Participation of N-acetyl-D-glucosamine carbohydrate moieties in the recognition of Schistosoma mansoni sporocysts by haemocytes of Biomphalaria tenagophila

Abstract

Lectin-carbohydrate binding may be involved in the recognition of Schistosoma mansoni sporocysts by haemo-cytes of Biomphalaria; therefore, we tested if this interaction is associated with snail resistance against Schistosoma infection. In vitro data showed that most of the S. mansoni sporocysts cultured with haemocytes from Biomphalaria glabrata BH, a highly susceptible snail strain, had a low number of cells that adhered to their tegument and a low mortality rate. Moreover, the addition of N-acetyl-D-glucosamine (GlcNAc) did not alter this pattern of adherence and mortality. Using haemocytes and haemolymph of Biomphalaria tenagophila Cabo Frio, we observed a high percentage of sporocysts with adherent cells, but complete encapsulation was not detected. Low concentrations of GlcNAc increased haemocyte binding to the sporocysts and mortality, which returned to basal levels with high concentrations of the carbohydrate. In contrast, haemocytes plus haemolymph from B. tenagophila Taim encapsulated cellular adhesion index of level 3 and destroyed over 30% of the S. mansoni sporocysts in culture. Interestingly, the addition of GlcNAc, but not mannose, to the culture medium resulted in the significant inhibition of cellular adhesion to the parasite tegument and the reduction of parasite mortality, suggesting that GlcNAc carbohydrate moieties are important to the recognition of S. mansoni by B. tenagophila Taim.

Resistance of Biomphalaria glabrata 13-16-R1 snails to Schistosoma mansoni PR1 is a function of haemocyte abundance and constitutive levels of specific transcripts in haemocytes

“…Considerable advances have been made toward this goal (Bayne, 2009; Loker, 2010; Moné et al, 2010; Martins-Souza et al, 2011; Hanington et al, 2012; Mitta et al, 2012; Negrão-Corrêa et al, 2012; Blouin et al, 2013; Ittiprasert et al, 2013), yet for both the recognition and the effector phases of the snails’ defence responses, much remains to be learned. Among known facts are that snail size can influence infectivity rates: some strains of B. glabrata are susceptible as juveniles but resistant as adults (Richards et al, 1992), and larger snails exposed to S. mansoni have lower infection levels than smaller snails of the same age (Niemann and Lewis, 1990).…”

“…This change is most intense in resistant snails in which larger haemocytes nearly disappear from the haemolymph, while small cells gradually increase (Martins-Souza et al, 2009). Haemocytes are involved in parasite recognition (Negrão-Corrêa et al, 2012), a capability that involves carbohydrate-binding receptors on spreading haemocytes (Fryer et al, 1989; van der Knaap and Loker, 1990; Renwrantz and Richards, 1992; Johnston and Yoshino, 2001; Castillo et al, 2007; Martins-Souza et al, 2011; Mitta et al, 2012). These cells are phagocytic granulocytes and, in resistant snails, they encapsulate schistosomes and the parasites are killed.…”

Breeding of Biomphalaria tenagophila in mass scale

“…This strain is absolutely resistant to S. mansoni, and has been the subject of various studies 1,5,6,13,17,18,19,20,25,27 . Among these studies, the model for the biological control of schistosomiasis transmission is highlighted.…”

Interaction ofSchistosoma mansoniSporocysts and Hemocytes ofBiomphalaria

“…However, there is experimental evidence that soluble elements of the hemolymph participate in the protective mechanism against pathogens in many invertebrates [24–27]. Soluble components of the hemolymph can interact directly with pathogenic agents producing toxic substances or lytic peptides, or indirectly through mediator molecules for recognition of the pathogen or hemocyte activators [22, 28–32]. In Biomphalaria , hemocytes circulating in hemolymph or fixed in tissues are mainly produced by a well-defined region located between the pericardium and the posterior epithelium of the mantle cavity, called the amebocyte producing organ (APO) [33].…”