A cell penetrating peptide in the delivery of plasmid DNA encoding Fasciola gigantica fatty acid binding protein in mice

Fatty acid binding protein of Fasciola gigantica was evaluated for evoking immune responses in mice in a DNA immunization study using a cell penetrating peptide as a delivery vehicle. Three cell penetrating peptides named R-19, R-22 and R-25, derived from the infectious bursal disease virus, were synthesized and evaluated for their potential in the delivery of a plasmid DNA encoding Fasciola gigantica fatty acid binding protein in mouse muscle and peritoneal cells. Out of the three peptides, R-22 when complexed with the plasmid DNA, evoked a humoral immune response by eliciting IgG antibodies. The mice responding to the immunization by this peptide-DNA complex evoked IgG1, IgG2a and IgG2b isotype response, indicating a mixed Th1/Th2 response. Four mice (4/10) responded to the immunization by this peptide-DNA complex in each of the intramuscular and intraperitoneal immunized groups. The other two peptides did not evoke any antibody response. The mice showing the elicitation of humoral response were assayed for cytokine production of IFN, TNF, IL-2, IL-4 and IL-5. Out of the five cytokines assayed, mice showed the production of TNF on in vitro stimulation of the splenocytes by recombinant fatty acid binding protein. This pilot study shows a potential for R-22 peptide in the DNA delivery in DNA vaccination strategy. However, further studies are needed on this peptide for the enhanced delivery of the DNA to the mouse muscle and peritoneal cells.