Mysore KR, Phan TL, Himes RW, et al. - Researchers sought to report on differences between HHV-6 primary infection in seronegative patients and HHV-6 reactivation in seropositive patients in pediatric liver transplant (LT) recipients. Pretransplant serology testing of HHV-6 was implemented in a large pediatric hospital and retrospective assessment of the incidence, manifestations and outcomes of HHV-6 infections over a 3-year period was done. Pretransplant HHV-6 serologies were available for 96 of 101 pediatric LT recipients; 34 (35.4%) were seronegative and 62 (64.6%) seropositive. Seronegative pediatric LT recipients more frequently had HHV-6 DNA-emia, usually in the early posttransplant period, and its subsequent detection was observed in allograft biopsies. In the absence of allograft tissue testing and specialized virological assays, ruling out of HHV-6 as a cause of hepatitis is not possible, as HHV-6 may disrupt local allograft immune homeostasis while evading traditional screening methods using blood or plasma. They suggest possible relevance of assessment of pre-transplant HHV-6 serological status for risk stratification and posttransplant management of pediatric LT recipients