This giant virus hijacks cells’ protein-making machinery to multiply wildly

Scientists have confirmed a long-suspected ability of viruses: the capacity to commandeer the protein-making machinery of their host cells. This discovery, published in Cell on February 17th, provides experimental evidence that viruses can co-opt systems traditionally associated with living cells, dramatically altering the host’s function to produce more viruses.

Hijacking the Cellular Machinery

The research centers on a type of “giant virus” – so named for its unusually large genome – called Acanthamoeba polyphaga mimivirus. Researchers found that this virus utilizes a complex of three proteins to take control of the host’s ribosomes, the structures responsible for translating RNA into proteins. Instead of creating proteins needed by the host, the hijacked ribosomes begin churning out viral proteins.

Did You Know? Acanthamoeba polyphaga mimivirus is large enough to be visible under a standard light microscope.

A Powerful Toolbox

Frederik Schulz, a computational biologist at the Lawrence Berkeley National Laboratory in California, who was not involved in the study, noted that this virus possesses a “more powerful toolbox” than other viruses, enabling it to effectively replace the host’s normal cellular processes. Experiments demonstrated that viruses lacking any one of the three key proteins multiplied 1,000 to 100,000 times more slowly, highlighting their critical role in the infection process.

The Prevalence of Giant Viruses

While they may seem unusual, giant viruses are surprisingly common. They primarily infect single-celled organisms known as protists – including amoebae and protozoa – which are found “all over the place,” according to Eugene Koonin, an evolutionary biologist at the US National centre for Biotechnology Information in Bethesda, Maryland. The genome of Acanthamoeba polyphaga mimivirus is approximately five times larger than that of poxviruses, which have the largest genomes among viruses that infect humans.

Expert Insight: This research confirms a fundamental mechanism by which viruses can exert control over host cells, potentially reshaping our understanding of virus-host interactions and the evolution of these complex relationships.

What Could Happen Next

Further research could focus on identifying similar mechanisms in other giant viruses, and potentially even in smaller viruses. Scientists may also investigate how host cells attempt to defend against this type of viral hijacking. A deeper understanding of these processes is likely to reveal new targets for antiviral therapies. It’s also possible that studying these viruses will provide insights into the origins of complex life, as related research suggests.

Frequently Asked Questions

What is a giant virus?

Giant viruses are viruses with unusually large genomes, typically infecting single-celled organisms like amoebae and protozoa.

What did the researchers discover about Acanthamoeba polyphaga mimivirus?

Researchers discovered that this virus uses three specific proteins to hijack the host cell’s protein production system, forcing it to create viral proteins instead of its own.

How did the researchers confirm the role of these proteins?

By genetically engineering viruses to lack these proteins, researchers found that the modified viruses multiplied significantly more slowly – between 1,000 and 100,000 times slower – than those with all three proteins intact.

How might understanding viral protein hijacking influence future medical interventions?