Expression of the human parvovirus B19 protein fused to protein A in Escherichia coli: recognition by IgM and IgG antibodies in human sera.

A 1.4 kb fragment (nucleotides 2430 to 3901) encoding portions of the human parvovirus B19 structural proteins was inserted into the pRIT2 plasmid expression vector containing the gene encoding staphylococcal Protein A under the control of the phage lambda promoter PR. The fusion protein was used to raise antibodies in rabbits. The sera were shown by immune electron microscopy to agglutinate B19 particles and were also shown to recognize the VP2 B19 capsid protein, by Western blot analysis. The B19 antigenicity of the fusion protein was confirmed by immunoblot and enzyme immunoassay with IgG and IgM anti-B19-positive reference human sera.