Immunization with recombinant leucine aminopeptidase showed protection against Fasciola gigantica in mice.

Leucine aminopeptidase (LAP) is expressed in all stages of Fasciola gigantica and, hence, is considered as a potential vaccine candidate. In this study, we have tested a vaccine potential of LAP and the types of immune responses it elicited in vaccinated mice. Recombinant F. gigantica leucine aminopeptidase (rFgLAP) was expressed in Escherichia coli, BL21 (DE3). The imprinting control region mice subcutaneously immunized with 50 μg of rFgLAP combined with Freund's adjuvant (n = 10) exhibited a significant reduction in worm recoveries when compared with non-immunized and Freund's adjuvant controls at 60.8 and 64.3%, respectively, and both T helper (Th)1 and Th2 humoral immune responses were elicited in the hosts as reflected by the levels of IgG1 and IgG2a, with Th2 predominating. The levels of IgG1- and IgG2a-specific antibodies to rFgLAP were inversely and significantly correlated with the numbers of worm recoveries. The rFgLAP-vaccinated mice showed significantly reduced levels of serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transaminase and liver damage. These indicated that rFgLAP has a potential as a vaccine candidate against F. gigantica, whose efficacy will be studied further in economic animals including cattle, sheep, and goat.