Received on July 12, 2003
Accepted on November 26, 2003

Molecular Diagnostics and Genetics

Detection of Human Polyomaviruses in Urine from Bone Marrow Transplant Patients: Comparison of Electron Microscopy with PCR

¹ Beiersdorf AG, Hamburg, Germany, and Robert Koch Institute, Berlin, Germany and
² Med. Klinik II, Charite-Campus Charite Mitte, Berlin, Germany, and Robert Koch Institute, Berlin, Germany
³ Robert Koch Institute, Berlin, Germany
⁴ Med. Klinik II, Charite-Campus Charite Mitte, Berlin, Germany

^* To whom correspondence should be addressed. E-mail: stefan.biel{at}beiersdorf.com.

Background: We studied electron microscopy (EM) as an appropriate test system for the detection of polyomavirus in urine samples from bone marrow transplant patients.

Methods: We evaluated direct EM, ultracentrifugation (UC) before EM, and solid-phase immuno-EM (SPIEM). The diagnostic accuracy of EM was studied by comparison with a real-time PCR assay on 531 clinical samples.

Results: The detection rate of EM was increased by UC and SPIEM. On 531 clinical urine samples, the diagnostic sensitivity of EM was 47% (70 of 149) with a specificity of 100%. We observed a linear relationship between viral genome concentration and the proportion of urine samples positive by EM, with a 50% probability for a positive EM result for urine samples with a polyomavirus concentration of 10⁶ genome-equivalents (GE)/mL; the probability of a positive EM result was 0% for urine samples with <10³ GE/mL and 100% for urine samples containing 10⁹ GE/mL.

Conclusions: UC/EM is highly specific for polyomavirus in urine. Unlike real-time PCR, EM has low sensitivity and cannot quantify the viral load.