Mapping of the conserved antigenic domains shared between potato apyrase and parasite ATP diphosphohydrolases: potential application in human parasitic diseases

Abstract

Evolutionary and closer structural relationships are demonstrated by phylogenetic analysis, peptide prediction and molecular modelling between Solanum tuberosum apyrase, Schistosoma mansoni SmATPase 2 and Leishmania braziliensis NDPase. Specific protein domains are suggested to be potentially involved in the immune response, and also seem to be conserved during host and parasite co-evolution. Significant IgG antibody reactivity was observed in sera from patients with American cutaneous leishmaniasis (ACL) and schistosomiasis using potato apyrase as antigen in ELISA. S. mansoni adult worm or egg, L. braziliensis promastigote (Lb) and Trypanosoma cruzi epimastigote (EPI) have ATP diphosphohydrolases, and antigenic preparations of them were evaluated. In ACL patients, IgG seropositivity was about 43% and 90% for Lb and potato apyrase, respectively, while IgM was lower (40%) or IgG (100%) seropositivity for both soluble egg (SEA) and adult worm (SWAP) antigens was higher than that found for potato apyrase (IgM=10%; IgG=39%). In Chagas disease, IgG seropositivity for EPI and potato apyrase was 97% and 17%, respectively, while the IgM was low (3%) for both antigens. The study of the conserved domains from both parasite proteins and potato apyrase could lead to the development of new drug targets or molecular markers.

Immunostimulatory property of a synthetic peptide belonging to the soluble ATP diphosphohydro-lase isoform (SmATPDase 2) and immunolocalisation of this protein in the Schistosoma mansoni egg

“…By in silico analysis, a closer structural relationship was described between this vegetable protein and SmATPDase 2, a soluble ATP diphosphohydrolase isoform described in the S. mansoni adult worm. Specific conserved domains were suggested to be potentially involved in the immune response (Faria-Pinto et al 2008). In an attempt to detect the immune potential of a specific protein domain in studies of schistosomiasis, the synthetic peptide SmB2LJ was obtained.…”

“…A peptide (SmB2LJ; r175-194; AALSLTKLINIAETSLPVDV) belonging to a conserved domain from soluble S. mansoni SmATPDase 2 (GenBank accession ABI79456.1) was designed based on a strategic comparative study with its potato apyrase counterpart (r97-116; AANSLEPLLDGAE-GVVPQEL; 40% identity and 65% similarity over 20 amino acids) (GenBank accession P80595), which maintained the predicted epitopes available for antibody binding (Faria-Pinto et al 2008). The amino acid sequence of SmB2LJ peptide has lower identity (20-30%) and similarity (40-55%) with its S. mansoni SmATPDase 1 (accession AAP94734) counterpart or with amino acid sequence of either S. mansoni GDPase (CAZ35542.1), mouse NTPDase 5 (NP_001021385.1) or mouse NTPDase 6 (NP_742115.2) counterpart.…”

“…This finding was in accordance with the existence of antigenic domains within these parasite ATP diphosphohy-A peptide (SmB2LJ; drolase isoforms, as these epitopes are shared with those from vegetable proteins (Faria-Pinto et al 2004, 2010a. Domains of high identity between potato apyrase and the S. mansoni SmATPDase 2 were observed by alignment of their primary amino acid sequences and by hypothetical three-dimensional models, suggesting that these conserved domains may be exposed and available for antibody binding (Faria-Pinto et al 2008, Vasconcelos et al 2009). …”

Detection of IgG1 and IgG4 subtypes reactive against potato apyrase in schistosomiasis patients

“…mansoni ATP diphosphohydrolase was characterised in soluble egg antigens (Faria-Pinto et al 2004). Recently, using in silico analysis, we showed that potato apyrase and parasites ATP diphosphohydrolase isoforms, which are members of the same proteins family, have domains shared among them that are predicted to be rich in B-cell epitopes (Faria-Pinto et al 2008, Vasconcelos et al 2009). We hypothesised that different antigenic epitopes shared between potato apyrase and S. mansoni ATP diphosphohydrolase isoforms could be involved in susceptibility or resistance to S. mansoni AT.…”

“…The total IgG, IgG1 and IgG4 antibody reactivities against potato apyrase were evaluated by ELISA, using potato apyrase (5 µg) as coating antigens and serum samples diluted 1:50-1:400, as previously described (Faria-Pinto et al 2008), peroxidase-conjugated anti-IgG, anti-IgG1 or anti-IgG4 human-specific immunoglobulin antibodies (PharMingen, Sand Diego, CA) and O-phenylenediamine dihydrochloride/H 2 O 2 as the substrate. The total IgG reactivity (0.246 ± 0.186) for potato apyrase in serum samples diluted 1:200 from 49 schistosomiasis pa- Key words: Schistosoma mansoni -ATP diphosphohydrolase -potato apyrase tients from Penha do Cassiano was significantly higher (p < 0.01) than that found in healthy individuals (0.080 ± 0.030; cut-off 0.140) and 30 (61%) of them demonstrated seropositivity for this vegetable protein (Fig.…”