Open Collections

Billy, Vincent

University of British Columbia

The intestinal tract of mammals is colonized by a diversity of eukaryotes, including metazoan worms, protists and fungi. Although parasitologists historically identified them as parasites causing diseases, more recent studies suggest they can be commensal or beneficial for the host. Indeed, intestinal eukaryotes can protect against immune-mediated disorders in experimental systems by regulating the host immune system and gut bacterial community and are common in healthy populations. In Chapter 1 (Introduction), I conducted a literature review on the genetic diversity of Blastocystis (classified into 25 subtypes), its host specificity, and its interactions with the gut bacterial community and the host immune system. Previous studies confirm that Blastocystis can cause disease or promote health by regulating the immune system and the gut bacterial community. Variation between studies is linked to various factors, including (i) the host specificity of subtypes and the existence of potential pathogenic subtypes, (ii) the host clinical conditions (IBS, IBD, colitis, …), (iii) Blastocystis duration of colonization and abundance and (iv) co-infections with multiple intestinal eukaryotes. In Chapter 2, using an experimental approach, I demonstrated that Blastocystis subtype 3, a common subtype found in mammals, provided faster recovery against colitis in rats. Recovery was associated with the regulation of the immune system and gut bacterial community and was dependent on the duration of colonization. In Chapter 3, I showed that Blastocystis presence and abundance were associated with the signs of a healthy gut, including higher bacterial diversity, lower levels of pathogenic bacteria and lower levels of gut permeability in stunted and non-stunted children from The Central African Republic and Madagascar. In Chapter 4, I described the intestinal eukaryote community in wild western lowland gorillas and found 40 intestinal eukaryotes. Intestinal eukaryotes were more likely to co-occur, suggesting that they could promote each others’ colonization. Variations in abundance, prevalence and duration of colonization between taxa indicate different levels of host-specificity. My results provide crucial information on the diversity and ecology of intestinal eukaryotes and their potential to regulate the host immune system and gut bacterial community.

Text

2024-07-04

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88572

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/