Human Herpesvirus 6 DNA in Plasma after Allogeneic Stem Cell Transplantation: Incidence and Clinical Significance

Abstract

Active HHV-6 infection is not rare in SCT recipients. SCT from allelic-mismatch donors is associated with increased risk of active HHV-6 infection. Steroid therapy is associated with not only increased incidence of infection but also accelerated viral replication. Development of limbic encephalitis is associated with high HHV-6 DNA load.

Human herpesvirus-6 encephalitis after allogeneic hematopoietic cell transplantation: What we do and do not know

“…PCR testing of hair follicles or nails for HHV-6 DNA can confirm ciHHV-6 status in recipients. 35 CLINICAL PRESENTATION AND DIAGNOSIS: WE KNOW CLINICAL FEATURES OF TYPICAL HHV-6 ENCEPHALITIS, BUT DO NOT KNOW THE VARIABILITY OF ITS PRESENTATION HHV-6 encephalitis typically develops ∼ 2-6 weeks after allo-HCT, [3][4][5]36,37 and symptoms often include delirium, amnesia, confusion, ataxia and seizure. The most typical initial symptom is memory loss with subsequent progression to confusion and loss of consciousness.…”

“…The most typical initial symptom is memory loss with subsequent progression to confusion and loss of consciousness. 3,36,37 Overt seizures, including generalized seizures and partial seizures, develop in 40-70% of patients. [36][37][38] HHV-6 encephalitis may accompany syndrome of inappropriate antidiuretic hormone.…”

“…[38][39][40] HHV-6 encephalitis typically shows an MRI signature of hyperintense lesions on T2-weighted, fluid-attenuated inversion recovery imaging and diffusion-weighted imaging of bilateral medial temporal lobes, primarily affecting the hippocampus and amygdala (Figure 1). 3,7,[36][37][38]41,42 Some investigators have termed this finding 'post-transplant acute limbic encephalitis (PALE) 38,40,[42][43][44] and HHV-6 PALE has been diagnosed when the patient has detectable HHV-6 DNA in cerebrospinal fluid in the context of acute-onset altered mental status, amnesia, seizures or other evidence of medial temporal lobe disease involving the limbic system and no other identifiable etiology. 38,42 A recent retrospective study 45 showed, however, not all cases of HHV-6-associated CNS dysfunction meet the criteria for PALE.…”

“…Reactivation of human herpesvirus-6 (HHV-6) is common after allogeneic hematopoietic cell transplantation (allo-HCT), [1][2][3][4][5] and is sporadically associated with the development of HHV-6 encephalitis. 1,[3][4][5][6][7][8] The first case of HHV-6 encephalitis after allo-HCT was described in 1994 by Drobyski et al 9 Since then, a significant amount of information regarding the incidence, risk factors, therapy and outcomes has been reported.…”

“…1,[3][4][5][6][7][8] The first case of HHV-6 encephalitis after allo-HCT was described in 1994 by Drobyski et al 9 Since then, a significant amount of information regarding the incidence, risk factors, therapy and outcomes has been reported. Over the past decade, HHV-6 encephalitis has become well known as a significant complication of allo-HCT.…”