Tissue viral DNA is associated with chronic allograft nephropathy

Viral infections post-renal transplant (Tx) impact on outcome. Increased rejection rates and decreased renal function secondary to acute CMV, EBV and HHV-6 infections are well described. However, the clinical significance of a mere presence of these viruses on kidney tissue biopsy remains questionable. Thirty-six kidney biopsies obtained from 17 renal transplants (five females) and two combined liver-kidney recipients (one female) were retrospectively evaluated. Age at Tx ranged from 1.7 to 17.2 yr (median = 7.4). Biopsies were performed as protocol biopsies or when renal function deteriorated, between 6 weeks and 11 yr post-Tx (median = 1.2 yr). Immunosuppression included steroids and combination of tacrolimus/cyclosporin, mycophenolate mofetil/azathioprin and induction therapy. Fourteen patients received antiviral prophylaxis (ganciclovir/valganciclovir/acyclovir). Renal tissue was classified according to Banff '97 criteria. Tissue CMV, EBV, HHV-6 and HHV-7 was analyzed by PCR. We used an estimation of GFR from average plasma Cystatin C (CysC) and slopes of 1/CysC to assess renal function. The 16/36 biopsies were positive for one virus; 5/36 biopsies were positive for two viruses. In the infected group, Banff '97 scores for interstitial fibrosis (ci) and tubular degeneration/atrophy (ct) were significantly higher (p < 0.03 vs. the non-infected group for both). The slope of 1/CysC, or the proportion of patients on antiviral prophylaxis, did not differ significantly between both groups. In conclusion, a significant number of kidney biopsies showed PCR positivity for CMV, EBV, HHV-6 and HHV-7. This was associated with a significantly higher Banff score for ci and ct; while renal function was not affected. Further controlled studies are required.