Year: 2020
Type: review
Abstract: The body of vertebrates is inhabited by trillions of microorganisms, i.e., viruses, archaea, bacteria, and unicellular eukaryotes, together referred to as the "microbiota."Similarly, vertebrates also host a plethora of parasitic worms (the "macrobiota"), some of which share their environment with the microbiota inhabiting the gastrointestinal (GI) tract [1].Complex interactions between the helminths and the gut microbiota have been associated with establishment of parasite infection, disease manifestations, and host immune-modulation [2, 3].Remarkably, not only GI helminths alter the gut microbiome composition [4], but also the infections with blood flukes of the genus Schistosoma have been associated with intestinal dysbiosis, that even occurs before the onset of egg laying [5,6].Comparably, over the last decade, evidence has emerged of the contribution(s) of the resident microbiota to several physiological and reproductive processes of invertebrate hosts, including insects, arachnids, worms, and snails [7,8].These noteworthy discoveries, coupled with the recent expansion of high-throughput microbiota-and microbiome-profiling approaches (the former referring to the community of microorganisms themselves and the latter to the microorganisms and their genomes, within a given ecological niche), are rapidly leading to a much better understanding of the composition and functions of microbial communities inhabiting parasitic worms of major public health and socioeconomic significance.This basic knowledge might expose exploitable vulnerabilities of parasites, thus paving the way to the development of novel control strategies [9].In this Viewpoint, we consider the challenges associated with the study of the helminth microbiota/-me, spanning not only bacteria transiently associated with parasites in which the life cycle includes free-living and parasitic stages, but also putative helminth endosymbionts.Indeed, endosymbionts have been described in both roundworms and flatworms [10,11].In nematodes, the most notable example of a mutualistic relationship between worms and bacteria is represented by filarial parasites [12], i.e., Onchocerca volvulus, Wuchereria bancrofti, and Brugia malayi, agents of human lymphatic filariasis.In particular, the fitness, propagation, and survival of these worms depend on endosymbiotic bacteria of the genus Wolbachia that have thus become the target of intense research aimed to develop novel filaricidal compounds [11,13].On the other hand, bacteria of the genus Neorickettsia have been identified in the endoparasitic digeneans, i.e., trematodes [10].These intracellular bacteria inhabit the worm reproductive tissues and are vertically-transmitted to the next generation of parasites via the eggs [10].In addition, horizontal transmission of Neorickettsia from the fluke to the fluke-infected vertebrate host, where the bacteria colonize macrophages among other cell types, is a determinant
Source: PLoS neglected tropical diseases
Language: English
Subfield: Parasitology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,350
Funders: Wellcome Trust, Ministero della Salute
OpenAlex ID: W3043142121