A comparison of inflammatory exudates released from myiasis wounds on sheep bred for resistance or susceptibility to Lucilia cuprina.

Sheep bred for resistance (R) or susceptibility (S) to fleece rot and myiasis (blowfly strike) were experimentally infected with L. cuprina larvae. Exudates released from the wound site were collected during the infection at 6, 12, 18 and 24 h. The exudates were separated using two-dimensional gel electrophoresis, and proteins were silver stained and identified by immunoblotting with specific antibody and by their isoelectric points and molecular weights. Comparisons of exudate composition were made over time and between R and S sheep. Between 6 and 12 h post larval implantation the exudate was rich in IgG and fibrinogen, which is before extensive tissue damage and suggests that the exudate is not simply tissue haemorrhage but the result of an inflammatory response by the sheep to L. cuprina. The exudate grew in complexity between 12 and 18 h and contained a maximum of 74 distinct peptide spots by 24 h. Exudate from wounds on resistant sheep contained many more peptides in the first 12 h of infection, suggesting a more rapid inflammatory response. The source of proteins from the exudate remains speculative; it appears to be composed of many acute-phase proteins, large amounts of immunoglobulin G and proportionally low levels of serum albumin. Exudate composition is likely to be influenced by the local synthesis of acute-phase proteins and perhaps immunoglobulins, selective transport to the infection site and also enzymic degradation by L. cuprina larval enzymes. The more rapid exudation of acute-phase and serum proteins at infection sites on R sheep may allow the inhibition of the establishment of fleece rot bacteria or L. cuprina larvae under natural challenge.