Inherited chromosomally integrated Human herpesvirus 6 in patients with blood system diseases

Introduction . Human herpesvirus 6 (HHV-6) is an opportunistic agent causing various complications in patients with hematological diseases. The virus has a unique ability to integrate into telomeres of human chromosomes, which makes hereditary transmission of the viral genome possible. This form of the virus is called inherited chromosomally integrated HHV-6 (iciHHV-6). The iciHHV-6 frequency among patients with blood system diseases is unknown and its signifi cance for clinical practice remains insufficiently studied. Aim — to determine the prevalence of ichHHV-6 in patients with hematological diseases. Materials and methods . Clinical and laboratory data in 4,998 adult patients treated at the National Medical Research Center for Hematology (Moscow, Russia) from 2020 to 2024 were analyzed. Clinical materials obtained from patients were examined by molecular-biological methods for the presence of HHV-6 DNA. Results . IciHHV-6 was confirmed in 14 out of 4,998 (0.26 %) enrolled patients. 5 patients (38,5 %) had clinical manifestations of herpesvirus infection during treatment, while the other 9 patients (61.5 %) showed no signs of the infection. 5 of 14 iciHHV-6-positive patients underwent hematopoietic stem cell transplantation. Criteria and laboratory tests for suspicion for iciHHV-6 were designed and successfully verified, which made it possible to suspect and prove the presence of hci-HCV-6. Conclusion . The presence of ichHHV-6 among patients with hematological diseases was detected in 0.26 % of cases. The high concentration of HCV-6 DNA during polymerase chain reaction testing, as well as the absence of negative virological results during antiviral therapy, make it possible to suspect HCV-HCV-6. Screening for iciHHV-6 by qPCR of hair follicles and nails is recommended for patient with high viremia. A positive result in such tests confirms iciHHV-6-positive status. The efficiency of antiviral therapy in iciHHV-6-individuals requires further research. During transplantation of allogeneic hematopoietic stem cells to a recipient-carrier of hci-HCV-6, HCV-6 reactivation, asymptomatic persistence of high viremia, and a dramatic decrease of the viral load are all possible.