Acute viral infections, as seen with influenza and respiratory syncytial virus (RSV), cause disease quickly and disappear after only a brief infectious period. Yet in some cases, they can persist, for example leading to long-term respiratory problems in the case of RSV. This ability appears to be linked to the presence of defective viral genomes (DVGs), viruses with shorter viral genomes, missing some genes. These DVGs can arise when viruses replicate at high concentration in cells, and, paradoxically, are known to both trigger immune responses and promote long term infections. Researchers working on RSV found that cells infected with DVGs (pictured, in orange) survive better than those with full-length viral genomes (in green), because these DVGs activate a molecular pathway that protects the infected cells from being destroyed by the immune system. Understanding the role of DVGs in a range of viruses could suggest new ways to combat chronic infections.
Written by Emmanuelle Briolat
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