H1N1-evolving to escape elimination

A study, led by Associate Professor Gavin Smith and Assistant Professor Yvonne Su from Duke-NUS, has shown that the later stages of H1N1 virus evolution are driven by our immune system. This is the first study to track a new virus and its transitions as it established itself in humans. The findings may help to develop novel therapeutic approaches for fighting the virus and future pandemics.

H1N1-evolving to escape elimination
A diagram depicting the global spread of H1N1

Swine flu, or the H1N1 virus, spread rapidly among humans in 2009 and caused the first influenza pandemic in over 40 years. As the virus had previously only circulated in swine, humans had no immunological protection against it. This contributed to a global pandemic resulting in over 150,000 deaths within its first year. While previous studies have documented the initial ‘host switching’ event – the virus jumping from swine to humans – little is known about the evolution of the virus after that.

Dr Smith and Dr Su’s team from the Duke-NUS Programme in Emerging Infectious Diseases analysed over 3,000 H1N1 viral genomes globally, including 214 new genomes from Singapore, in their study. Their work showed that initially, the viruses underwent broader mutations that aided their adaptation from swine to humans. Eventually the viruses evolved into more advantageous variants that prevented them from being recognised by our immune system. Understanding the location and transition in the different types of mutations are important for developing more effective vaccinations and potential drugs to slow down future pandemics.

“Virus evolution helps explain why only two out of 10 samples infected by the 2014 version of the virus had a reaction to the vaccine formulated in 2009,” said Dr Smith. “Our findings have also identified multiple ancestral populations and numerous geographical regions that could act as a starting ground for local epidemics in the future.” Further studies to investigate the changing genomics and interactions of the H1N1 virus are required to gain better insight into the long-term evolution dynamics of the virus.

This study was published in Nature Communications, and is supported by the Singapore Ministry of Health’s National Medical Research Council under its Investigator Research Grant, the Singapore Ministry of Health’s (MOH) MOH Communicable Diseases Public Health Research Grant, the Duke-NUS Signature Research Programme, with funding from the Agency for Science, Technology and Research and the Singapore MOH, and contracts from the US National Institutes of Health.