Scientists Uncover Mystery of Flu Virus Evolution

Researchers at the University of Rochester Medical Center (URMC) have uncovered the mechanism that lets the flu virus evolve so efficiently within and between host species. In their research, the scientists found that the secret to the flu virus’s evolutionary success lies in its unique replication process. Previously, scientists thought that the flu virus evolved so quickly due to an error-prone replication process. However, this new research refutes that hypothesis. Instead, the researchers discovered that the flu virus’s unique replication process lets enough mutations form that the virus can easily spread and adapt to its host environment. In addition, this replication process allows just enough mutations to occur without causing catastrophic mutagenesis—that is, without killing itself in the process.

These new findings give us insights into how we may be able to control viral evolution,” Baek Kim, Ph.D., professor in the department of Microbiology and Immunology at UMRC and lead study author, said in a press release about the discovery. This research presents an attractive strategy for tackling the flu—making the influenza virus kill itself by amplifying the number of mutations made beyond the desired level, which is lethal for the virus.

In their study of the mechanisms behind flu virus evolution, the researchers used biochemical analysis methods to compare flu virus replication with human-immunodeficiency virus (HIV) replication. The scientists found that while the polymerases, that is, the enzymes, behind replication are quite error-prone in HIV, they are much more accurate in the flu virus. Though both viruses depend on mutations for survival, HIV is only able to replicate its genome a few times during an infection, meaning it isn’t able to produce that many mutations. In contrast, the flu virus replicates itself a number of times during an infection, and this gives it ample time to produce a huge number of mutations that allow the virus to thrive.

The results of the scientists’ research was published online in the April 29, 2010 edition of the open-access journal PLoS One. Researchers who contributed to this study included Shilpa Aggarwal, Birgit Bradel-Tretheway, Toru Takimoto, Stephen Dewhurst, and Baek Kim.

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