Association Between the Polyomaviruses Titers and Decoy Cell Positivity Rates After Renal Transplantation.

BACKGROUND: Urinary decoy cells develop after renal transplantation and their appearance is attributable primarily to the proliferation of polyomavirus types BK and JC. We measured the levels of these 2 viruses that cause decoy cells to appear in the urine.

PATIENTS AND METHODS: BK and JC virus levels were quantified in 1182 urine samples from 335 renal transplant patients using a multiplex Taqman real-time polymerase chain reaction assay. Forty-four samples were excluded from analyses because both viruses were present at ≥10(4) copies/mL. We analyzed the relationship between viral load and the presence of urinary decoy cells.

RESULTS: Decoy cells were observed in 237 of 1138 urine samples (21%) and the BK and JC viruses were positive in 205 (18%) and 455 (40%) samples, respectively. Decoy cells were observed in 0%, 21%, 67%, 87%, 100%, and 96% of urine samples when the BK viral load was <10(4), 10(4)-10(5), 10(5)-10(6), 10(6)-10(7), 10(7)-10(8), and ≥10(8) copies/mL, respectively; and in 1%, 13%, 41%, 59%, 87%, and 97% of urine samples when the JC viral load was <10(4), 10(4)-10(5), 10(5)-10(6), 10(6)-10(7), 10(7)-10(8), and ≥10(8) copies/mL, respectively.

CONCLUSIONS: BK virus more frequently triggered the appearance of decoy cells than did JC virus at equivalent viral titers.