Schistosomiasis Vector Snails and Their Microbiota Display a Phylosymbiosis Pattern

Abstract

Planorbidae snails are the intermediate host for the trematode parasite of the Schistosoma genus, which is responsible for schistosomiasis, a disease that affects both humans and cattle. The microbiota for Schistosoma has already been described as having an effect on host/parasite interactions, specifically through immunological interactions. Here, we sought to characterize the microbiota composition of seven Planorbidae species and strains. Individual snail microbiota was determined using 16S ribosomal DNA amplicon sequencing. The bacterial composition was highly specific to the host strain with limited interindividual variation. In addition, it displayed complete congruence with host phylogeny, revealing a phylosymbiosis pattern. These results were confirmed in a common garden, suggesting that the host highly constrains microbial composition. This study presents the first comparison of bacterial communities between several intermediate snail hosts of Schistosoma parasites, paving the way for further studies on the understanding of this tripartite interaction.

The hemolymph ofBiomphalariasnail vectors of schistosomiasis supports a diverse microbiome

“…This locus likely contains immune genes that could specifically shape the whole snail microbiome. In addition, a recent analysis of whole snail microbiomes that included several Biomphalaria species and B. glabrata populations is consistent with our observation regarding species differentiation based on microbiome but failed to support B. glabrata population differentiation [18]. Three factors from the Huot et al [18] study could explain this difference: (i) the shell was removed prior to DNA extraction: this may have resulted in significant loss of hemolymph, reducing the contribution of hemolymph to the results, or (ii) their analysis focused on the core microbiome: excluding rare taxa may have limited their ability to detect population differentiation, or (iii) the composite microbiome from whole snails (including microbiomes from multiple different organs) was analyzed.…”

“…With this relatively limited technique, the authors observed changes in whole snail microbiome when those were moved between different environments [16]. More recently, two papers [17, 18] have examined Biomphalaria spp. microbiomes using deep sequencing of rDNA.…”

“…Allan et al [17] showed that snails carrying alleles conferring resistance to S. mansoni infection, show distinctive microbiomes from those carrying sensitive alleles, suggesting possible links between the microbiome composition and S. mansoni susceptibility. Huot et al [18] examined core microbiomes from several laboratory populations, showing a high specificity between these microbiomes and their snail host populations, as well as complete congruence between core microbiome and host phylogeny. Importantly, both these studies examined microbiomes of whole snails, so it is unclear whether the bacteria characterized are from the gut, shell surface, mantle cavity or internal organs of the snail, each of which may have a distinctive microbiome.…”

The hemolymph of Biomphalaria snail vectors of schistosomiasis supports a diverse microbiome

“…With this relatively limited technique, the authors observed changes in whole snail microbiome when those were moved between different environments (Ducklow et al ., 1979). More recently, two papers (Allan et al ., 2018; Huot et al ., 2020) have examined Biomphalaria spp. microbiomes using deep sequencing of rDNA.…”

A bug’s life: Delving into the challenges of helminth microbiome studies

“…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.…”