title: Schistosoma mansoni glyceraldehyde 3-phosphate dehydrogenase is a lung-stage schistosomula surface membrane antigen.
abstract: We have previously reported that Schistosoma mansoni larvae emerging from host lung at pH 7.5-7.8 and then fixed with diluted formaldehyde (HCHO) readily bind radiation-attenuated cercariae (RA) vaccine serum antibodies, as assessed by indirect membrane immunofluorescence (IF). Here we show that S. mansoni schistosomula emerging from lung pieces under 5% CO2 (pH < or = 7.3) readily bind RA vaccine serum antibodies, provided they have been incubated for 12 h at pH 7.5-7.8 in foetal calf serum-free RPMI medium, and fixed with diluted HCHO. Ex vivo larvae exposed during incubation to GW4869, a specific inhibitor of tegument-bound, neutral sphingomyelinase (nSMase) displayed significantly diminished binding of RA vaccine serum antibodies, thus suggesting that nSMase activity at pH > or = 7.5 leads to exposure of lung-stage larvae surface membrane antigens to specific antibody detection. More importantly, ex vivo larvae readily bound antibodies directed to dipeptidic multiple antigen peptide constructs, based on S. mansoni-specific sequences in S. mansoni glyceraldehyde 3-phosphate dehydrogenase (SG3PDH). Lung-stage schistosomula IF reactivity was diminished following antiserum absorption with recombinant SG3PDH. The data together indicate that intact ex vivo, as well as, 5-day-old in vitro-grown larvae express SG3PDH on their surface membrane. The findings are discussed in relation to the importance of surface membrane proteins as candidate vaccine antigens.
authors.affiliation: Zoology Department, Faculty of Science, Cairo University, Cairo 12613, Egypt.
authors.forename: Hatem
authors.initials: H
authors.lastname: Tallima
authors.forename: Rashika
authors.initials: R
authors.lastname: El Ridi
mesh_terms: D000818:Animals; D000947:Antigens, Helminth / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology*; D006224:Cricetinae; D019084:Fluorescent Antibody Technique, Indirect; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+) / Q000276:immunology* / Q000378:metabolism*; D008168:Lung / Q000469:parasitology; D008297:Male; D008647:Mesocricetus; D051379:Mice; D008807:Mice, Inbred BALB C; D012550:Schistosoma mansoni / Q000201:enzymology*; D012555:Schistosomiasis mansoni / Q000276:immunology / Q000469:parasitology
chemical_list: D000947:Antigens, Helminth; D000954:Antigens, Surface; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+)