Human polyomavirus infection in renal allograft recipients

Cytological and virological studies on 74 patients with functioning renal allografts were undertaken to detect polyomavirus infection of the renal tract. Ten patients (13.5%) were excreting polyomavirus. Virus particles were seen in the electron microscope in urine samples from eight patients. B.K. polyomavirus was isolated from four patients. Infection with a different polyomavirus was probable in one patient. Virus isolation was most readily achieved when large numbers of intact virus particles were seen in the urine. Patients who were excreting large amounts of polyomavirus shed numerous inclusion-bearing cells which could be detected by cytology. A serological study showed that the prevalence of B.K. antibody was similar to that found in the general population and 38% of this series of transplant patients had evidence of active infection with B.K. virus.