Division of Blastocystis ST10 into Three New Subtypes: ST42-ST44

The Blastocystis subtype ST10 has been recognized to contain a great deal of diversity at the sequence level, potentially indicating the presence of multiple new STs within the clade. However, the data needed to validate these new STs were not available. To help resolve this diversity, full-length small subunit (SSU) rRNA gene reference sequences were generated using Oxford Nanopore MinION long-read sequencing from 21 samples representing multiple domestic and wild hosts and geographic regions and covering the sequence diversity previously described using fragments of the SSU rRNA gene. Phylogenetic and pairwise distance analyses were used to compare full-length sequences of the SSU rRNA gene generated in this study with all other valid STs of Blastocystis. We present data supporting the division of ST10/ST23 cluster into five subtypes, ST10, ST23, and three new subtypes with the proposed ST designations of ST42, ST43, and ST44. As the host range of Blastocystis continues to expand with new subtypes and new hosts being frequently identified, the reference sequences provided in this study will assist in accurate sequence classification and help to clarify the epidemiology of this common intestinal microeukaryote.