Chinese Scientists Warn of New H2N2 Influenza Strain That Could Be a Human Pandemic Threat
Nikhil Prasad Fact checked by:Thailand Medical News Team Nov 28, 2024 1 week, 6 days, 19 hours, 34 minutes ago
Medical News: Alarming Discovery of H2N2 Influenza Virus
A team of Chinese researchers has raised concerns about a newly identified strain of the H2N2 avian influenza virus. This virus, which has historically caused pandemics, shows alarming traits that could potentially lead to a human pandemic. The findings come from a collaboration between prominent institutions including Shanxi Agricultural University, the Chinese Academy of Sciences (CAS), and the China Agricultural University-China.
Chinese Scientists Warn of New H2N2 Influenza Strain That Could Be a Human Pandemic Threat
The research focused on the H2N2 avian influenza virus currently circulating in domestic poultry in China. This
Medical News report discusses the study's discoveries about its infectivity, transmissibility, and ability to adapt to mammals. Notably, one strain exhibited a dual receptor-binding ability, allowing it to bind both avian and human receptors - a feature critical for cross-species transmission.
H2N2: A Pandemic Strain With a History
H2N2 influenza is not new to public health experts. The 1957 "Asian Flu" pandemic, caused by an H2N2 strain, resulted in significant mortality before disappearing in 1968. However, H2N2 avian influenza viruses (AIVs) continue to circulate in birds, posing a latent threat of re-emergence in humans. As antibodies from the 1957 strain fade over time, the human population becomes increasingly vulnerable.
The study found that some H2N2 strains in poultry have evolved genetic and antigenic features distinct from the 1957 pandemic virus. Particularly concerning is the strain identified as Dk/FJ/2021, which demonstrates a dual receptor-binding property - capable of binding both avian and human receptors.
Key Findings on Infectivity and Adaptation
The researchers conducted extensive testing on the virus's infectivity and adaptation using animal models, including mice, guinea pigs, and ferrets. They observed that:
The Dk/FJ/2021 strain can infect and replicate in mice without prior adaptation, a critical step in the virus’s potential leap to humans.
After multiple passages in mice, the virus developed mutations that increased its virulence and replication efficiency in mammalian hosts.
Further analysis revealed that specific genetic mutations in the hemagglutinin (HA) protein - such as N144S - played a pivotal role in enabling the virus to bind human-type receptors. These mutations mirror the adaptations seen in past pandemic strains, such as the 1968 H3N2 virus, which initially had dual receptor-binding properties before evolving a preference for human receptors.
Enhanced Pathogenicity in Mammals
The Dk/FJ/2021 strain's pathogenicity was tested using a mouse-adapted (MA) model. Mice infected with the MA strain showed severe symptoms, including significant weight loss and fatality, compared to those infected with the wild-type virus. The MA strain also demonstrated enhanced replicatio
n in mammalian cells and human bronchial epithelial cells.
The study identified two key mutations in the adapted strain:
-PB2-E627K: A mutation that increases the virus's ability to replicate in mammalian cells.
-NS1-G183S: A mutation that suppresses host immune responses, facilitating unchecked viral replication.
Transmissibility: A Rising Threat
The transmissibility of the virus was tested in guinea pigs and ferrets, chosen for their similarities to the human respiratory system. The study found:
-The MA strain transmitted efficiently through direct contact and respiratory droplets in both animal models.
-Viral loads were significantly higher in animals infected with the MA strain compared to those exposed to the wild-type virus.
These findings underscore the potential for the H2N2 virus to spread among humans if introduced into the population.
Implications for Public Health
The study's results serve as a wake-up call for global health authorities. The ability of H2N2 to infect mammals, adapt to human-like conditions, and transmit efficiently highlights the urgent need for enhanced surveillance and preparedness. The researchers stress that understanding the genetic and antigenic characteristics of these viruses is critical for developing early warning systems and preventive measures.
Conclusion
This study provides critical insights into the genetic and molecular mechanisms that enable H2N2 avian influenza viruses to cross species barriers and adapt to mammals. With its dual receptor-binding capability and ability to acquire mutations that enhance replication and immune evasion, the Dk/FJ/2021 strain poses a tangible threat of sparking a new influenza pandemic. Strengthened surveillance and immediate action are imperative to mitigate this risk.
The study findings were published in the peer-reviewed journal: Nature Communications.
https://link.springer.com/article/10.1038/s41467-024-54374-z
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