Maturation of IgG avidity to individual rubella virus structural proteins

Background: the structural proteins of rubella virus, the capsid protein C and the envelope glycoproteins E1 and E2 were produced in lepidopteran inse ct cells using baculovirus expression vectors. The C-terminal ends of the c orresponding proteins were fused to a polyhistidine tag for easy and gentle purification by metal ion affinity chromatography. Objectives: to investig ate the maturation of natural and vaccinal IgG avidity against individual a uthentic and recombinant rubella virus (RV) structural proteins. Study desi gn the analysis was carried out using a modified immunoblotting technique w here the purified baculovirus-expressed proteins were compared with authent ic rubella virus proteins. Altogether, 47 well-characterised serum samples from both naturally infected patients and vaccines were studied. Results: a fter natural RV infection, IgG antibodies specific for the E1 protein were predominant not only in terms of levels, but also in terms of rate and magn itude of avidity maturation. The avidity development of the IgG antibodies was much slower in vaccines than in patients after a natural RV infection. Conclusions: together, our results indicate that IgG avidity determination in conjunction with immunoblot analysis is useful in the diagnosis of a RV infection. The recombinant proteins showed similar reactivity patterns in t he immunoblot analyses as compared with the authentic viral structural prot eins, suggesting suitability for serodiagnostics. (C) 2001 Elsevier Science B.V. All rights reserved.