Single H5N1 mutation enables easier human infection: study

A single modification in the protein found on the surface of the highly pathogenic avian influenza (HPAI) H5N1 influenza virus currently circulating in U.S. dairy cows could allow for easier transmission among humans, according to a new study published on Friday.

Current strains of the cow H5N1 virus are not known to be transmissible among people. However, infections have occurred in people exposed to infected wild birds, poultry, dairy cows and other mammals.

Influenza viruses attach to cells with a surface viral protein called hemagglutinin (HA). Scientists at Scripps Research, a well-known American medical research facility, used the H5N1 strain isolated from the first U.S. human infection with the cow strain 2.3.4.4b to test how mutations in the HA gene sequence affected the binding of that protein with avian versus human-type cell receptors.

They found single glutamine to leucine mutation at residue 226 of the virus HA was sufficient to enact the change from avian to human specificity.

The study, published on Friday in the journal Science, reinforces the need for continued, vigilant surveillance and monitoring of HPAI H5N1 for potential genetic changes that could make the virus more transmissible in humans, said the U.S. National Institutes of Health, which funded the study.