Giant virus hijacks cells’ protein-making machinery to multiply wildly

Scientists have identified a giant virus that can hijack a host cell’s protein-making machinery to churn out copies of itself — the first experimental evidence that viruses can co-opt this particular system, which is typically associated with cellular life. To take control, the virus attaches a three-protein complex to the host’s ribosomes — part of the apparatus cells use to make proteins — which gives viral RNA preferential access. Researchers suggest that the virus makes this protein complex using genes that it ‘stole’ from hosts early in its evolutionary history.

AI scans RNA ‘dark matter’ and uncovers 70,000 new viruses

A trawl of genomic samples archived in publicly available databases has revealed 70,500 RNA viruses that were previously unknown to science, many of them weird and nothing like known species. Researchers developed a deep-learning model to recognize the gene sequences that encode a key protein in the ubiquitous microorganisms. Looking at more than 10,000 samples from around the world, the team found new viruses in environments that included air, hot springs and hydrothermal vents.

AlphaFold reveals how viruses evolved

Protein structures predicted by AI models have revealed some twists in the evolution of flaviviruses — a group that includes hepatitis C, dengue and Zika viruses. Researchers used DeepMind’s AlphaFold2 and Meta’s ESMFold to generate more than 33,000 predicted structures for proteins from 458 flavivirus species. They already uncovered some surprises. For example, the hepatitis C virus infects cells using an entry system similar to one seen in the pestiviruses — a group that includes animal pathogens like swine fever. Another big surprise was the discovery that some flaviviruses have an enzyme that seems to have been stolen from bacteria.

Bizarre bacteria scramble workflow of life

Bacteria have stunned biologists by reversing the usual flow of information. Typically genes written in DNA serve as the template for making RNA molecules, which are then translated into proteins. Some viruses are known to have an enzyme that reverses this flow by scribing RNA into DNA. Now scientists have found bacteria with a similar enzyme that can even make completely new genes — by reading RNA as a template. These genes create protective proteins when a bacterium is infected by a virus.

Giant viruses raise questions about life

The discovery of two giant new viruses has made scientists ponder the origins of life.  The so-called Pandoraviruses are at least twice the size, both in terms of their physical scale and genome complexity, of the previous record holder Mimivirus.