Selective Interference with Granulocyte Function Induced by Echinostoma paraensei (Trematoda) Larvae in Biomphalaria glabrata (Mollusca)

Abstract

Various trematode larvae can interfere with the host snail's resistance to the same or unrelated trematode species, chiefly, it appears by interference with the function of the host's granulocytes. In Biomphalaria glabrata infected with the trematodes, Echinostoma paraensei, granulocytes lose their ability to encapsulate the larvae of trematodes to which the hosts were previously resistant. However, the granulocytes in these snails retain their ability to encapsulate injected latex spheres, or larvae of the metastrongyle nematode, Angiostrongylus malaysiensis, and to phagocytose epidermal plates cast off by miracidia of the trematode, Schistosoma mansoni. Cellular infiltration in injured preputial tissue of the snail also was not suppressed by the presence of E. paraensei larvae. Interference with the granulocyte function in B. glabrata induced by E. paraensei infection therefore appears to be a selective phenomenon.

Differential transcriptomic responses of Biomphalaria glabrata (Gastropoda, Mollusca) to bacteria and metazoan parasites, Schistosoma mansoni and Echinostoma paraensei (Digenea, Platyhelminthes)

“…Previously, Zhang et al (2008b) also observed decreased expression of FReM after E. paraensei infection. This strong trend of down-regulation of transcripts involved in host defense lends support to the hypothesis that E. paraensei actively interferes with the snail immune response (Lie et al, 1981; Loker et al, 1986; Loker et al, 1992). …”

“…Some strains of B. glabrata are resistant to S. mansoni (Lie et al, 1979), and this remains an important topic for exploration (Bayne, 2009), as it may lead to novel methods of interrupting transmission of human schistosomaisis. Trematodes actively undertake efforts to avoid immune elimination by host defenses (Lie et al, 1981; Loker and Adema, 1994). Accordingly, gene expression profiles recorded from trematode infected snails will reflect an amalgam of anti-pathogen defense efforts mounted by the snail and of parasite-directed modifications of expression of host genes that may function in defense or other aspects of homeostasis.…”

Influence of Trichobilharzia regenti (Digenea: Schistosomatidae) on the Defence Activity of Radix lagotis (Lymnaeidae) Haemocytes

“…Furthermore, within haemocytes we observed microtubular aggregates that likely corresponded to the remnants of phagocytosed ciliary plates. Ciliary plates of S. mansoni miracidia are also phagocytosed by B. glabrata haemocytes [34].…”

Symptoms of behavioural anapyrexia – Reverse fever as a defence response of snails to fluke invasion

“…Research on Gastropods' defence reactions is almost entirely devoted to interactions in the snail-trematode system (Lie et al, 1981;Bayne and Yoshino, 1989;Loker et al, 1989;Fryer and Bayne 1990;Amen et al, 1991;Yoshino and Vasta, 1996;Adema and Loker, 1997;Horak and Van der Knaap, 1997;Sapp and Loker, 2000; see review : Loker, 2010), but the concentration of researchers on the cellular and humoral processes in snails means that relatively little is known of the ability of snails to generate nonspecific reactions, analogous to fever, which may follow a similar course in all animals. Independent of the systematic position, many ectotherms developed a behavioural mechanism for changing body temperature, involving moving to warmer or cooler microhabitats (Portner 2002;Zippay et al, 2004).…”