HHV-6 Reactivation after Hematopoietic Stem Cell Transplantation in Chinese Patients Is Associated with aGVHD.

Recent reports indicate that human herpesvirus (HHV)-6 reactivation occurs in 40–65% of patients undergoing hematopoietic stem cell transplantation (HSCT).But the complication after HSCT that predispose to HHV-6 viremia are not well characterized. The aim of our research is to study the potential relationship between HHV-6 activation and acute graft-versus-host disease (aGVHD) after hematopoietic cell transplantation (HSCT) in chinese patients. Peripheral blood samples were collected before and weekly after HSCT from 40 consecutive recipients who underwent HSCT between March 2005 and Joungry 2007 (2 autologous and 38 allogeneic transplants) .HHV-6 DNAemia was monitored by real-time PCR. The genotypes of HHV-6 were identified by Hind III restriction assay. Of the 40 patients, HHV-6 DNAemia were detected in only 1 patient (2.5%) before HSCT, and the viral load was 420 copies/ml.After HSCT there were 18(45%) patients detected HHV-6 DNA on a median of day 14.5 (range, 0– 23 days), and the median HHV-6 viral load of 4884.4±374.4 copies/ml (range, 282 – 43400 copies/ml). Respectively, HHV-6B was identified as the predominant variant.Grade I – IV aGHVD occurred in 18 (45%) on a median of day 20 (range, 8–40 days). The median onset time of HHV-6 DNAemia was significantly earlier than that of aGHVD (P <0.05). Compared with that in HHV-6 DNAemia positive [HHV-6(+)] patients, the cumulative incidence of grade I – IV aGHVD was higher (72.2% vs. 27.7%, P <0.05) than in negative [HHV-6(−)] patients. Cumulative incidence of grade I – IV aGVHD was higher in patients with both HHV-6 and CMV positive (CMV+/HHV-6+) than in those with either CMV (CMV+/HHV-6−) or HHV-6 positive (CMV−/HHV-6+) and neither of them positive (CMV−/HHV-6−) [66.7% (10/15),26.7% (4/15) ,66.7% (2/3) and 28.6% (2/7), respectively, P<0.05]. Our data suggest that patients who undergo HSCT are at significant risk for HHV-6 reactivation. HHV-6 viremia occurs early during the post-transplant course, most often within the first 2 weeks. Patients with HHV-6 activation or HHV-6/CMV co-infection maybe involved in the occurrence of aGVHD after HSCT.