Isotype-specific serum IgG responses of llamas (Lama glama) to experimental liver fluke infection

The humoral immune system of South American camelids is unusual in that a large component of the IgG comprises heavy chains only. The objective of this study was to assess the contribution of these and conventional four chain IgG antibodies to the immune response of llamas in the course of primary infections with the liver fluke Fasciola hepatica. Isotypes of IgG were isolated by affinity chromatography and the production of various isotypes determined by ELISA. Both conventional and heavy-chain only isotypes of F. hepatica-specific IgG were detected in the course of the infection. The conventional four-chain antibody, IgG1, predominated but a marked increase was also detected in the heavy-chain only isotype IgG3. IgG2, another heavy-chain only isotype, was a minor component of the fluke specific response.