title: Protective immune responses against Schistosoma mansoni infection by immunization with functionally active gut-derived cysteine peptidases alone and in combination with glyceraldehyde 3-phosphate dehydrogenase.
abstract: Schistosomiasis, a severe disease caused by parasites of the genus Schistosoma, is prevalent in 74 countries, affecting more than 250 million people, particularly children. We have previously shown that the Schistosoma mansoni gut-derived cysteine peptidase, cathepsin B1 (SmCB1), administered without adjuvant, elicits protection (>60%) against challenge infection of S. mansoni or S. haematobium in outbred, CD-1 mice. Here we compare the immunogenicity and protective potential of another gut-derived cysteine peptidase, S. mansoni cathepsin L3 (SmCL3), alone, and in combination with SmCB1. We also examined whether protective responses could be boosted by including a third non-peptidase schistosome secreted molecule, glyceraldehyde 3-phosphate dehydrogenase (SG3PDH), with the two peptidases.
  
  
  
  While adjuvant-free SmCB1 and SmCL3 induced type 2 polarized responses in CD-1 outbred mice those elicited by SmCL3 were far weaker than those induced by SmCB1. Nevertheless, both cysteine peptidases evoked highly significant (P < 0.005) reduction in challenge worm burden (54-65%) as well as worm egg counts and viability. A combination of SmCL3 and SmCB1 did not induce significantly stronger immune responses or higher protection than that achieved using each peptidase alone. However, when the two peptidases were combined with SG3PDH the levels of protection against challenge S. mansoni infection reached 70-76% and were accompanied by highly significant (P < 0.005) decreases in worm egg counts and viability. Similarly, high levels of protection were achieved in hamsters immunized with the cysteine peptidase/SG3PDH-based vaccine.
  
  
  
  Gut-derived cysteine peptidases are highly protective against schistosome challenge infection when administered subcutaneously without adjuvant to outbred CD-1 mice and hamsters, and can also act to enhance the efficacy of other schistosome antigens, such as SG3PDH. This cysteine peptidase-based vaccine should now be advanced to experiments in non-human primates and, if shown promise, progressed to Phase 1 safety trials in humans.
authors.affiliation: Zoology Department, Faculty of Science, Cairo University, Giza, Egypt.|Department of Chemistry, School of Science and Engineering, American University in Cairo, New Cairo, Cairo, Egypt.
authors.forename: Hatem
authors.initials: H
authors.lastname: Tallima
authors.affiliation: School of Biological Sciences, Medical Biology Centre, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Dvořák
authors.affiliation: Zoology Department, Faculty of Science, Cairo University, Giza, Egypt.
authors.forename: Sahira
authors.initials: S
authors.lastname: Kareem
authors.affiliation: Zoology Department, Faculty of Science, Ein Shams University, Cairo, Egypt.
authors.forename: Marwa
authors.initials: M
authors.lastname: Abou El Dahab
authors.affiliation: Chemistry Department, Faculty of Science, Cairo University, Giza, Egypt.
authors.forename: Nada
authors.initials: N
authors.lastname: Abdel Aziz
authors.affiliation: School of Biological Sciences, Medical Biology Centre, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: John Pius
authors.identifier: 0000-0003-3829-9186
authors.initials: JP
authors.lastname: Dalton
authors.affiliation: Zoology Department, Faculty of Science, Cairo University, Giza, Egypt.
authors.forename: Rashika
authors.initials: R
authors.lastname: El Ridi
mesh_terms: D000818:Animals; D000947:Antigens, Helminth / Q000008:administration & dosage / Q000276:immunology*; D002401:Cathepsin B / Q000008:administration & dosage / Q000276:immunology*; D056668:Cathepsin L / Q000008:administration & dosage / Q000276:immunology*; D006224:Cricetinae; D004195:Disease Models, Animal; D041981:Gastrointestinal Tract / Q000201:enzymology*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000008:administration & dosage / Q000276:immunology*; D007279:Injections, Subcutaneous; D051379:Mice; D059208:Parasite Load; D012550:Schistosoma mansoni / Q000276:immunology*; D012555:Schistosomiasis mansoni / Q000276:immunology / Q000517:prevention & control*; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D000947:Antigens, Helminth; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D002401:Cathepsin B; D056668:Cathepsin L