BREAKING! Canadian Scientists Warn About Existing Highly Lethal H5N1 Avian Influenza Reassortant Strains Circulating In North America
: The world is facing a new threat: the highly lethal H5N1 avian influenza virus is wreaking havoc in the animal kingdom. Since 2014, the genetically distinct clade 18.104.22.168 has been circulating in Eurasia, Africa, and briefly in North America, killing millions of wild and domestic birds. In December 2021, the clade 22.214.171.124b H5N1 virus was first isolated from poultry and wild birds in Canada. The virus has since spread, infecting numerous terrestrial and aquatic mammalian species. The potential for spillover into the human population is a critical concern.
Canadian scientists have now discovered that multiple naturally circulating reassortant H5N1 viruses can replicate in primary human airway epithelial cells and cause lethal disease in various mammalian species. One isolate, A/Red Tailed Hawk/ON/FAV-0473-4/2022, efficiently transmitted between ferrets through direct contact, resulting in lethal outcomes. This alarming discovery is unprecedented, as H5 subtype viruses have not historically transmitted effectively between mammals.
The highly airborne A/Red Tailed Hawk/ON/FAV-0473-4/2022 H5N1 isolate was so virulent and exhibited enhanced neurotropism, high viral replication rates and induced rapid hyperinflammation in inoculated ferrets and mice with rapid deaths!
The current 126.96.36.199b clade H5N1 virus is a descendant of the A/goose/Guangdong/1/1996 virus, which was first identified in Southeast Asia in 1996. Since then, the virus has evolved and spread significantly, with clade 2 viruses, specifically H5 HA lineage 188.8.131.52, including H5N2, H5N6, and H5N8, dominating globally since 2014.
The H5N8 virus caused the majority of infections from 2014 to 2020, including outbreaks in North America.
In 2020, clade 184.108.40.206b viruses spread to Asia, Africa, and Europe via migratory birds. By autumn 2021, H5N1 viruses were detected in North America, in both wild and domestic birds. In spring 2022, scientists observed reassortment of the 220.127.116.11b virus with North American lineage IAVs in samples collected from domestic and wild birds, as well as terrestrial and marine mammals.
The spread of HPAI H5N1 viruses to North America has led to the culling of millions of domestic birds and an unprecedented die-off of wild bird populations.
The ability of novel reassortant H5N1 viruses to cause large-scale epizootics in mammalian species and potentially infect humans is not well understood.
The Canadian researchers led by scientist from the Public Health Agency of Canada isolated five distinct HPAI H5N1 viruses from infected wild animals in Canada, three from avian species and two from red foxes.
Genetic characterization revealed unique combinations of North American and Eurasian avian virus genes, as well as lysine (K) or valine (V) residues at position 627 of PB2, a known adaptation for virulence in mammals.
Four viruses tested in BALB/c mice, deer mice, and ferrets as models of mammalian infection exhibited differential virulence.
In addition to lethal disease following direct inoculation, infection of ferrets resulted in efficient contact (horizontal) transmission leading to lethal disease with one virus isolate,
with additional evidence of airborne transmission.
These results highlight the possibility of HPAI H5N1 viruses acquiring adaptations through sustained transmission chains in mammalian populations, increasing the potential for long-term mammalian adaptation.
The global spread of H5N1 viruses since 2020 has resulted in an unprecedented number of outbreaks in wild and domestic bird populations and the deaths of millions of animals including many different types of mammals as covered in various H5N1 News
coverages over the last few months. The new H5N1 Reassortant strains are literally just a ‘step’ or even ‘half a step’ away from causing a catastrophic pandemic among the global human population.
The study highlights the ongoing threat posed by the highly pathogenic H5N1 clade 18.104.22.168b avian influenza virus to not only avian species but also to a variety of mammalian hosts, including humans. The findings underscore the potential for these viruses to acquire genetic adaptations that may facilitate increased virulence, replication efficiency, and transmissibility in mammals.
As we face the possibility of future outbreaks and pandemics, it is of utmost importance to prioritize ongoing surveillance of circulating HPAI A(H5N1) viruses across species, including humans. This will enable us to promptly identify viruses with pandemic or outbreak potential in mammals and implement appropriate prevention and control measures.
Additionally, further research is needed to fully characterize the genetic determinants responsible for the observed mammalian adaptation and pathogenicity of these viruses. This information will be invaluable for developing targeted surveillance strategies, as well as informing the development of effective H5-specific vaccines and antiviral therapies.
The current global landscape is characterized by the ever-increasing interconnectivity of ecosystems, human populations, and animal species. In this context, understanding the potential risks associated with the emergence and spread of novel viruses, such as the H5N1 clade 22.214.171.124b avian influenza virus, is more important than ever. Through the continuous advancement of our knowledge and surveillance capabilities, we can better protect both human and animal health in the face of these evolving threats.
Contrary to what some scientists are claiming that the H5N1 Avian flu virus needs at least 3 to 4 more mutations to effectively transmit among humans. It seems that that it might only need one easy mutation based on the data for these newly emerged reassortant H5N1 strains detected in Canada.
The study findings were published on a preprint server and are currently being peer reviewed.
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