Prokaryotic Expression ofa VP1Polypeptide Antigen forDiagnosis bya HumanParvovirus B19Antibody EnzymeImmunoassay

Toproduce parvovirus B19antigen fordiagnostic purposes,partially overlapping segments covering the genesencoding theviral structural proteins VP1andVP2werecloned into expression vectors. Theconstructs were induced inEscherichia coli, resulting intheexpression of,-galactosidase fusion proteins. Inimmunoblotting experiments with serafrompatients witherythema infectiosum, immunoglobulin G (IgG) andIgM antibodies boundtoa single polypeptide of235aminoacids attheN terminus ofVP1.TheDNA fragment encoding this polypeptide wasamplified bythepolymerase chain reaction andcloned into anexpression vector. Theviral capsid antigen expressed inE.coli was purified bypreparative agarosegelelectrophoresis andused inIgGandIgMsolid-phase enzymeimmunoassays. Comparison withreference y-and,L-capture radioimmunoassaysusingwhole virus antigen showed that these antibody tests aresuitable fortheserodiagnosis ofhuman infections caused byparvovirus B19.