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Influenza virus evolution within a human host

last modified Feb 09, 2017 08:25 AM

Each year millions of people worldwide are infected with the influenza virus. New research conducted by Chris Illingworth in the Department of Genetics has shed light on an important process by which the virus evolves.

The genetic material of an influenza virus is contained on eight genetic segments. During an infection, if two different viruses infect the same cell, segments of the different viruses are shuffled in a process known as reassortment, coming together to form new viral strains. Reassortment events lay behind the emergence of the 2009 pandemic ‘swine flu’ virus.

The new research used genome sequencing to study how the influenza virus evolved over the course of infections that occurred in two sets of human volunteers. A mathematical model was used to estimate the extent to which reassortment created new genetic combinations during the course of each infection.

Analysis of the data suggested that the effect of reassortment is limited by the spatial separation of viruses within a single person. After starting an infection, influenza viruses multiply in different parts of the airway, and rapidly reassort with one another. However, limited movement of viruses between different locations in the airway has the consequence that most reassortment occurs between genetically similar viruses.

This work supports the conclusions of other studies, which have found different patterns of influenza virus genetic diversity in different parts of a single host. It forms part of a body of research carried out by the Illingworth group that aims to build a greater understanding of how viruses evolve during the course of single infections.

The full results of this research can be read here:

The study was conducted in collaboration with researchers both in the UK and internationally. Chris is funded by a Sir Henry Dale Fellowship granted by the Wellcome Trust and the Royal Society, and benefited from further funding provided by the National Science Foundation Research Coordination Network on Infectious Disease Evolution Across Scales, which supported a research visit to Duke University.

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