Compatibility of Biomphalaria tenagophila with Schistosoma mansoni: a study of homologous plasma transference

Abstract

This study aims to investigate the importance of the serum factors present in the plasma of resistant Biomphalaria tenagophila snails, when transferred to susceptible conspecific. Susceptible B. tenagophila (CF) received plasma from resistant B. tenagophila (Taim), and both were later infected with Schistosoma mansoni. We noticed that the plasma transfer showed an increase on the resistance of susceptible snails of about 86% when compared to the nonimmunized group (p < 0.001).Key words: Biomphalaria -Schistosoma mansoni -plasma Among the endogenous factors involved in snailtrematode interaction, the most important is in relation to the gastropods defense system. This system is different from the vertebrate immune system, as the lymphocytes, immunoglobulins specific antigen are lacking. Nevertheless, the differentiation between the "self" and the "not self" is kept (Bayne 1983). The defense system is made by cellular and humoral elements. The cellular defense system is operated by hemocytes (moving cells), which have phagocytic capacity. The humoral immunity is measured by lectins and opsonins, which are proteins synthesized by hemocytes with specific affinities with carbohydrates (Zelck et al. 1995). Bayne et al. (1980) showed the serum transfer effect of resistant Biomphalaria glabrata on the increase of phagocytic capacity of hemocytes from susceptible snails, demonstrative of interaction between plasmatic factors and the hemocytes during the encapsulation and phagocytic process, that occurred few hours after the miracidium penetration. Although the model B. glabrata/S. mansoni has been the object of several studies, the association B. tenagophila/S. mansoni is also a very interesting model because it shows absolute resistance of the snail to the parasite (Coelho et al. 2004). The aim of this study was to evaluate the occurred changes after plasma transference from resistant to susceptible B. tenagophila snails following infection with Schistosoma mansoni.All snails used came from Brazil. sically the same used by Granath and Yoshino (1984), with minor changes, briefly: all B. tenagophila Taim and Cabo Frio strains were anesthetized with sodic pentobarbitol (Nembutal®), 100 mg/2ml) (Martins-Sousa et al. 2001), for 6 h, to relax all the musculature. The plasma for the transference was collected from a hemolymph pool of five B. tenagophila -Taim snails. After centrifugation of 80 g for 10 min to remove all the hemocytes, it was diluted in sterile PBS in 1:2 proportion. The B. tenagophila -Cabo Frio were inoculated with 5 µl of the diluted serum in the cephalopodal region using a 25 µl Hamilton Microliter® syringe. The control groups B. tenagophila (Taim and Cabo Frio) received the same volume of sterile PBS. Twenty-four hours later, the three groups were individually infected with ten S. mansoni miracidia. Six hours later, the groups were replaced in separate aquariums with aeration by pumping and fed with lettuce ad libitum. All the groups were once a week analyzed concerning the cercarial release up to 60 days ...

Schistosoma mansoni in Susceptible and Resistant Snail Strains Biomphalaria tenagophila: In Vivo Tissue Response and In Vitro Hemocyte Interactions

“…For example, S. mansoni is unable to elicit infection in the Taim strain of B. tenagophila under laboratory conditions [4] – [7] . This resistance is the result of the internal defense system (IDS) of the mollusk [8] . By contrast, the Cabo Frio strain of B. tenagophila is susceptible to S. mansoni .…”

Phylogenetic analysis of Biomphalaria tenagophila (Orbigny, 1835) (Mollusca: Gastropoda)

“…1979, Bezerra et al 2003, Rosa et al 2004, Coelho & Bezerra 2006. Several studies have been carried out in order to gain a better understanding of resistance traits, including molecular approaches using nuclear DNA regions (Pires et al 1997, Spatz et al 1999, Barbosa 2001, Rosa et al 2005, Barbosa et al 2006), but little is known about the genes related with the resistance phenotype in this population (Santos et al 1979, de Freitas et al 1985, Rosa 2002.…”

Participation of cell‐free haemolymph of Biomphalaria tenagophila in the defence mechanism against Schistosoma mansoni sporocysts

“…The importance of the soluble factors of haemolymph for the protection mechanism against S. mansoni infection was previously demonstrated by Granath and Yoshino (10) and by Coelho and Bezerra (11). The authors reported a decrease in S. mansoni infection rate of B. glabrata PR and B. tenagophila Cabo Frio that were simultaneously inoculated with cell‐free haemolymph from resistant snail strain.…”

“…Granath and Yoshino (10) reported that susceptible strain of B. glabrata (PR) previously inoculated with cell‐free haemolymph from resistant snails (10‐R2) had lower infective rate after exposure to S. mansoni miracidia. A reduction in S. mansoni infective rate was also reported in B. tenagophila Cabo Frio inoculated with cell‐free haemolymph recovered from B. tenagophila Taim, the parasite resistant snail strain (11). Moreover, Vasquez and Sullivan (12) showed that cell‐free haemolymph collected from susceptible B. glabrata previously implanted with the APO from resistant snail strain donors were able to lower the infective rate of S. mansoni in the recipients, suggesting that haemocytes from APO implant were able to secrete soluble factors that participate in the parasite control mechanism.…”