Potential of recombinant 2-Cys peroxiredoxin protein as a vaccine for Fasciola gigantica infection.

Helminth 2-cys peroxiredoxin (Prx) is a major antioxidant enzyme that protects parasites against hydrogen peroxide-generating oxidative stress from the hosts' immune responses. This enzyme has been found in all stages of the tropical liver fluke, Fasciola gigantica. To investigate the potential of the recombinant F. gigantica Prx-2 (rFgPrx-2) as a vaccine candidate, vaccine trials in mice were carried out. In this study, the ICR mice were immunized with rFgPrx-2 combined with Freund's adjuvant and infected with F. gigantica metacercariae. The vaccine efficacy was estimated by quantitate fluke recovery, antibody levels and liver function. The protection by rFgPrx-2 against F. gigantica infection was achieved at 43-46% compared with adjuvant-infected and non-immunized-infected control groups, respectively. The vaccine elicited both Th1 and Th2 humoral immune responses with predominance of Th2 as indicated by the higher level of IgG1 in sera of immunized mice. However, the levels of liver damage markers, serum glutamate oxalic transaminase (SGOT) and serum glutamic pyruvate transaminase (SGPT) in rFgPrx-2 immunized group did not show significant difference in comparison with the controls. This study suggested that rFgPrx-2 may have a potential as a vaccine against tropical fasciolosis.