Appendix 33
A comparison of two 3ABC ELISA’s in an African cattle population with endemic multiple serotype Foot-and-Mouth disease B.M.deC. Bronsvoort1, K.J. Sørensen5, J. Anderson3, A. Corteyn3, V.N. Tanya2, R.P.Kitching4, K.L. Morgan1 1
University of Liverpool, Dept. Veterinary Clinical Sciences and Animal Husbandry, Leahurst, Neston, Wirral, CH64 7TE, UK. 2 Institute of Agricultural Research for Development, Regional Centre of Wakwa, B.P. 65, Ngaoundere, Cameroon. 3 Institute of Animal Health, Ash Road, Pirbright, Woking, Surrey, GU24 0NF, UK. 4 National Centre for Foreign Animal Disease Canadian Food Inspection Agency Winnipeg, Manitoba, Canada. 5 Danish Veterinary Institute, Virology Department, Lindholm, DK4771 Kalvehave, Denmark.
Keywords: 3ABC, CHEKIT, competitive ELISA, ROC Abstract The development of a foot-and-mouth disease virus (FMDV) serological test which is quick and easy to use, which can identify all 7 serotypes and which can differentiate vaccinated from convalescing or potential carriers would be a major advance in the epidemiological tool kit for FMDV. The polyprotein 3ABC has recently been proposed as such an antigen and a number of diagnostic tests are being developed. This paper compares the performance of the 3ABC FMD CHEKIT bov-ov ELISA (Bommeli) and a competitive 3ABC ELISA developed in Denmark, in an African cattle population in an endemic FMDV region of Cameroon with multiple serotypes. The test parameters (sensitivity, specificity and predictive value) were examined over a range of test cut-off’s. The results indicate that both tests lack sensitivity though the CHEKIT-ELISA is particularly low at the recommended cut-off. Their performances at different cut-off’s and how they might perform at the herd-level are discussed. Introduction The non-structural proteins (NSP) of foot-and-mouth disease virus (FMDV) have received considerable attention in recent years with the search for improved serological tests for FMDV 1-5. The virus neutralisation test (VNT) 6 and liquid phase blocking ELISA (LPBE) 7-9 are currently the recommended tests by the OIE. However, these tests require each serotype to be tested separately, are time consuming to perform, require virus containment facilities and cannot differentiate vaccinated from convalescing animals. The development of a single, quick to use test that covered all 7 serotypes as well as differentiating vaccinated from convalescing animals would be a major advance in the epidemiological tool kit for FMDV. The NSP’s are only expressed in animals with replicating virus and therefore only animals that have been infected with live virus should develop antibodies to these 272
