Fasciola hepatica: Humoral and cytokine responses to a member of the saposin-like protein family following delivery as a DNA vaccine in mice

• Published in: Experimental parasitology 2005-08, Vol.110 (4), p.374-383
• Main Authors: Espino, Ana M., Osuna, Antonio, Gil, Ramón, Hillyer, George V.
• Format: Article
• Language: English
• Subjects: Animals; Antibodies, Helminth - biosynthesis; antibody formation; antigens; Antigens, Helminth - administration & dosage; Antigens, Helminth - genetics; Antigens, Helminth - immunology; Biological and medical sciences; cathepsin L; CatL; CMV; Con A; Concanavalin A; Cytokines - biosynthesis; cytomegalovirus; DBB; denaturing binding buffer; deoxyribonucleic acid; DNA; DNA vaccination; E. coli; EDTA; ELISA; Enzyme-Linked Immunosorbent Assay; Escherichia coli; ethylenediaminotetracetic acid; Fasciola hepatica; Fasciola hepatica - genetics; Fasciola hepatica - immunology; Fasciola hepatica saposin-like protein; Fasciola hepatica saposin-like protein family; fascioliasis; Fascioliasis - immunology; Fascioliasis - prevention & control; Female; FhSAP-2; Fundamental and applied biological sciences. Psychology; Gene Expression; glutathione S-transferase; GST; high performance; Humoral and cellular response; IFA; IFNγ; IL-10; immune response; immunofluorescence assay; Immunoglobulin E - biosynthesis; Immunoglobulin G - biosynthesis; immunoglobulins; interferons; interleukin 10; intramuscular; Life cycle. Host-agent relationship. Pathogenesis; Luria broth; major histocompatibility complex; MHC; Mice; Mice, Inbred BALB C; natural killer; paramethylsulfonilfluoride; PBS; PCR; phosphate-buffered saline; PMSF; polymerase chain reaction; Protozoa; recombinant proteins; Saposins - administration & dosage; Saposins - genetics; Saposins - immunology; SDS; sodium dodecyl sulfate; Spleen - cytology; Spleen - immunology; T-helper cell response type-1; T-helper cell response type-2; Th1; Th2; tissue plasminogen activator; TPA; Trematode; vaccination; vaccine development; Vaccines, DNA - administration & dosage; Vaccines, DNA - immunology; γ interferon
• ISSN: 0014-4894; 1090-2449
• DOI: 10.1016/j.exppara.2005.03.029

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 IFNγ 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 IFNγ 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.