Antibody responses to Lucilia cuprina in sheep selected for resistance or susceptibility to L. cuprina.

Sheep bred for resistance (R) or susceptibility (S) to fleece rot and myiasis (blowfly strike) have been shown to differ in inflammatory response to intradermal administration of blowfly (Lucilia cuprina) antigens and artificial challenge. The current paper describes analysis of antibody responses to L. cuprina antigens in the R and S animals. Serum antibody titres and specificities to larval antigens were examined and the specificity of wound exudate antibodies was also investigated in animals artificially challenged with L. cuprina. Titres of L. cuprina specific serum IgA, IgM, IgG2 and IgG1 were measured by ELISA, while specificities were examined on two-dimensional immunoblots of larval homogenates. Exposure to L. cuprina stimulated the production of specific antibody in both R and S animals, however antibody titres did not differ between the R and S animals. There was large variation in antibody specificity between individual animals and some L. cuprina proteins appear to be more frequently recognized by sera from either resistant or susceptible animals, however the recognition of a specific protein could not be solely attributed to the resistance status of the animal. It appears that resistance in these animals may be independent of serum antibody and is likely to be an innate response. Despite high levels of IgG in wound exudates, this antibody recognized few antigens in comparison with serum from the same animal, suggesting that exudate contains little functional antibody in comparison to serum.