Viruses a major source of human evolution

The flu virus is constantly evolving resistance to vaccines.

In disease ecology, we learn that the interaction between hosts and parasites can shape communities and drive evolution. In the so called coevolutionary arms race, the parasite or pathogen optimizes its ability to infect hosts while hosts face selective pressure to adapt defenses. An example of this can be seen in the flu virus, where a single mutation can render a vaccine useless. While a virus is in a host, it can come into contact with thousands of different proteins in its attempt to spread and reproduce. Proteins are necessary for cell functioning, and their ability to change allows for greater immune response to threats. Along this reasoning, it is conceivable that viruses would be dominant drivers in cell evolution, as compared to pressure from predators or environmental conditions.

A new study published by Dr. David Enard of Stanford University has attempted to measure just how great an affect viruses have on the evolution of humans and mammals. While previous research has examined adaptations in individual proteins comprising the immune response, Dr. Enard preformed a comprehensive study of all proteins that interact with viruses. Thirteen-hundred proteins of interest where chosen from the genomes of 24 mammals, and analyzed through a ‘big-data’ algorithm to compare the evolutionary changes of proteins that come into contact with viruses to those that don’t.

The study found that 30% of protein adaptations could be attributed to virus selection pressure. This shows how any protein that interacts with a virus, not just specialized immune proteins, could have an induced adaptation. However, compared to other proteins in the body, those that interacted with viruses were evolving three times as much.

The study is notable as previous research had yet to clearly document a strong correlation between evolutionary adaptations and viruses. The information could be used to gather a better appreciation of how organisms evolve and explain why related species evolved different parts for identical cell function. Furthermore, understanding which proteins of the cell were important in fighting viruses in the past could be used to develop new treatments for the future.

David Enard et al, Viruses are a dominant driver of protein adaptation in mammals, eLife (2016)



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