Serine protease and phenoloxidase activities in hemocytes of Biomphalaria glabrata snails with varying susceptibility to infection with the parasite Schistosoma mansoni

Abstract

The snail Biomphalaria glabrata possesses hemocytes, which are supposed to interact with the larval stages of the human parasite Schistosoma mansoni. We describe trypsin-like serine protease(s) and phenoloxidase activities in lysates from these hemocytes. Both enzymes have activity optima around pH 9.5. The serine protease was inhibited by EDTA, PMSF, antipain and aprotinin, and the phenoloxidase activity by diethydithiocarbamate. By comparison, the serine protease activity in secretions of S. mansoni cercariae also had an alkaline pH optimum around 10.5 and was sensitive to the same inhibitors. In addition, serine protease activities from snails and cercariae had the same molecular mass of 28 kDa. However, the K(m) value of the serine protease(s) and the K(i) values of different inhibitors were generally lower for the snail enzyme than for the cercarial enzyme. The serine protease activity varied among individual snails but activity in hemocyte lysates and hemolymph correlated strongly. There was no detectable difference in the levels of activity between snails which are susceptible or resistant to schistosome infection.

Differences in Cysteine Protease Activity in Schistosoma mansoni-Resistant and -Susceptible Biomphalaria glabrata and Characterization of the Hepatopancreas Cathepsin B Full-length cDNA

“…glabrata interaction. Although previous studies (Bahgat et al, 2002;Mitta et al, 2005) described the presence of several proteolytic enzymes in the snail (aminopeptidase, hydrolase, lysozymes, and genes encoding serine proteases, cathepsin L, and metalloproteases), none described differences (qualitative and quantitative) in activity of these enzymes between parasite resistant and susceptible snails as shown here for cysteine proteinases.…”

“…glabrata interaction. Although previous studies (Bahgat et al, 2002;Mitta et al, 2005) described the presence of several proteolytic enzymes in the snail (aminopeptidase, hydrolase, lysozymes, and genes encoding serine proteases, cathepsin L, and metalloproteases), none described differences (qualitative and quantitative) in activity of these enzymes between parasite resistant and susceptible snails as shown here for cysteine proteinases.Proteolytic enzymes have been detected in both the humoral and cellular components of the snail's innate defense system, the hemolymph and hemocytes, respectively, with levels changing relative to either bacteria or schistosome infections Kassim and Richards, 1978). Granulocytes, a type of hemocyte involved in the cellular encapsulation reaction typically seen in the nonself reaction against incompatible parasites, were shown to express high levels of acid phosphatase activity in a resistant snail upon exposure to S. mansoni miracidia, and they were thus hypothezied by Cheng and Garrabrant (1977) to contribute to parasite destruction mediated by these cells.…”

“…By analyzing the segregation of susceptibility phenotypes with different enzyme markers (aconitase, acid phospatase, esterase, leucylglycylglycine peptidase, and 6-phoshogluconate dehydrogenase), Mulvey and Woodruff (1985) were unable to find linkage with these markers and the resistance phenotype. A recent study that showed the presence of serine protease activity in B. glabrata snails (hemocytes) also failed to find an association with this enzyme and variations in the snail's susceptibility phenotype (Bahgat et al, 2002). In the literature, certain snails have been described as being "unsuitable" for schistosome infection.…”

Activation of the immune defence of the freshwater snailLymnaea stagnalisby different immune elicitors

“…Both of them are important components of immune defence in invertebrates including molluscs (e.g. Allam et al, 2006;Bahgat et al, 2002;Butt and Raftos, 2008;Hellio et al, 2007;Hernroth, 2003;Mitta et al, 2000;Muñoz et al, 2006). We snap-froze the haemolymph samples in liquid nitrogen [10μl of haemolymph mixed with 100μl of phosphate buffered saline (PBS; pH7.4) for PO activity assay, and 70μl of pure haemolymph for antibacterial activity assay], and stored them at −80°C.…”

Histopathological study on susceptible and resistant Bulinus truncatus snails to infection with Schistosoma haematobium

“…E-mail: kah201017@yahoo.com. primary effectors of the snail defense system and its resistance lies in the ability of circulating hemocytes to recognize and bind the parasite surface and then undergo a cytotoxic activation, resulting in the effective killing of the parasite (Matricon-Gondran and Letocart, 1999;Bahgat et al, 2002;Martins-Souza et al, 2006). Some gene combinations allow the parasite to develop and proliferate because the snail fails to recognize it as foreign.…”