Characteristics of H5N1 influenza viruses in dairy cows may facilitate infection and transmission in mammals
July 8, 2024
The H5N1 virus present in dairy cows may facilitate transmission to mammals.
Media Advisory
Monday July 7, 2024
Ferrets are not susceptible to H5N1 viral infection through inhalation.
The particles are yellow/red and contain avian influenza A H5N1 viruses.CDC & NIAID
What is the best way to contact you?
In a series of tests, researchers found that the virus circulating among infected dairy cows in the United States was highly pathogenic (HPAI) H5N1 and caused serious illness in ferrets and mice when inoculated intranasally. The cow-infected H5N1 virus was found to bind to human and avian receptors. However, it did not spread well among ferrets when exposed through respiratory droplets. These results were published in NatureEvidence suggests that the H5N1 bovine HPAI virus (cows) may be different from other HPAI viruses. These viruses could also have characteristics that facilitate transmission and infection between mammals. However, at present it does not appear that they are capable of effective respiratory transmission from animals to humans.
An outbreak of HPAI H5N1 was first reported in March 2024 in dairy cattle in the United States. The virus spread to other flocks, causing deaths among cats, poultry and dairy workers. HPAI H5N1 virus isolates from affected cattle have a close relationship with the H5N1 virus that has been circulating among North American wild bird populations since 2021. These avian virus strains have evolved genetically over time and have spread across the continent, causing epidemics among wild mammals and birds. .
Researchers from Texas A&M Veterinary Medical Diagnostic Laboratory, Texas A&M University Shizuoka, University of Wisconsin-Madison, and Japan's University of Shizuoka conducted tests to better understand the characteristics of bovine HPAI viruses. They also tested the ability of mice and ferrets to reproduce and spread the virus. These animals are commonly used in studies of influenza A. The ferret is a useful model for studying the potential transmission of influenza in humans because they exhibit similar symptoms and immune responses.
Researchers administered increasing doses of HPAI H5N1 bovine influenza virus intranasally to mice (5 mice per group) and monitored their body weight and survival over a 15-day period. Mice that received higher doses of the virus died. Mice that received lower doses of the drug survived.
The researchers compared the effects of the bovine HPAI H5N1 virus to the Vietnamese H5N1 strain, which is similar to the human H5N1 influenza virus and the H1N1 influenza virus. Both viruses were administered intranasally. Mice infected with the Vietnamese H5N1 virus or the bovine HPAI virus had high levels of virus in their respiratory organs. This included muscle tissue and mammary glands. Only the respiratory tissues of the animals were infected with the H1N1 virus. Ferrets exposed intranasally to the bovine HPAI H5N1 virus exhibited elevated temperatures and loss of body weight. Scientists found high levels of the virus in the upper and lower respiratory systems and organs of ferrets, just as they did in mice. Ferrets, unlike mice, had no viruses in their blood or muscles.
The authors report that “Our pathogenicity tests in mice and rats revealed that HPAI H5N1 from lactating dairy cattle can induce severe disease following oral ingestion, or respiratory infection. Oral or respiratory infection can lead to systemic spread of the virus. in non-respiratory tissues, including mammary glands, teat or muscle.
The researchers infected four ferrets per group with H1N1 influenza or HPAI, both of which are known to spread effectively through respiratory droplets. Uninfected ferrets, housed next to infected animals a day later, were kept in the same cage. Ferrets infected with influenza virus showed signs of illness and had high levels of virus in nasal swabs taken over a period of several days. Only ferrets infected with H1N1 showed clinical signs, indicating that bovine influenza viruses do not spread effectively to ferrets through respiratory droplets.
Normally, human and avian influenza A viruses do not attach to the same receptors on cell surfaces to cause infection. Researchers have found that bovine HPAI H5N1 viruses can attach to both. This suggests that this virus could bind to cells in the upper respiratory tract in humans.
The authors stated that “collectively, our studies demonstrate that bovine HPAI H5N1 virus may differ from previously circulating HPAI H5N1 virus in possessing dual human/avian receptor binding specificity with limited transmission by respiratory droplets in ferrets.”
Researchers at the University of Wisconsin-Madison were funded by the National Institute of Allergy and Infectious Diseases.
The article below provides more information about the item.
In Eisfield The and all. The pathogenicity of the H5N1 bovine influenza virus and its transmissibility to mice and ferrets. Nature DOI: 10.1038/s41586-024-07766-6 (2024).
What are you waiting for?
Lauren Byrd Leotis Ph.D. is the chief of the Viral Respiratory Diseases Section in the NIAID Division of Microbiology and Infectious Diseases. She can be contacted to discuss the results.
You can contact us
For interview requests, contact the NIAID News and Science Writing Branch at (301) 402-1663. niaidnews@niaid.nih.gov.
NIAID supports and conducts research at NIH and throughout the United States and around the world to better understand the causes and develop new methods for diagnosing, preventing, and treating infectious and immune-mediated diseases. On the NIAID website, you can find press releases, fact sheets, and other NIAID materials. NIAID website.
The National Institutes of Health: NIH is the medical research agency of the United States Department of Health and Human Services. It includes 27 institutes and centers. NIH, the National Medical Research Agency, is the primary federal agency that conducts and supports basic, translational, and clinical medical research. It also studies the causes, treatment and cures of common and rare diseases. Visit NIH for more information about its programs and services. www.nih.gov.
NIH…Transforming discovery into health(r)
###
English 
French