Development of a dot blot neutralizing assay for HHV-6 and HHV-7 using specific monoclonal antibodies

To elucidate further immune responses to human herpesviruses 6 and 7 (HHV-6 and -7), a neutralizing antibody assay was established for these viruses using a dot blot method. Three monoclonal antibodies against HHV-6 and 12 monoclonal antibodies against HHV-7 were developed and characterized by radio-immunoprecipitation. One monoclonal antibody which recognizes the 135 kDa late polypeptide of HHV-6 and several which recognize the 125 kDa late polypeptide of HHV-7 were selected to monitor virus growth by a dot blot antigen-detection method. The dot blot method was then used for the assay of HHV-6 and -7 neutralizing antibodies in human serum samples. The neutralization endpoints determined by the dot blot were comparable to those determined by immunofluorescence (IF). The neutralizing antibody titers appeared to correlate with the antibody titers determined by the indirect IF antibody test. The dot blot neutralization assay is easy to perform, is highly reproducible and objective when compared with the conventional methods based on cytopathology or IF for determining neutralization endpoints.