Appendix 28
FAO Collaborative Study Phase XVII: Standardisation of FMD Antibody Detection D J Paton, R M Armstrong, L S Turner, P A Hamblin, M Corteyn, D Gibson, J Anderson Institute for Animal Health, Ash Road, Pirbright, Woking Surrey GU24 0NF
Introduction The aims of the current study were agreed at the FAO EU FMD meeting in Borovets, 2000. The previously agreed reference sera to O Manisa, A22 and C Noville were to be adopted by O.I.E. as official standards. New reference sera were to be prepared against O SKR, A Iran 96 and Asia 1 Shamir. These should be distributed for evaluation, along with a panel of coded proficiency test sera. New primary sera were prepared at the start of 2001, but the FMD epidemic severely delayed subsequent progress. During 2002, the candidate reference sera were distributed and this report is mainly concerned with their evaluation. No proficiency testing with a panel of coded sera was performed. Materials and Methods Candidate reference sera for each of the FMD strains O SKR, A Iran 96 and Asia 1 Shamir were derived by diluting strong positive original sera in a standard, pooled negative serum (Table 1). Strong positive original sera were obtained from cattle after either intradermolingual inoculation (O SKR) or vaccination, including a 21 day boost (A Iran 96 and Asia 1 Shamir). Participants (Table 2) were requested to examine the sera by both ELISA and virus neutralisation test (VNT). In the case of ELISA, participants were asked to use both the liquid phase blocking ELISA (LPBE) and the solid phase competition ELISA (SPCE) as well as other available tests, including those for non-structural (NS) antibodies. All laboratories received a protocol for a version of the SPCE modified from that of Mackay et al. (2001), along with the necessary reagents for a serotype O version of the test. Results Results were available from all but one of the laboratories that had been sent samples and these are summarized in Tables 3-6. For the standard tests, the cut-offs used at Pirbright have been applied for interpretation of the results, although it is appreciated that other interpretations may be in use. Some results are not tabulated, since they were not directly comparable due to differences in the way the tests were performed or in which the results were expressed. The negative serum was found negative in all tests, in all labs.
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