Factors affecting the detection of cytomegalovirus in urine by sandwich enzyme immunoassays.

Some factors influencing the detection of human cytomegalovirus (HCMV) in urine were investigated employing 2 enzyme-linked immunosorbent assays (ELISAs); one utilised anti-CMV DNA polymerase while the other anti-CMV mouse monoclonals as the detecting antibodies. The use of anti-CMV DNA polymerase was found to be superior in detecting HCMV in both urine and tissue culture fluids than anti-CMV monoclonals. Furthermore, alkaline phosphatase conjugates produced much lower background than did peroxidase conjugates. In reconstruction experiments, the extremes of pH in the urine clearly had an adverse effect on the detection rate of extracellular virus. pH correction of urines to neutrality improved the detection rate considerably. On the other hand, pH correction had little effect on the detection rate of intracellular HCMV in urine, although it was improved when specimens were subjected to repeated cycles of freeze-thawing, ultrasonication, and storage at 4 degrees C. It was concluded that, in addition to the factors investigated which all appear to affect virus detection rate, there may well be additional factors that interfere with CMV detection in the urine by ELISA particularly with intracellular virus.