Influenza A viruses adapt shape in response to environmental pressures

Monday, February 10, 2025

NIH study identifies previously unknown adaptation

Influenza A virus particles strategically adapt their shape—to become either spheres or larger filaments — to favor their ability to infect cells depending on environmental conditions, according to a new study from National Institutes of Health (NIH) scientists. This previously unrecognized response could 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 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 state, and its abundance has been previously unexplained. To find the answer, they developed a way to observe and measure real-time influenza A virus structure during formation.

*Colorized transmission electron micrograph of influenza A virus particles, colorized red and gold, isolated from a patient sample and then propagated in cell culture.*