Interaction ofSchistosoma mansoniSporocysts and Hemocytes ofBiomphalaria

Abstract

<jats:p>Human infection by<jats:italic>Schistosoma mansoni</jats:italic>affects more than 100 million people worldwide, most often in populations of developing countries of Africa, Asia, and Latin America. The transmission of<jats:italic>S. mansoni</jats:italic>in human populations depends on the presence of some species of<jats:italic>Biomphalaria</jats:italic>that act as an intermediate host. The compatibility between<jats:italic>S. mansoni</jats:italic>and its intermediate host is influenced by behavioral, physiological, and genetical factors of the mollusc and the parasite. The susceptibility level of the mollusc has been attributed to the capacity of internal defense system (IDS)—hemocytes and soluble components of the hemolymph—to recognize and destroy the parasite, and this will be the center of interest of this paper. The schistosome-resistant<jats:italic>Biomphalaria</jats:italic>can be an alternative strategy for the control of schistosomiasis.</jats:p>

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.…”

Molecular approach for detecting early prepatent Schistosoma mansoni infection in Biomphalaria alexandrina snail host

“…Although campaigns for schistosomiasis control based on chemotherapy have reduced the morbidity and prevalence of this disease, transmission usually persists to a greater or lesser extent after delivery of treatment because of continuing local transmission and exposure to reinfection (Fenwick 2006;Satayathum et al 2006). The transmission of S. mansoni in human populations has been associated with environmental and socioeconomic conditions, but the presence of susceptible Biomphalaria, is essential (Negrao-Correa et al 2012).…”

Ultrastructural characterization of cells in primary cultures from different adult tissues of Biomphalaria tenagophila TAIM, a strain that is absolutely resistant to Schistosoma mansoni infection

“…Among the eleven species of Biomphalaria described in Brazil, only three have been found infected by S. mansoni in nature: Biomphalaria glabrata (Say, 1818), Biomphalaria tenagophila (Orbigny, 1835) and Biomphalaria straminea (Dunker, 1848). B. tenagophila is the second most important for schistosomiasis transmission in the country, especially in the South and Southeast regions [Paraense, 2001;Caldeira et al, 2009;Negrão-Corrêa et al, 2012].…”