Fatty acids bound to Fasciola hepatica 12 kDa fatty acid-binding protein, a candidate vaccine, differ from fatty acids in extracts of adult flukes.

The FA composition of Fasciola hepatica 12 kDA purified native FA-binding protein (nFh12), a candidate vaccine against fascioliasis, is described. The FA chain lengths ranged between 12 and 24 carbons. The principal FA were 16:0, 18:1n-9, 18:0, 20:4n-6, and 20:1n-9. The acids 16:0, 18:1n-9, and 18:0 comprised over half the FA that were bound to the whole FA-binding protein. Small amounts (1.0-2.8%) of iso-anteiso methyl-branched FA also were characterized. Forty-one different FA were identified in extracts of the adult flukes, with the three most abundant FA also being 16:0, 18:1n-9, and 18:0. A similar proportion of saturated vs. unsaturated FA was observed between the whole extract from F. hepatica and the nFh12 protein. However, the n-3/n-6 ratio of PUFA was significantly different, being 1.2 in the whole extract vs. 9.6 in the nFh12 protein complex. The nFh12 protein binds more n-5, n-6, and n-7 PUFA and less n-3 and n-9 PUFA than the whole extract. In addition, cholesterol (56%), sitosterol (36%), and fucosterol (8%) also were bound to the nFh12 protein complex.