Analysis of the shedding of three β-herpesviruses DNA in Polish patients subjected to allogeneic hematopoietic stem cell transplantation: Six-year follow up.

Background: Infections with human β-herpesviruses are common worldwide and are still frequent in patients after hematopoietic stem cell transplantation. Some data suggest that HHV-6 and HHV-7 could take part in CMV reactivation from latency and/or progression of CMV disease in immunosupressed patients.

Objectives: The aims of this study were: (1) to summarise retrospectively the results of β-herpesviruses DNA detection in a large group of adult allogeneic haematopoietic stem cell transplant recipients; and (2) to find a potential correlation between viruses belonging to this subfamily.

Study Design: AlloHSCT recipients (N=142) were examined in the early post-transplant period (median=89 days). The presence of CMV, HHV-6 and HHV-7 was confirmed through detection and quantification of viral DNA, isolated from 1679 sera samples.

Results: CMV DNA alone was detected in 23.9% of patients, while single HHV-6 and HHV-7 were detected in 14.8% and 9.9% of individuals, respectively. The reactivation of more than one virus was identified in 31% of analysed patients. In cases of concurrent infection, HHV-7 was detected at the same time as HHV-6, and both of them were usually reactivated before CMV. The kinetics of virus reactivation and measured viral load may suggest a potential role of HHV-6 and HHV-7 as co-factors in CMV reactivation.

Conclusions: The observed kinetics of virus reactivation may strongly suggest a potential role of HHV-6 and/or HHV-7 as co-factors of CMV reactivation. The co-infection with these β-herpesviruses could predispose patients after hematopoietic stem cell transplantation to a longer and more severe CMV infection.