Recent research funded by the National Institutes of Health (NIH) and published in Science has found that a single modification in the surface protein of the H5N1 avian influenza virus currently circulating in U.S. dairy cows could make it more easily transmissible among humans. This study highlights the need for ongoing surveillance and monitoring of the HPAI H5N1 virus for potential genetic changes that could increase its ability to spread between people. While the current strains of the virus are not known to be human-transmissible, infections have occurred in people who have been exposed to infected wild birds, poultry, dairy cows, and other mammals.
Influenza viruses infect host cells by using a surface protein called hemagglutinin (HA), which binds to sugar molecules on the surface of cells. The H5N1 avian influenza virus, typically found in birds, has not been able to infect humans easily because human cells lack the specific receptors that the virus normally targets. However, there is concern that the virus could evolve to recognize human-type receptors in the upper respiratory tract, potentially enabling it to infect humans and spread from person to person.
To investigate this possibility, scientists at Scripps Research tested how mutations in the HA gene of the H5N1 strain isolated from a human infection in the U.S. affected the virus’s ability to bind to avian versus human receptors. They found that one specific mutation, Q226L, improved the virus’s ability to attach to human-type cell receptors, particularly when accompanied by another mutation. This result suggests that the virus could adapt to more easily infect humans under the right conditions.
Despite this finding, the study emphasizes that the presence of the Q226L mutation alone does not mean that HPAI H5N1 is on the brink of causing a human pandemic. Other genetic changes would likely be necessary for the virus to fully acquire the ability to transmit between humans. Nevertheless, the increasing number of human cases resulting from direct contact with infected animals underscores the importance of controlling outbreaks and continuing efforts to monitor genetic changes in the virus.
The research, funded by the NIH’s National Institute of Allergy and Infectious Diseases (NIAID), emphasizes the critical role of genomic surveillance in pandemic preparedness. The study’s findings underscore the necessity of vigilant monitoring of the H5N1 virus to detect any genetic changes that could make it more transmissible to humans, thus ensuring that public health efforts remain ahead of potential threats.
