Polymorphic Mucin-Like Proteins in Schistosoma mansoni, a Variable Antigen and a Key Component of the Compatibility Between the Schistosome and Its Snail Host

Abstract

The arms race between vertebrate hosts and parasites has led to diversification systems able to generate huge repertoires of immune recognition receptors and antigenic variants. Until recently, the invertebrate immunity was considered to be poorly specific, and consequently, antigenic variability was not expected to be high for their respective parasites. In the present chapter, we show how the study of the interaction between the snail Biomphalaria glabrata and its parasite Schistosome mansoni has shaken this paradigm. We show that the fate of the interaction between the snail and its parasite is at least partly the result of the concordance of highly variable repertoires of immune recognition receptors in the snail and corresponding antigenic variants in the parasite. We call these antigenic variants of the schistosome Schistosoma mansoni polymorphic mucins (SmPoMucs). We show that their high level of diversification is the result of a complex cascade of mechanisms, thus presenting evidence for antigenic variation in a parasite infecting an invertebrate species.

Physiology and immunity of the invasive giant African snail, Achatina (Lissachatina) fulica, intermediate host of Angiostrongylus cantonensis

“…These interactions play out in a continuous arms race that drives evolution of (mechanisms that generate) diversity and polymorphism of the factors that determine the outcome of the host-parasite interplay (Combes, 2000;Gourbal et al, 2015). For instance, antigenic variation is a common strategy of eukaryote pathogens to evade a host immune response (Finlay and McFadden, 2006;Perrin et al, 2013).…”

Genomic and transcriptional analysis of genes containing fibrinogen and IgSF domains in the schistosome vector Biomphalaria glabrata, with emphasis on the differential responses of snails susceptible or resistant to Schistosoma mansoni

“…With respect to arriving at a mechanistic understanding of snail susceptibility or resistance, it is known that S . mansoni has a large repertoire of genes encoding polymorphic mucin molecules (SmPoMucs) [ 45 ]. Given that these are displayed on the surface of sporocysts, it has been argued that particular combinations of expressed FREPs and SmPoMucs act as determinants of compatibility, thus providing an allele vs. allele matching system that can also help to explain the specificity of compatibility [ 46 ].…”