Systematic analysis of intracellular replication competence of mammalian, avian, and reptilian kolmioviruses.

Kolmioviruses (KoVs) are single-stranded RNA viruses that may have evolved through host switching between different vertebrate classes. However, the specific host compatibility of their intracellular replication has not been well-studied. In this investigation, researchers examined six mammalian, one avian, and one reptilian KoV using cell lines from the same three vertebrate classes.

They introduced plasmids containing 1.2 times the length of the KoV genome into the cells and monitored the presence of delta antigen over a period of up to 18 days to assess persistent replication.

The results showed that four mammalian KoVs replicated only in mammalian cell lines, while the avian and reptilian KoVs replicated exclusively in both avian and reptilian cell lines. Interestingly, the remaining two mammalian KoVs, which belong to a clade with deeper lineages in both avian and reptilian KoVs, replicated persistently in all three cell line types. These patterns of persistent replication align with the phylogenetic grouping of the KoVs.

The findings suggest an evolutionary scenario in which the common ancestor of the two mammalian KoVs within the avian-reptilian clade acquired the ability to replicate in mammalian cells while still retaining its capacity to infect avian and reptilian hosts. This transition could have played a role in the eventual adaptation of this lineage to mammalian hosts.