and this ratio more than doubled among pig workers. In addition to strengthening surveillance, Sun Honglei said that it makes sense to develop a G4 vaccine against pigs and humans.