Strategies to escape viral infection in archaea
Archaeal viruses are some of the most mysterious and diverse viruses on Earth. To date, little is known about how these viruses recognize, infect, and interact with their hosts. This thesis explores virus-host relationships using haloarchaea, a group of salt-loving archaea, to better understand how archaeal viruses infect cells and what determines which hosts they can attack.
A large-scale infection screening of 100 haloarchaeal viruses revealed that Haloferax gibbonsii LR2-5 is susceptible to many viruses, making it a valuable model organism for future studies. Detailed experiments with one virus, HSTV-2, showed that infection can proceed very differently depending on the host, from slow and destructive to fast but non-lethal.
The thesis also introduces a new genome sequencing approach using Oxford Nanopore technology to explore how archaea defend themselves against viruses. Analysis of newly sequenced genomes revealed that hosts with more antiviral defense systems tend to be more resistant to infection.
Finally, studies of chronic infections in Haloarcula hispanica uncovered that some viruses can reprogram host cells, altering their shape and gene activity without immediately killing them.
Overall, this research provides new insights into how archaeal viruses infect, persist, and interact with their hosts. By uncovering the factors that determine host range and viral resistance, it lays important groundwork for understanding virus–host dynamics in one of the least explored branches of the microbial world.