Test developed for the universal detection of all influenza A viruses, including in horses

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The influenza virus viewed under an electron microscope. Image: Centers for Disease Control and Prevention
The influenza virus viewed under an electron microscope. Image: Centers for Disease Control and Prevention

A test for the universal detection of all influenza A viruses, including those that infect the key hosts, birds, pigs, humans and horses, has been developed by researchers.

The new test, reported in the journal PLOS ONE, is said to offer an overall predicted detection rate of 99% on the analysed dataset.

The test, developed by Alexander Nagy and his colleagues, has the potential to be a useful tool under the global One Health Initiative, which recognises that human and animal health are inextricably linked.

A key component of the One Health concept is to ensure the ability to sensitively, specifically and universally detect influenza A viruses from different host species.

All influenza A viruses originate from the wild bird reservoir across a wide geographical range. They include many different genotype combinations of the eight genomic segments, but all are classically subdivided into subtypes defined by the hemagglutinin and neuraminidase glycoprotein combinations.

Influenza A viruses are characterized by extensive genetic variability. A mechanism of variability includes drift which affects all eight genetic segments, with additional genetic diversity and scope for viral evolution provided by reassortment among the segments.

The virus circulates among different hosts and can establish host-specific lineages. The four main hosts are avian, swine, human and equine, with occasional transmission to other mammalian species.

The host diversity is mirrored in the range of the lab-based tests for influenza A virus detection. Different tests are recommended by responsible health authorities for generic detection of influenza A virus in birds, swine or humans.

In order to unify monitoring in different hosts and apply the One Health approach, the study team from the Czech Republic, the Slovak Republic, England and Hungary developed a molecular-based test for universal detection of all influenza A viruses of all subtypes, species origin and global distribution.

They said their test design was centred on a highly conserved region of the virus’s matrix protein segment identified by a comprehensive analysis of 99,353 sequences. It showed high repeatability, reproducibility and robustness, they reported.

Their research resulted in important modifications of an earlier test design, reported in 2019, to compensate for the deficiency observed in the original version.

“(It) now meets the requirement for multi-species origin influenza A virus detection in accord with the One Health initiative.”

The authors noted that avian influenza viruses in particular are recognized as a key potential threat to poultry and human health globally, with the notifiable H5 and H7 AIV subtypes having the potential to mutate from low pathogenicity to the corresponding highly pathogenic strains.

Pigs are another important host which has been long known to serve as a “mixing vessel” for influenza A viruses of different species origins, enabling genetic reassortment to generate new circulating swine strains in pigs which may potentially transmit between species.

“Collaboration between human and animal health experts is prudent to respond to the threats posed by different influenza A virus strains, particularly where a newly-evolved strain may threaten to cross or has crossed the species barrier, and harmonise the appropriate prevention and control steps.”

The study team comprised Nagy, Lenka Černíková, Kateřina Kunteová, Zuzana Dirbáková, Saumya Thomas, Marek Slomka, Ádám Dán, Tünde Varga, Martina Máté, Helena Jiřincová and Ian Brown. They are variously affiliated with a range of institutions, including the State Veterinary Institute in Prague, in the Czech Republic; the National Institute of Public Health, National Reference Laboratory for Influenza, also in Prague; the SVFI-Veterinary Institute in Zvolen, the Slovak Republic; and the Animal and Plant Health Agency in Surrey, England.

Nagy A, Černíková L, Kunteová K, Dirbáková Z, Thomas SS, Slomka MJ, et al. (2021) A universal RT-qPCR assay for “One Health” detection of influenza A viruses. PLoS ONE 16(1): e0244669. https://doi.org/10.1371/journal.pone.0244669

The study, published under a Creative Commons License, can be read here

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