Deadlier Diseases

If you get an annual flu vaccine, you probably know that new strains of the virus emerge each year. All viruses, from influenza to Ebola, undergo genetic changes to adapt to their environments. Understanding the evolutionary patterns of viruses is critical for public health, allowing for preemptive measures against disease.

“You can start to create therapies that are necessary in the future by understanding more details of emerging virus pathogen problems,” said Yale Ecology and Evolutionary Biology professor Paul Turner, whose lab investigated how environmental changes such as deforestation or climate change affect viral patterns of evolution. The results, published in February in the journal Evolution, suggest that rates of environmental change greatly impact viral evolution.

The Turner lab studied Sindbis virus (SINV), a rapidly mutating RNA virus transmitted by mosquitoes, as a model for evolution dynamics. The scientists changed the type of host cells available to the virus, either suddenly or gradually, and used genomic sequencing to track viral changes over time.

For sudden environmental changes, highly beneficial mutations only occurred in the virus at the beginning of the experiment. In the gradually changing environment, however, beneficial mutations occurred throughout the experiment. This suggests that a slowly changing environment may allow viruses to optimize their machinery and become more dangerous. Such a pattern of evolution has far-reaching consequences—HIV is an RNA virus that adapts slowly to its changing human body environment, eventually targeting different target host cell-types within the human body.

The researchers hope that their work will ultimately help anticipate and prevent future disease outbreaks. “The kind of research we do gets at the predictive power of evolution,” said Turner.