A Journal of Virology paper from Emily Bruce’s University of Vermont lab found H1N1 and H3N2 do not enter human lung cells the same way, overturning the view that seasonal flu strains use a common route.
Rab11B emerged as the key difference: when the protein was reduced in human cells, H3N2 could neither enter nor replicate, while H1N1 remained able to infect cells.
The result challenges the long-held idea that sialic acid alone serves as influenza’s universal binding point, suggesting H3N2 also depends on host proteins being positioned correctly for entry.
Researchers and outside virologists said the finding could sharpen antiviral development by pointing to more specific targets than sialic acid, which is widespread across human cells.
The work lands as flu remains a major Vermont health concern; the state recorded 83 influenza outbreaks last winter in places including schools and long-term care facilities.
Could targeting a human protein instead of the flu virus itself be the key to ending severe seasonal outbreaks?
Why did two common flu strains evolve different ways to infect our lungs, and what does it mean for future pandemics?
This flu discovery was an accident. What other viral weaknesses are we missing that could prevent the next pandemic?
Paradigm Shift in Flu Biology: H3N2’s Unique Dependence on Rab11B Opens Door to Strain-Specific Treatments
Overview
A groundbreaking study from Dr. Emily Bruce’s lab at the University of Vermont, published in June 2026, has changed how scientists understand H3N2 influenza infection. The research revealed that, unlike the long-held belief that all flu viruses use sialic acid to enter human cells, H3N2 specifically depends on the host protein Rab11B for successful infection and replication. This dependency is not shared by the H1N1 strain, highlighting a key difference between these common flu viruses. This discovery opens new possibilities for targeted treatments and marks a major shift in flu biology.