A peptide (SmB2LJ; r175-194) that belongs to a conserved domain from Schistosoma mansoni SmATPDase 2 and is shared with potato apyrase, as predicted by in silico analysis as antigenic, was synthesised and its immunostimulatory property was analysed. When inoculated in BALB/c mice, this peptide induced high levels of SmB2LJ-specific IgG1 and IgG2a subtypes, as detected by enzyme linked immunosorbent assay. In addition, dot blots were found to be positive for immune sera against potato apyrase and SmB2LJ. These results suggest that the conserved domain r175-194 from the S. mansoni SmATPDase 2 is antigenic. Western blots were performed and the anti-SmB2LJ antibody recognised in adult worm (soluble worm antigen preparation) or soluble egg antigen antigenic preparations two bands of approximately 63 and 55 kDa, molecular masses similar to those predicted for adult worm SmATPDase 2. This finding strongly suggests the expression of this same isoform in S. mansoni eggs. To assess localisation of SmATPDase 2, confocal fluorescence microscopy was performed using cryostat sections of infected mouse liver and polyclonal antiserum against SmB2LJ. Positive reactions were identified on the external surface from the miracidium in von Lichtenberg's envelope and, in the outer side of the egg-shell, showing that this soluble isoform is secreted from the S. mansoni eggs

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Gall induction, mediated by insect-herbivore chemical stimuli, is the result from anatomical and biochemical alterations in the host-plant tissues that provides shelter, food and defence against natural enemies and the harsh environment to the gall inducer. Schizomya macrocapillata Maia (Diptera, Cecidomyiidae) induces galls on Bauhinia brevipes Vogel (Fabaceae); the galls are spherical, with long reddish hairs that cover the adaxial wall surface of the gall, and a protuberance is observed on the abaxial leaf surface. Some plants are resistant to gall formation and, in many cases, this formation is inhibited by hypersensitive reaction. In the present work, samples from different parts of the non-galled and galled tissues from resistant and susceptible plants were carefully dissected. Indicating elevated metabolic activity, the protein concentration was 1.5–4.5-fold higher in the abaxial portion of the galls than in any other tissues, regardless of whether the galls were from resistant or susceptible plants. Different tissues from susceptible and resistant plants had distinct protein concentrations, and the fractionation of the proteins by SDS–PAGE and silver-staining showed shared and/or specific polypeptides. We hypothesise that specific proteins, possibly from distinct metabolic pathways, are involved in the physiological processes that determine whether the plant shows total and/or partial host resistance to the galling-insect attack.

NTPDases are enzymes that hydrolyse diphosphate and triphosphate nucleosides, regulating purinergic signalling in many organisms. The Schistosoma mansoni NTPDases, SmATPDases 1 and 2, are antigenic proteins and display a significant homology with the isoforms found in mammalian cells. In this work, we investigated whether anti-SmATPDase antibodies from S. mansoni-infected mice sera show cross-reactivity with the NTPDase 1 isoform from macrophages and how this event affects the cell proliferation. By Western blot, anti-SmATPDase antibodies present in serum from infected mice recognized 2 bands with approximately 53 and 58 kDa, corresponding to NTPDase 1. Additionally, the enzyme was identified in macrophages by immunofluorescence and the anti-SmATPDase antibodies were able to reduce activity enzyme (22%). Macrophages incubated with commercial polyclonal antibodies reactive with NTPDase 1 (anti-CD39) showed a reduction of 40% of the enzyme activity. In proliferation assays, macrophage proliferation was inhibited 11% and 90% by pooled sera from infected animals and anti-CD39, respectively. The results suggest that inhibition of NTPDase 1 in macrophages by antibodies produced against the isoforms of the S. mansoni ATPDases could be a mechanism of regulation in the immune response during experimental schistosomiasis.

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