Experts explain how the H5 flu adapts to infecting more animals

Since its discovery in 1996, the GS/GD line is highly pathogenic bird flu viruses with H5 haemaglutinin, including H5N1 and other H5NX subtypes, according to each continent and even Antarkctica.

In a recent review published in the journal Scientists from the Viroscience department, Erasmus MC, the Netherlands, reviewed the current knowledge of evolution, global spread and the growing risk of this persistent and flexible virus.

Influenza viruses

Flu viruses caused four human pandemies and countless explosions among the animal population in the last century. Among them, highly pathogenic influenza bird viruses (HPAIV) pose a serious threat because of their ability to evolve rapidly. While most bird influenza viruses are harmless among wild water birds, some mutated in more fatal forms, especially the H5 and H7 subtypes. When these viruses spill into poultry, they can evolve in highly pathogenic forms that cause a serious illness and death.

The GS/GD line of H5 viruses, which includes the well -known H5N1 subtype (for the first time identified in people in Hong Kong in 1997) and other H5NX variants, emerged from the complex mixture of bird viruses and has been diversified on many lines since then. This line has become a dominant global threat, spreading on continents and infecting a wide range of birds and mammals. In addition, despite constant supervision and control, the gaps remain in understanding how this virus spreads, evolves and adapts to new hosts, including people.

Current study

Scientists conducted a comprehensive review of scientific literature, reports in supervision and genetic analysis to understand the evolution and spread of highly pathogenic H5 influenza viruses from the GS/GD line. They tracked the beginnings of the virus for the explosion in 1996 in the national geese in Guangdong, China, and followed its genetic diversification through global explosions over the past 25 years.

The team examined how the virus changed in a process known as Reassortment, in which gene segments from different influenza viruses mix in the co -existing hosts, creating new variants of the virus. They focused on the explosions of wild birds, poultry and mammals, including tigers, sea lions, mink and dairy cattle.

The study also analyzed how the virus crosses species barriers. This included a review of molecular data on mutations in viral proteins, including hemaglutinin, neuraminidase and polymerase, which help the virus adapt to mammal cells. The structural features of hemaglutinin were studied, which affect the bond with the host receptors, as well as changes in the polymerase of viral ribonucleic acid (RNA), which increase replication in mammals. In addition, the study examined the immune response in various species and the way the virus avoids this defense.

To assess the impact on human health, the authors also reviewed data on confirmed people infections, risk of exposure and clinical symptoms, considering the role of environmental and agricultural practices in facilitating the spread of the virus, and examined current controls, such as housing, vaccination and supervision.

Key arrangements

The study showed that H5 viruses from the GS/GD line have undergone significant genetic evolution, enabling them to infect the wider range of species and persist all over the world. The virus, which originally circled in poultry, has now spread to wild birds and mammals, including rare relaxors on humans.

The most disturbing, recently reached milk cattle in the United States, where it spread primarily due to the movement of infected animals between farms. Contaminated adding equipment facilitates transmission on farms and causes widespread infections. The virus has now been detected on every continent, including in Antarctica, which means unprecedented expansion.

His ability to move again with other influenza viruses also generated many variants, including those with new gene combinations that increase adaptation to mammals. This genetic mixing has also improved the virus’s ability to bind to receptors similar to man and innate resistance of innate immune defense of mammals.

Since 1997, there are over 1000 cases of GS/GD linear infections in humans, with over 500 deaths; However, the real indicator of cases of case is uncertain due to the likely insufficient report of mild and subclinical infections and the variability of severity between foci. Most of the infections occurred after direct contact with infected poultry, but the last cases in the US with the participation of milk farm employees suggested new transmission routes. Although there was no permanent human transmission to human, the increase in mild or undetected human infections raises concerns about the pandemic potential.

The virus also had a destructive effect on wild nature, with high mortality among sea lions, seals and birds documented in America and Europe. Moving mammals to a mammal, especially in breeding colonies of mink and sea lion, also indicates that the virus can evolve towards a more efficient spread among mammals.

The review emphasizes that the available management options for wildlife epidemic management are limited and may include carcass removal and targeted vaccination of endangered species.

Conclusions

The ongoing spread and evolution of GS/GD H5 viruses, including H5N1 and other H5NX subtypes, emphasize the serious threat that these flu viruses create for animals, ecosystems and human health. With the increase in transmission evidence between species and the global distribution, this virus remains an upcoming problem.

The review emphasizes the critical need for a uniform “one health” approach, which integrates the health strategies of animal, people and the environment at the global level. The review showed that strengthening of supervision, vaccine strategy behavior, expanding the use of newer vaccine technologies, coordination of international vaccines and implementation wrestling as well as integration of efforts in the animal and people health sector are key steps to prevent future dining rooms and reducing the risk of potential pandemic.