We Know Almost Nothing About Giant Viruses
Giant viruses are mysteriously large & complex. We still don’t know much about what giant viruses do, other than kill amoebas & algae. But giant viruses don’t just kill their hosts. In some cases, they can keep their hosts alive & become part of them.

https://www.theatlantic.com/science/archive/2021/01/giant-viruses-can-change-their-hosts-dna/617555/