title: Fasciola hepatica: humoral and cytokine responses to a member of the saposin-like protein family following delivery as a DNA vaccine in mice.
abstract: The humoral and cellular responses to DNA vaccination of BALB/c mice with a novel antigen from the Fasciola hepatica saposin-like protein family (FhSAP-2) have been investigated. Two constructs were produced containing the FhSAP-2 DNA sequence, one intended for extracellular secretion of FhSAP-2 protein, and one expressing FhSAP-2 in the cytoplasm of a transfected cell. The constructs were tested in HEK 293T cells, with the secretory construct producing less detectable FhSAP-2 relative to cytoplasmic construct when observed by fluorescence. The size of expressed protein was confirmed by Western blot of cell lysate, but FhSAP-2 was undetectable in cell supernatants. Both, secretory and cytoplasmic constructs as well as FhSAP-2 recombinant protein were tested in mice. The antibody response elicited in mice vaccinated with the rFhSAP-2 induced high levels of IgG(1), IgG(2), and IgE as well as high levels of IL-10 and IFNgamma indicating a mixed Th1/Th2 response. Vaccination of mice intramuscularly with the cytoplasmic FhSAP-2 construct resulted in a dominant IgG(2a) isotype antibody as well as a dominant IFNgamma cytokine, with significant IgE, IgG(1), and IL-10 responses also present, suggesting a mixed Th1/Th2 profile. Isotype and cytokine profiles elicited by the FhSAP-2 secretory construct were similar to those obtained with the cytoplasmic construct but at levels that were significantly lower. The results demonstrate that FhSAP-2 can be delivered as a DNA vaccine construct and induces a stronger Th1 response than the recombinant protein alone. This could result in an improvement in the immunoprophylactic potential of this candidate vaccine against F. hepatica.
authors.affiliation: Laboratory of Molecular Parasitology and Immunology, Department of Microbiology, University of Puerto Rico, School of Medicine. aespino@rcm.upr.edu
authors.forename: Ana M
authors.initials: AM
authors.lastname: Espino
authors.forename: Antonio
authors.initials: A
authors.lastname: Osuna
authors.forename: Ramón
authors.initials: R
authors.lastname: Gil
authors.forename: George V
authors.initials: GV
authors.lastname: Hillyer
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000096:biosynthesis*; D000947:Antigens, Helminth / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D016207:Cytokines / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay; D005210:Fasciola hepatica / Q000235:genetics / Q000276:immunology*; D005211:Fascioliasis / Q000276:immunology / Q000517:prevention & control; D005260:Female; D015870:Gene Expression; D007073:Immunoglobulin E / Q000096:biosynthesis; D007074:Immunoglobulin G / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D049231:Saposins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D016207:Cytokines; D007074:Immunoglobulin G; D049231:Saposins; D019444:Vaccines, DNA; D007073:Immunoglobulin E