Use of rubella virus E1 fusion proteins for detection of rubella virus antibodies

Two glutathione S-transferase fusion proteins containing 44 (p1503) and 75 (p1509) amino acid residues of the rubella virus E1 glycoprotein were expressed in Escherichia coli with the aim of producing a recombinant rubella virus antigen for use in serological assays. p1503 contained three neutralizing and hemagglutinating epitopes (G. M. Terry, L. M. Ho-Terry, P. Londesborough, and K. R. Rees, Arch. Virol. 98:189-197, 1988); p1509 contained the putative neutralization domain described by Mitchell et al. (L. A. Mitchell, T. Zhang, M. Ho, D. Decarie, A. Tingle, M. Zrein, and M. Lacroix, J. Clin. Microbiol. 30:1841-1847, 1992) in addition to the three epitopes present in p1503. Both fusion proteins were soluble and affinity purified on glutathione-Sepharose 4B. In Western blots (immunoblots), p1503 and p1509 reacted with human sera containing rubella virus-specific immunoglobulin G. When used as antigens in indirect enzyme immunoassays to detect rubella virus-specific immunoglobulin G, p1503 correctly identified the rubella virus antibody status of 43 (76.8%) and p1509 correctly identified that of 48 (85.7%) of 56 serum samples received for routine rubella virus antibody screening. The results obtained with p1509 compare well with those obtained with a latex agglutination assay.