Analysis of Circulating Haemocytes fromBiomphalaria glabratafollowingAngiostrongylus vasorumInfection Using Flow Cytometry

Abstract

Angiostrongylus vasorum is an emerging parasite of dogs and related to carnivores that have an indirect life cycle, with a wide range of terrestrial and aquatic gastropods as the obligatory intermediate host. Unfortunately, the relationship between A. vasorum and their snail hosts remains poorly understood. Circulating haemocytes are the main line of cellular defence involved in the destruction of helminths in snails. Aiming to further characterize the haemocyte subsets in Biomphalaria snails, we have performed a flow cytometric analysis of whole haemolymph cellular components using a multiparametric dual colour labelling procedure. Our findings demonstrated that B. glabrata infected with A. vasorum have two major circulating haemocyte subsets, referred to as small and large haemocytes. Differences in the cell proportion occurred over time. The development of better invertebrate infection control strategies would certainly result in the better control of human diseases caused by other species of the genus Angiostrongylus. Such knowledge will assist in the establishment of novel control strategies aimed at parasites that use molluscs as intermediate hosts and clarify new aspects of the parasite-host relationship regarding cell recognition and activation mechanisms, which are also found in the innate response of vertebrates.

Larval development of the cat lungworm Aelurostrongylus abstrusus in the tropical freshwater snail Biomphalaria glabrata

“…On the other hand, we cannot rule out the possibility that the absence of larvae at 28 wpe in B. glabrata Table 1 was due to spontaneous departure of L3 from the snails, as it has been demonstrated for the same snail species infected with Angiostrongylus vasorum, another metastrongyloid nematode (Barcante et al 2003), or in H. aspersa infected with A. abstrusus (Giannelli et al 2015). Due to its high fertility and easy maintenance, Biomphalaria glabrata is not only a naturally occurring intermediate host but also a perfect experimental intermediate host for S. mansoni (DeJong et al 2001;Pointier et al 2005), and proved its suitability for experimental infections also with other metastrongylid parasites such as A. vasorum (Ash, 1970;Barcante et al 2012). The findings presented here describe in detail the development of A. abstrusus from L1 to L3 and the development rate in B. glabrata.…”

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

“…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). Circulating snail haemocytes play a key role in immune surveillance (Oliveira et al, 2010) and will migrate from the haemolymph into the tissues after parasitic infection (Noda and Loker, 1989; Martins-Souza et al, 2009; Barçante et al, 2012). 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).…”

Hemocyte subpopulation changes in Bithynia snails infected with Opisthorchis viverrini in Thailand.

“…Experimental studies have emphasized the positive effect of parasitic infections on the number of hemocytes in the hemolymph of various species (McReath et al, 1982;Bezerra et al, 1997;Ordas et al, 2000;Oliveira et al, 2010;Santos et al, 2011;Barcante et al, 2012). Furthermore, differences in the cell proportion occur often.…”

“…At the onset of infection, the small cells (agranulocytes) change into granulocytes, which have a large size, numerous cytoplasmic inclusions and long pseudopodia (van der Knaap and Meuleman, 1986;van der Knaap et al, 1993;Gorbushin and Iakovleva, 2006). These granulocytes are effector cells that migrate to the infection site, thus the number of granulocytes in the hemolymph decreases (Bezerra et al, 1997;Santos et al, 2011;Barcante et al, 2012).…”