Media Advisory
Monday February 10, 2025
NIH study identifies previously unknown adaptation.
Colorized transmission electron micrograph of red and gold-stained influenza A virus particles isolated from a patient sample and then propagated in cell culture. Influenza A can infect humans and animals, including birds and pigs. Specifically, this image shows the H3N2 strain of influenza, isolated from a patient in Victoria, Australia, in 1975. Notable for forming both spherical andNIAID
What
Influenza A virus particles strategically adapt their shape, becoming either spheres or larger filaments, to enhance their ability to infect cells depending on environmental conditions, according to a new study by scientists at the National Institutes of Health (NIH). This previously unknown response may help explain how influenza A and other viruses persist in populations, evade immune responses, and acquire adaptive mutations, the researchers explain in a new study published in Nature Microbiology.
The study, led by intramural researchers at the NIH's National Institute of Allergy and Infectious Diseases (NIAID), was designed to determine why many influenza A virus particles exist as filaments. The filament shape requires more energy to form than a sphere, they say, and its abundance was previously unexplained. To find the answer, they developed a way to observe and measure the structure of the influenza A virus in real time as it forms.
The researchers discovered:
- Influenza A viruses rapidly adjust their shape when placed in conditions that reduce the effectiveness of infection, such as the presence of antiviral antibodies or host incompatibility.
- The shape of a virus is dynamic and affected by its environment, rather than being fixed by the strain, as is commonly believed.
- The study evaluated 16 different virus-cell combinations that resulted in predictable shape trends.
Previous experiments by the research team have shown that influenza A virus filaments can resist inactivation by antibodies, and the team is working to understand exactly how antibodies influence the shape and effectiveness of infection. They also plan to learn how viral mutations affect the shape of the virus. Many other viruses — such as measles, Ebola, Nipah, Hendra and respiratory syncytial virus — also incorporate a mixed-shape infection strategy, the researchers note.
Article
E Partlow, et al. Influenza A virus rapidly adapts particle shape to environmental pressures. Nature Microbiology DOI: 10.1038/s41564-025-01925-9 (2025).
Who
Tijana Ivanovic, Ph.D., is chief of the Single Virion Biology and Biophysics Unit in NIAID's Laboratory of Viral Diseases.
NIAID conducts and supports research—at NIH, in the United States, and around the world—to study the causes of infectious and immune-mediated diseases and to develop better ways to prevent, diagnose, and treat these diseases. News releases, fact sheets, and other NIAID-related materials are available at NIAID website.
About the National Institutes of Health (NIH): NIH, the nation's medical research agency, comprises 27 institutes and centers and is part of the U.S. Department of Health and Human Services. NIH is the primary federal agency that conducts and supports basic, clinical, and translational medical research, studying the causes, treatments, and cures for common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.
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