[en] Nuclear techniques such as radioimmune precipitation, radioimmunoassay, DNA cloning and amino acid sequencing have led to a greater understanding of protein structure and function, antigenic variation and the immune response to infection. Knowledge gained from the use of this technology has led to the development of improved diagnostic assays. Although radioimmunoassay has been used for animal disease diagnosis for many years, more recently it has been replaced by the enzyme linked immunosorbent assay (ELISA). The ELISA offers advantages in speed of reading and longer reagent shelf life and obviates the use of radiochemicals. This is particularly important in developing countries, which may have no facilities for storage, handling and disposal of radioactive materials. In the case of rinderpest diagnosis, taken as an example, the virus neutralization test was replaced by a simple indirect ELISA for seromonitoring throughout the Pan-African Rinderpest Campaign. In the near future, this will be replaced by a competitive ELISA using a rinderpest specific monoclonal antibody, which will offer significant advantages in sensitivity and specificity. In the future it may be possible to replace the rinderpest antigen with vector expressed proteins or synthetic polypeptides. More recent developments such as the 'amplified' ELISA and the use of fluorogenic and bioluminescent substrates may further improve disease diagnosis. The knowledge gained from the use of modern technology is essential to the development of improved diagnostic assays which in turn will lead to improved disease diagnosis and control. (author). 9 refs