Research Shows Single Modification on H5N1 Protein Could Allow for Easier Transmission Among Humans

New research funded by the National Institutes of Health (NIH) has found that “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.”

Current strains of H5N1 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). The HA latches on to sugar (glycan) molecule receptors on cells to cause infection. Avian (bird) influenza viruses—like H5N1—have not infected people often because the human upper respiratory tract lacks the avian-type cell receptors found in birds. Scientists are concerned that viruses could evolve to recognize human-type cell receptors in the upper airways and acquire the ability to infect people and spread between them.”

Scientists used the strain of the virus isolated from the first U.S. human infection in their research. They “introduced several mutations into the viral HA protein that had been observed to occur naturally in the past and found that one mutation, called Q226L, improved the ability of the protein to attach to receptors typically found on human cells, especially when an additional mutation was present. Importantly, the researchers introduced the genetic mutations only into the HA surface protein and did not create or conduct experiments with a whole, infectious virus.”

The findings stress the importance of “continued efforts at outbreak control and continued genomic surveillance to monitor for the emergence of HPAI H5N1 genetic changes and maintain public health preparedness.”