Cytologic and biomolecular diagnosis of polyomavirus infection in urine specimens of HIV-positive patients

OBJECTIVE: To evaluate the frequency of human polyomavirus reactivation in urine specimens from HIV-positive patients; compare the sensitivity of cyto logy, immunohistochemistry and molecular biology; differentiate viral genot ypes; and correlate the results with urinary cytologic abnormalities. STUDY DESIGN: Urine specimens from 78 unselected HIV-positive patients were evaluated by means of cytology, immunohistochemistry and nested polymerase chain reaction (n-PCR) to evaluate the presence of polyomaviruses. Restric tion fragment length polymorphism (RFLP) was carried out in positive cases in order to differentiate BK virus (BKV) from JC virus (JCV). CD4 cells and serum creatinine levels were evaluated as indices of immune status and ren al function, respectively, whereas the presence of red blood cells was used as an index of urogenital damage. RESULTS: Cytologic evidence of polyomavi rus infection was found in 17 samples and immunohistochemically confirmed i n 9; another 6 cytologically negative cases were detected by means of immun ohistochemistry. In all cases, only one or two cells showed typical viral i nclusions or positive staining. n-PCR identified 44 positive samples, thus confirming all of the cytologically and immunohistochemically positive case s and detecting polyomavirus genome in a further 21. RFLP detected 39 JCV, 1 BKV and 4 JCV-BKV infections. No correlation was found between the presen ce ou type of polyomavirus and immune status, but red blood cells were foun d mol frequently in the positive than in the negative samples. Serum creati nine levels fell within the normal range in all cases. CONCLUSION: Molecular biology is the most sensitive tool for detecting poly omavirus urinary infection in HIV-positive patients and the only reliable m ethod of differentiating JCV and BKV viral genotypes.