Rapid (24h) neutralization assay for the detection of antibodies to human cytomegalovirus using a monoclonal antibody to an HCMV early nuclear protein

Neutralizing antibodies to human cytomegalovirus (HCMV) may play an important role during the course of an HCMV infection but yet detection with conventional methods remains difficult and time consuming. A new neutralization test has been developed basically corresponding to the known microtitre technique. A monoclonal antibody to an HCMV early nuclear protein is utilized to detect HCMV (AD169) infected fibroblasts by biotin/streptavidin-enhanced immunoperoxidase staining. The test procedure was thereby confined to only 24 h. Evaluation of the new neutralization test (24h-NT) was done in comparison to the conventional method (NT). Preselected serum samples (n = 217), of which n = 169 were HCMV-seropositive in ELISA (reciprocal titre greater than or equal to 40), were tested for neutralizing antibodies (NAbs) to HCMV. ELISA titres were measured by a commercially available kit (Behring, F.R.G.). NAbs could be detected in 107 sera by 24h-NT (reciprocal titre greater than or equal to 5) and in 110 sera determined by NT (reciprocal titre greater than or equal to 5). Those sera were exclusively positive in ELISA. ELISA negative sera (n = 48; reciprocal titre less than 40) yielded no detectable neutralizing titres. This specific and rapid test should facilitate HCMV-NAbs detection for a wide variety of applications including routine virology diagnostics, evaluation of HCMV hyperimmunoglobulins and medical research.