Comparison of three methods for detecting antibody to cytomegalovirus

To determine the availability of cytomegalic inclusion virus (CMV) antibody-negative blood among our local donor population, 1384 consecutive group O donors were tested for CMV antibody by the indirect hemagglutination assay (IHA); 51 percent (711) were seronegative (titer less than 8). The highest percentage of seronegative findings (60%) was among donors 18 to 35 years old. This age group represented 57 percent of the donors. IHA, enzyme immunoassay (EIA), and passive latex agglutination (PLA) methods were compared on 491 donor samples. The reference method was the anticomplement immunofluorescence test. Sensitivities were: IHA, 89 percent; EIA, 93 percent; and PLA, 90 percent. Specificities were: IHA, 90 percent; EIA, 95 percent; and PLA, 100 percent. All but two of the false-negative samples contained antibody at low titer (less than or equal to 10), which is of doubtful significance relative to transfusion-transmitted CMV infections. All three methods were suitable for screening blood donors. The PLA was easy to perform and had a short processing time that would allow rapid assay of fresh (less than 7 days old) untested blood at the time of selection for transfusion. Thus, both the amount of pretested blood kept in stock and the cost of obtaining each CMV-seronegative unit could be reduced.