Bluetongue laboratory diagnosis: a ring test to evaluate serological results using a competitive ELISA kit.

The occurrence of bluetongue (BT) in Italy prompted an increase in disease surveillance. Thus a competitive enzyme-linked immunosorbent assay (c-ELISA) to detect immunoglobulins to BT virus (BTV) was developed and distributed amongst 27 laboratories comprising the Italian veterinary diagnostic laboratories network to screen field sera. This ring test enabled comparison of the results and the evaluation of the reproducibility of the method. The c-ELISA developed by the National Reference Centre for Exotic Diseases (c-ELISA-IZSA&M) was compared also against a commercially available c-ELISA. In addition, results obtained by the Centre of Athens Veterinary Institutions are presented.