Successful DNA immunisation of rats against fasciolosis.

The liver fluke Fasciola hepatica contributes to great economic and health losses in the cattle industry in many countries, including Poland. Unfortunately, no vaccine against fasciolosis is commercially available. We have designed a DNA vaccine and tested it in rats. Groups of male or female rats received one intramuscular injection of 50 microg of a pcDNA 3.1 vector carrying cDNA encoding for a cysteine proteinase of F. hepatica. The plasmid was diluted in saline containing 0.05% bupivacaine. Control rats were injected with empty plasmid or not injected at all. All rats were challenged with 45 metacercariae of the fluke on day 28 of the experiment. Seven weeks after the challenge infection fluke burdens were evaluated in vaccinated and control rats. Male rats vaccinated with cysteine proteinase cDNA revealed 100% protection against F. hepatica infection. Females immunised in the same way exhibited the reduction of fluke burden by 74%.