Production of measles nucleoprotein in different expression systems and its use as a diagnostic reagent.

Measles nucleoprotein has been successfully expressed in three different hosts, bacterial (Escherichia coli BL21 DE3), insect (Spodoptera frugiperda; Sf9) and mammalian (primary human fibroblasts) cells, each producing an antigenic protein of M(r) 60 kDa. The nucleoprotein produced in all three hosts was used in an ELISA for the detection of antibodies to measles virus in a cohort of haemagglutinin-positive or -negative human sera. Data produced from baculovirus and adenovirus-based antigens indicated that there was good correlation between the ELISA results and previous haemagglutination inhibition test data, and there was little background interference by cellular proteins or the development of false positive or negative results. The assay was rapid as it could be carried out in under 4 h, sensitive as the sera could be diluted by at least 1000-fold, and versatile as both IgG and IgM could be detected and differentiated.