Immune response in alpacas against Fasciola hepatica cysteine proteinases Fas1 and Fas2*

A characterization of the humoral immune response of alpacas to Fasciola hepatica Fas1 and Fas2 antigens cysteine proteinases was performed over the course of 6 months of experimental infection. Six adult alpacas aged 1 to 2 years old received a single dose of 200 F. hepatica metacercariae, 2 non–infected alpacas were kept as control group. Peripheral eosinophilia in infected animals was greatly enhanced 6 weeks PI and later. A single peak of alanine aminotransferase (SGPT) was observed 4 week PI and aspartate aminotransferase (SGOT) elevated 3 weeks PI and later. All infected animals shed eggs 8 week PI and the number of flukes recovered at necropsy averaged 41 ± 4. Circulating IgG Abs against Fas1 and Fas2 were measured by ELISA. Fas2-ELISA detected the infection 10 days PI reaching to highest titer on 7-8 week PI and kept elevated until the end of infection. Fas1-ELISA detected the infection 2 weeks PI and followed the same pattern as Fas2-ELISA. Anti Fas2 IgG Abs were in higher titers and showed stronger avidity than anti Fas1 IgG Abs. In the present study we have established a F. hepatica experimental infection of alpacas that might be employed as a model to search for genes involved in the susceptibility to helminth infection in alpacas.