Document details for 'Development of a serodiagnostic test for sheep scab using recombinant protein, Pso o 2'

Authors Nunn, F.G., Burgess, S.T.G., Innocent, G.T., Nisbet, A.J., Bates, P. and Huntley, J.F.
Publication details Molecular and Cellular Probes 25(5-6), 212-218.
Keywords Diagnostic test, sheep scab, recombinant protein
Abstract Sheep scab, caused by the non-burrowing mite Psoroptes ovis, is endemic in the UK, causing significant losses to the industry as well as being a major animal welfare concern. Early stages and low levels of infestation are often not obvious, or can be mis-diagnosed as louse or other ectoparasitic infestations, so a diagnostic test capable of detecting early disease and latent infestations is highly desirable in disease control strategies. This paper describes the design and validation of a pathogen-specific ELISA incorporating a recombinant version of the P. ovis mite antigen Pso o 2 to test for serum antibodies in infested sheep. Using a Pso o 2-based ELISA to detect P. ovis-specific antibodies, significant differences were demonstrated between data obtained from P. ovis-negative sheep and P. ovis-positive sheep in experimental and field samples. The test demonstrated high specificity with no significant difference between optical density (OD) values of P. ovis-negative sheep and those that were P. ovis-negative but infected with other parasites including gastrointestinal nematodes (GIN), chewing lice and ticks. A receiver operating characteristic (ROC) curve analysis was generated from nearly 500 clinically negative and positive samples with the area under the curve being 0.97. An optimal OD450 cut-off of 0.06 absorbance units gave a test sensitivity of 0.93 and specificity of 0.90. To confirm that the original ROC data set was representative of the population an additional set of samples was tested and these were not significantly different from the values anticipated using the sensitivity and specificity stated above. The Pso o 2-based ELISA was applicable for detecting antibodies to P. ovis during early experimental infestation prior to disease patency, indicating a role in detecting sub-clinical infection. The test is therefore robust, sensitive and specific and would be useful in future control or eradication programs.
Last updated 2013-09-26
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