The construction of a cDNA expression library for the sheep scab mite Psoroptes ovis

The need for alternative control strategies for sheep scab is critical. One approach is to develop vaccines based on 'concealed' antigens derived from Psoroptes ovis. This strategy requires the identification and characterisa tion of potential target antigens, which has been hampered by the problem o f limited biological material for isolation of protein antigens. To aid the discovery of P. ovis antigens and to provide a resource for generating rec ombinant protein, we constructed a P. ovis cDNA expression library, using t otal RNA isolated from 250 mg of mixed-stage P. ovis and the Clontech SMART (TM) cDNA synthesis kit. The presence of P. ovis-specific sequences was con firmed using PCR amplification and sequencing of actin. The sequences of cD NA inserts from six random clones included one with high homology to the De rmatophagoides pteronyssinus (house dust mite) antigen p Dp15. This is a gl utathione S-transferase known to be an important house dust mite antigen. W e conclude that this library will be a useful tool for the identification o f potential target antigens for the immunological control of P. ovis and to further our understanding of the pathology of sheep scab. (C)1999 Elsevier Science B.V. All rights reserved.