ICRAD Development of a rapid screening test for on-site diagnostics of caprine arthritis-encephalitis using individual milk samples

The main goal of this CAE-project is to develop a test for early diagnosis of CAE on farm. The test should be simple and rapid and use directly on milk samples from the farm. More than 1000 milk and blood samples from Norwegian Goats have now been sampled. In addition, milk and blood samples from CAE-infected herds in Hungary, Lithuanian and Poland have also been collected. CAE-virus from 5 goats have been isolated and characterized,and 6 viral antigens have been produced. These antigens are now tested in different combinations for optimalization. Thereafter, the optimized test-chip will be produced and further tested and evaluated on the field collected samples (serum and milk) from Norway, Hungary, Lithuanian and Poland. Due to COVID-19 the optimalization of the test has been delayed, but this work is now in progress and the project will most properly be finalized within the scheduled time.

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CAE-RAPID aims to improve individual diagnostics of CAE by providing an easy available tool for reliable exclusion and early detection of the disease. The rapid test for tetection of anitibodies to SRLV in a drop of milk, serum or Whole blood will be intended for use in two basic situations. First, for on-site quick screening of asymptomatic goats which are intended to be purchased or introduced into the herd. Second, for on-site quick screening of goats in which first clinical signs have emerged. The test will be screening diagnostic methods so it will be expected to maximize diagnostic sensitivity and negative predictive value, so that a goat that test negative can be safely introduced into or retained in the herd. Positive results will need verification in the laboratory. To develop a highly reliable, accurate and easy to use in-field test the most prevalent SRLV genotypes and subtypes will be identified in a large scale virological survey carried out in CAE-affected goat herds. The most optimal viral antigen capable of detecting antibodies will be evaluated by developing and comparing Several immunoenzymatic test (WP1). The most optimal antigen will be used to develop the rapid immunochromatographic test (WP2). The CAE_RAPID test will be validated in laboratory (WP3) and field conditions (WP4). in WP3 a large number of SLRV-infected goats and uninfected goats will be included, in order to determine the sennsitivty and specificity of the test on both milk and blood samples. In WP4 the CAE-RAPID test will be used in field conditions to verify the diagnostic performance and reliability in a blinded study.