Early HHV-6 replication is associated with morbidity non-related to CMV infection after kidney transplantation

human herpesvirus type 6-(hhv-6) has been associated with morbidity after liver transplantation. objective: the aim of this study was to determine the hhv-6 seroprevalence among donor-recipient pairs, analyze the incidence of early active infection, its clinical manifestation, interaction with cmv, and the related morbidity in the first year after kidney transplantation. methods: 46 donor-recipient pairs had igg evaluated by elisa before transplantation: hhv-6(pambio - usa) and cmv-(roche - usa). a frozen whole blood sample collected weekly (from the 1st to the 6th week) was retrospectively tested for hhv-6 viral load (vl) determination by real time quantitative pcr (qpcr, nanogen - italy). patients were preemptively surveyed for cmv by pp65 antigenemia (ag, apaap, immunohistochemistry, biotest - germany) from the 4th to the 12th week after transplantation. active infection was defined as qpcr-hhv6+ (viral-load/ml-vl) and ag+ (+cells/100.000 granulocytes), for hhv-6 and cmv, respectively. dcmv was defined as simultaneous positive antigenemia and suggestive signs/symptoms. concerning +qpcr-hhv6, associated factors, clinical manifestation, interaction with cmv and morbidity were searched. results: pre-transplant hhv-6 seroprevalence was significantly higher among kidney recipients compared to their donors (82.6x54.8%; p = 0.005 [3.9 (1.4-10.4)]). active infection by this virus occurred in 26.1% (12/46), with no association with previous igg (p = 0.412). median vl was 125 copies/ml (53-11.264), and the median ag was 21 +cells (2-740). there was no association between hhv-6 and cmv activation after transplantation (p = 0.441), neither concerning dcmv (p = 0.596). median highest ag+ and days of ganciclovir treatment were similar between qpcr-hhv6 + or - (p = 0.206 and p = 0.124, respectively). qpcr-hhv6+ was associated with higher incidence of bacterial (p = 0.009) and fungal (p = 0.001) infections, and higher number (p = 0.001) of hospital admission and longer duration