Nuclear group I introns in the 18S rDNA subtypes of Vermamoeba vermiformis

Vermamoeba vermiformis is a widespread free-living amoeba, playing a major role as a host of pathogens and probably acting as an opportunistic parasite. Identification is usually done by targeting the 18S rRNA gene which is highly conserved between different strains. In this study, the main sublines and subtypes of the amoeba were identified by molecular phylogeny of nearly complete sequences and by analysis of secondary structure. Complete analysis of the available sequences showed the presence of two heterologous introns in seven strains of Vermamoeba belonging to three distinct sublines. One strain has a conventional S788 intron, the others harbor an S943 intron with degenerated endonucleases. The two introns are phylogenetically related and show a common origin with an intron identified in Clandestinovirus, a giant virus infecting Vermamoeba. Current data suggests that these elements are part of a more diverse group that spreads horizontally in various hosts.

Automated summary

The study identified the main sublines and subtypes of Vermamoeba amoeba through molecular phylogeny and secondary structure analysis, revealing the presence of two heterologous introns in seven strains. These introns are phylogenetically related and share a common origin with an intron found in a giant virus infecting Vermamoeba, suggesting they are part of a more diverse group that spreads horizontally in various hosts.