Splenic gene expression profile of mice immunized with an anti-Fasciola hepatica vaccine candidate: insights into the immunological mechanisms leading to protection

Fasciolosis remains an important food-borne tremaode disease causing high morbidity around the world and affecting grazing animals and humans. A deeper understanding concerning the molecular mechanisms by which Fasciola hepatica infection occurs as well as the molecular basis involved in acquiring protection is extremely important in designing and selecting new vaccine candidates. The present study gives a first report of microarray-based technology for describing changes in splenic gene expression profile for mice immunised with a highly effective, protection-inducing,multi-epitope, subunit-based, chemically-synthesised vaccine candidate. Female CD1 mice were immunised with synthetic peptides containing B- and T-cell epitopes as novel vaccine candidates and challenged with Fasciola hepatica metacercariae. Spleen RNA from mice immunised with the highest protection-inducing synthetic peptides was isolated, amplified and labelled using Affymetrix standardised protocols. The Ingenuity Pathway Analysis tool was used to annotate bio-functions and constructing and visualising molecular interaction networks. Immunising mice with a combination of three peptides containing T-cell epitopes induced high protection against experimental challenge according to survival rates and hepatic damage scores. It also induced differential expression of 820 genes; 168 being up-regulated and 652 down-regulated. Functional study revealed changes in pathways related to nitric oxide and reactive oxygen species production, IL-12 signalling and production in macrophages and IL-8 signalling with up-regulation of S100A8, MMP9 and CXCR2 genes. The data obtained in the present study provided us with a more comprehensive overview concerning the possible molecular pathways implied in inducing protection against Fasciola hepatica in a murine model

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