Detection of cytomegalovirus in urine samples by an enzyme-linked immunosorbent assay using a monoclonal antibody against the viral 150- kilodalton protein

McKeating et al. (J. A. McKeating, P. D. Griffiths, and J. E. Grundy, J. Gen. Virol. 68:785-792, 1987; J. A. Mckeating, J. E. Grundy, Z. Varghese, and P. D. Griffiths, J. Med. Virol. 18:341-348, 1986; J. A. McKeating, S. Stagno, P. R. Stirk, and P. D. Griffiths, J. Med. Virol. 16:367-373, 1985) reported previously that β₂ microglobulin inhibits the detection of human cytomegalovirus (CMV) in urine specimens by an enzyme-linked immunosorbent assay (ELISA) with a monoclonal antibody against the glycoprotein of CMV. They postulated that β₂ microglobulin binds to the viral glycoproteins and masks the antigenic determinants. We developed here an ELISA method for the detection of CMV in urine by using a monoclonal antibody against the viral 150-kDa protein to capture the viral antigen. This assay detected CMV both in culture medium and in urine specifically at concentrations higher than 10³ PFU/ml and quantitatively at concentrations higher than 10⁴ PFU/ml. The sensitivity of the ELISA increased about 10-fold when peroxidase-labeled F(ab')₂ from goat anti-human immunoglobulin G was used as a secondary detecting antibody in combination with concentration of the virus in urine samples by ultracentrifugation. The inhibition of ELISA by β₂ microglobulin was not observed in this ELISA system. When 56 urine specimens from renal transplant recipients were examined for CMV antigens, the ELISA system had a sensitivity of 78% and a specificity of 97%. The positive and negative predictive values of the assay were 95 and 86%, respectively. Furthermore, CMV antigens in urine were quantitated by the assay during the course of typical CMV disease of a renal transplant recipient. These results suggest strongly that the measurement of CMV antigens in urine by our rapid and quantitative ELISA system provides very useful data for the monitoring of CMV infections in renal transplant recipients and making decisions about therapy.