A More Transmissible and Possibly Lethal H5N1 Strain, huTX37-H5N1, Discovered in an Infected Farmworker in America!

Medical News: Researchers Uncover New Insights into the Spread and Impact of huTX37-H5N1
A novel, highly transmissible, and potentially deadly strain of the H5N1 avian influenza virus, dubbed huTX37-H5N1, has recently surfaced, originating from an infected farmworker in Texas. This variant, detected in a dairy farmworker who had contact with infected livestock, has shown alarming levels of transmission capability and lethality in laboratory tests on animals. Research findings indicate that the virus could represent a significant health risk to both humans and animals.


A More Transmissible and Possibly Lethal H5N1 Strain, huTX37-H5N1,
Discovered in an Infected Farmworker in America!

A collaborative team led by scientists from the University of Wisconsin-Madison, with support from Tokyo and Shizuoka Universities and the Research Center for Global Viral Diseases in Japan, published their findings in the journal Nature. Funded by the U.S. National Institute of Allergy and Infectious Diseases (NIAID), this investigation sheds light on the virus's capabilities, potential transmission routes, and vulnerability to antiviral drugs.
 
First Detection in an Infected Worker Sparks Study
The huTX37-H5N1 virus was first isolated from the eye of a dairy farm worker who experienced mild conjunctivitis after coming into contact with infected cows. Following its identification, researchers delved deeper into understanding this virus’s behavior, focusing on its transmissibility and effects on various animal models.
 
Their study revealed that the huTX37-H5N1 virus holds a mutation, PB2-E627K, commonly found in avian influenza strains adapted for mammals, enhancing its replication in mammalian hosts. This mutation was noted as a likely factor for its efficiency in animal models, raising concerns over its capacity to infect humans and potentially lead to severe health outcomes.
 
This Medical News report elaborates on these findings, providing key insights into the virus's transmission capabilities, effectiveness of antiviral treatments, and risks it poses.
 
Transmission and Severity of huTX37-H5N1 in Animal Models
In controlled laboratory experiments, huTX37-H5N1 showed lethality in mice and ferrets, common models for studying influenza. Tests revealed that even small doses of the virus could lead to significant infection and rapid disease progression. Mice required only 1 plaque-forming unit (PFU) of the virus for a lethal outcome, considerably lower than the 31.6 PFU needed for other bovine-derived H5N1 strains, emphasizing its potential severity.
 
In ferrets, which closely mimic human responses to influenza, the virus demonstrated even greater virulence. All ferrets infected with huTX37-H5N1 succumbed within five days, with virus concentrations peaking in their respiratory tracts. Previous studies of H5N1 strains had shown severe but less fatal outcomes in ferrets, underscoring that huTX37-H5N1 might have a more significant impact on mammalian hosts than its predecessors.
 
To test the virus’s transmissibility, scientists separated infected ferrets from healthy ones by a five-centimeter barrier, allowing only airborne transmission. The virus managed to infect nearby ferrets in 17% to 33% of exposure cases, indicating it can spread through respiratory droplets, though not with high efficiency. This limited airborne transmission hints at the potential risk for human spread, especially in close-contact settings like farms or densely populated environments.
 
Antiviral Effectiveness and Treatment Potential
A critical aspect of the study involved testing huTX37-H5N1's susceptibility to antiviral medications. Researchers evaluated common antiviral drugs to identify potential treatment options. The polymerase inhibitors favipiravir and baloxavir marboxil (marketed as Xofluza) showed efficacy in neutralizing the virus in vitro and in infected mice. Similarly, zanamivir, a neuraminidase inhibitor, effectively reduced viral replication. However, the virus exhibited lower sensitivity to oseltamivir, another neuraminidase inhibitor commonly marketed as Tamiflu, indicating limited effectiveness in treating huTX37-H5N1 cases.
 
These results underscore the importance of identifying effective treatment regimens, especially as this virus shows a high capacity for survival in mammalian respiratory tracts. While the study highlights several antiviral options, it also raises concerns about the need for alternative treatments should the virus develop further resistance.
 
Mechanism of Infection and Human Susceptibility
When studying the virus's ability to infect human tissue, scientists found huTX37-H5N1 capable of replicating within both lung and corneal cells. While the infected worker experienced only mild eye inflammation, the virus’s behavior in lab settings suggests it could cause more severe illness in humans. The PB2-E627K mutation, in particular, is associated with mammalian adaptation, enhancing the virus’s efficiency in human cells and potentially increasing the risk of systemic spread.
 
Despite the mild symptoms observed in the infected farmworker, the researchers suggest that higher doses or different exposure routes could yield more severe cases in humans. They propose that mild infections like conjunctivitis might be localized responses to low viral doses, while inhaled particles or contact with mucous membranes could lead to broader and more dangerous infections.
 
Containment and Public Health Implications
Given huTX37-H5N1’s transmissibility and potential for causing severe illness, researchers emphasize the need for heightened surveillance in dairy farms and similar agricultural settings. They advocate for strict containment protocols to limit the virus's spread within animal populations and prevent further human infections. The research team also points out that multiple exposures to seasonal flu strains might provide humans with partial immunity, although they stress that more research is essential to understand this factor.
 
These findings illustrate the critical role of monitoring and managing zoonotic diseases, which can evolve and spread rapidly through animal-human contact, especially in livestock-heavy regions. As viruses like huTX37-H5N1 demonstrate their potential to mutate and adapt to new hosts, public health measures need to keep pace with emerging threats to mitigate the risk of large-scale outbreaks.
 
Conclusion: Addressing Future Risks and Preparing for Containment
The emergence of huTX37-H5N1 serves as a reminder of the constant interplay between animal and human health. This study’s findings suggest that while the virus poses a considerable risk in controlled lab settings, it may not yet have the full capacity for efficient human-to-human transmission. However, its ability to infect multiple mammalian species, combined with the presence of high-risk mutations, calls for vigilance and proactive containment efforts.
 
The study underscores that the agricultural and medical communities must continue to monitor H5N1 strains in livestock, especially in densely farmed areas, to prevent further spillover events. The ability of huTX37-H5N1 to infect and replicate in human respiratory tissues raises concern for possible mutation or recombination events that could lead to easier human-to-human transmission.
 
Public health agencies worldwide are encouraged to review current biosecurity measures in high-risk areas and to explore antiviral stockpiling to prepare for potential outbreaks. As more is learned about huTX37-H5N1, these insights will help shape effective response strategies for protecting both animal and human populations.
 
The study findings were published in the peer-reviewed journal: Nature.
https://www.nature.com/articles/s41586-024-08254-7
 
For the latest H5N1 News, keep on logging to Thailand Medical News.
 
Read Also:
https://www.thailandmedical.news/news/passive-immunization-involving-avian-igy-anti-h5n1-antibodies-show-promise-against-influenza
 
https://www.thailandmedical.news/news/mirnas-could-help-combat-h5n1
 
https://www.thailandmedical.news/news/linc01615-enhancing-immunity-against-influenza