Association of HHV-6 and HHV-7 reactivation with the development of chronic allograft nephropathy

Background: The long-term effect of HHV-6 and HHV-7 infections on chronic allograft nephropathy (CAN) development after renal transplantation is uncertain. Objectives: To determine HHV-6 and HHV-7 reactivation during the post-transplantation period and to evaluate its effect on CAN development in renal transplant patients. Study design: Eighty-one renal allograft recipients (28 with CAN, 53 with normal transplant function) were studied to determine the frequency of HHV-6 and HHV-7 reactivation during 36.4 ± 7.8 months after renal transplantation using nested PCR. HHV-6 variants were identified using restriction endonuclease analysis. Patients were monitored for the development of CAN. Results: The frequency of HHV-6 and/or HHV-7 plasma DNA was significantly higher in CAN patients (25/28, 89.3%) compared to control patients (15/50, 30.0%, p = 0.0001). CAN patients also had an increased incidence of dual active infections (20/25, 80% and 2/15, 13.3%, p = 0.007, respectively). In all 34 HHV-6 positive cases, the HHV-6B variant was identified. The presence of HHV-7 DNA in plasma preceded the presence of HHV-6 DNA. Early development of CAN and graft loss was detected only in patients with simultaneous HHV-6 and HHV-7 plasma DNA. Conclusions: Reactivation of HHV-6 and HHV-7 in renal graft recipients is a risk factor for CAN development. The presence of concurrent HHV-6 and HHV-7 DNA in the plasma is an unfavorable prognostic factor.