Molecular characterization, expression and localization of a peroxiredoxin from the sheep scab mite,Psoroptes ovis

Abstract

SUMMARYThe sheep scab mite,Psoroptes ovis, induces an intensely pruritic exudative dermatitis which is responsible for restlessness, loss of appetite and weight loss. Within the first 24 h of infection, there is a rapid inflammatory influx of eosinophils and apoptosis of the keratinocytes at the site of infection. The former cell type is capable of a sustained respiratory burst, toxic products of which may directly damage the mite and also contribute to lesion formation. Analysis of aP. ovisexpressed sequence tag (EST) database identified a number of antioxidant enzyme-encoding sequences, including peroxiredoxin (thioredoxin peroxidase EC 1.11.1.15), all of which may help the mite endure the potentially toxic skin environment. A full length sequence encodingPo-TPx, a protein of 206 amino acids which showed high homology to a peroxiredoxin from the salivary gland of the tickIxodes scapularis, was amplified fromP. oviscDNA. RecombinantPo-TPx was expressed in bacteria and antiserum to this protein was used to localize nativePo-TPx in mite sections. Peroxiredoxin was localized, amongst other sites, to a subpharyngeal region in mite sections. The recombinant protein was recognized by sera from sheep infested with the mite suggesting that it may be secreted or excreted by the mite and interact with the host immune response.