Comparison of monoclonal and polyclonal antibody for confirmation of cytomegalovirus isolates by fluorescent staining.

A fluorescein isothiocyanate-labeled monoclonal cytomegalovirus antibody reagent incorporating Evans blue (Syva/Genetic Systems, Palo Alto, Calif.) was compared to a fluorescein isothiocyanate-labeled polyclonal antibody (Dynatech Diagnostics, Inc., South Windham, Maine) for identification of cytomegalovirus in tissue culture. A total of 191 cultures, 86 positive and 105 negative for cytomegalovirus by cytopathic effect in WI38 cells, were stained in parallel and examined by fluorescent microscopy. No false-negative results were noted with either reagent; however, the polyclonal antibody-stained slides required the use of a separate counterstain to decrease nonspecific fluorescence. The polyclonal reagent gave a false-positive reaction with one varicella-zoster virus isolate and four simian cytomegalovirus isolates. No false-positive results were noted with the monoclonal reagent.