Host-virus relationships: a sum of many battles.

The spread of pathogenic viruses implies host infection, replication, and virus dissemination. In each step, viruses have to overcome the host defenses designed to neutralize the threat they pose. The host-virus relationship represents a constant multistage battle for power as the host/cell does not voluntarily give in to the viral enemy. Upon infection, cells recognize viral pathogen-associated molecular patterns, activating the innate antiviral defenses. As such, during most of the replication cycle, the virus has to deal with the cellular antiviral response. At this point, it should not be forgotten that viruses are obligate intracellular parasites and thus are entirely dependent on the host cell for their replication. This dependency has pushed viruses to evolve unorthodox strategies to subvert and repurpose cellular factors and processes required for efficient replication. Even if a virus has the potential to be successful at each step necessary for its spread, this does not mean it has won the war against the host. Another threat to viruses is represented by antiviral drugs designed to diminish their survival and promote the host's wellbeing. This editorial outlines the contents of this special 'In the Limelight' issue of FEBS Open Bio focused on Virology. The section contains four review articles, each focused on a particular aspect of virus-host interaction, including the antiviral response, subversion of the host translational machinery, repurposing of cellular factors, and the development of antiviral drugs.