Division of Blastocystis ST10 into three new subtypes: ST42-ST44

Authors: Santin-Duran, Monica; FIGUEIREDO, ANA - University Of Aveiro (UA); Molokin, Aleksey; George, Nadja; KOSTER, PAMELA - Instituto De Salud Carlos Iii; DAHSTI, ALEJANDRO - Instituto De Salud Carlos Iii; GONZALEZ-BARRI, DAVID - Instituto De Salud Carlos Iii; CARMENA, DAVID - Instituto De Salud Carlos Iii; Maloney, Jenny

Submitted to: Journal of Eukaryotic Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/2023
Publication Date: 9/1/2023
Citation: Santin, M., Figueiredo, A., Molokin, A., George, N.S., Koster, P.C., Dahsti, A., Gonzalez-Barri, D., Carmena, D., Maloney, J.G. 2023. Division of Blastocystis ST10 into three new subtypes: ST42-ST44. Journal of Eukaryotic Microbiology. 71(1): e12998. https://doi.org/10.1111/jeu.12998.
DOI: https://doi.org/10.1111/jeu.12998

Interpretive Summary: Blastocystis is a common intestinal parasite of humans and many other animals. Genetic diversity within the genus is high with 41 subtypes (STs) identified based on sequence level differences in the small subunit (SSU) rRNA gene. The Blastocystis subtype ST10 has been identified as potentially encompassing multiple STs. However, the data needed to validate these new STs was not available. To help resolve this diversity, full-length 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. Comparison of sequences via phylogenetic and pairwise distance analyses were performed using the full-length sequences of the SSU rRNA gene generated in this study and all other valid STs of Blastocystis. The data from this study support the division of the genetic cluster containing ST10 and ST23 into five subtypes, ST10, ST23, and three new subtypes with the proposed ST designations of ST42, ST43, and ST44. The host range of Blastocystis continues to expand with new subtypes and new hosts being frequently identified. The reference sequences produced in this study are essential for accurate sequence classification and will help to clarify the epidemiology of this common intestinal microeukaryote.

Technical Abstract: 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 was 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.