Factors determining the course of BK viral (BKV) infection remain uncertain. We studied the role of BKV subtype distribution in BKV-infected patients after renal transplantation.-

We performed genotyping of BKV subtypes in 180 BKV-infected renal transplant recipients with BKV nephropathy (BKVN, n=69), BKV viremia (n=94), BKV viruria alone (n=17), and in 29 healthy adults and 11 dialysis patients with spontaneous BKV replication in urine. We then tested, if the frquency of certain subtypes corresponded to the severity of the infection: BKV nephropathy, BKV high viremia (>10000 copies/mL), or BKV low viremia (<10000 copies/mL). –

Ib-2 was the most frequent BKV subtype (135/220. 61%) and subtype IV the second in frequency (50/220, 23%); Ib-1 (10%), Ia (5%), II and III (1%) were less frequent. Subtype IV-infected patients had more often BKVN and/or high viremia of >10000 copies/mL than patients with other subtypes (31/38 versus 78/125, p=0.02). Patients with low viremia of <10000 copies/mL were less often infected with subtype IV than patients with BKVN and/or high viremia (7/38 versus 16/38, p=0.03). The mean maximal viral load of patients infected with subtype IV (n=38) was significantly higher than that of patients with other subtypes (n=125) (7.6+/-20.1mill versus 2.0+/-9.1mill copies/mL, p=0.02). Renal function of patients infected with subtype IV (n=36) deteriorated more during 2 years of follow-up after transplantation than that of patients infected with other subtyypes (n=116) (mean loss of GFR -7.44+/-18.7 versus -3.57+/-16.84mL/min, p=0.002).

Thus, BKV subtype IV was more often associated with BKVN and/or high viremia and less often with low viremia; subtype IV had a higher maximal viral load; and patients with subtype IV had more decline of renal function during follow-up after renal transplantation. Subtype IV may be one of the viral determinants.

CITATION INFORMATION: Anke S, Silvia L, Hermann H, Albert H, Corinna S. Impact of BKV Subtype Distribution on BKV Nephropathy, Viremia, and Renal Outcome in Patients After Renal Transplantation. Am J Transplant. 2016;16 (suppl 3).

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