Prospective Weekly Multiple Viral Monitoring in Blood Using Multiplex PCR Assay Early After Hematopoietic Stem Cell Transplantation

Viral infections remain serious complications after hematopoietic stem cell transplantation (HSCT), despite a remarkable progress of the prophylactic and treatment strategies. Detection of the early stage of viral reactivation and infection was extremely important as CMV antigenemia monitoring and pre-emptive therapy. In this study, we performed a prospective PCR-guided viral monitoring for 13 species and evaluate the association with actual onset of viral disease.

Patients and methods: Adult patients aged ≥ 16 years old who were scheduled for allogeneic or autologus HSCT were eligible for this study. Informed consent was obtained from all patients. From a week before transplantation to the 8 weeks after, the DNA quantity of 13 viral species was weekly measured using in-house multiplex PCR assays, which enable to simultaneously determine the amount of herpes simplex virus-1 (HSV-1), human simplex virus-2 (HSV-2), varicella-zoster virus (VZV), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) humanherpesvirus 6 (HHV-6), humanherpesvirus 7(HHV-7), humanherpesvirus 8 (HHV-8), parvovirus B19, hepatitis B virus (HBV), JC virus (JCV), BK virus (BKV), and adenovirus (ADV). As antiviral prophylaxis for HSV/VZV and HHV-6 diseases, oral acyclovir and intravenous foscarnet in all recipients and exclusively in those receiving unrelated cord blood, respectively, whereas antigenemia-guided preemptive therapy against CMV disease with ganciclovir or foscarnet was performed in allo-transplant settings.

A hundred patients who underwent HSCT at Toranomon Hospital from May to December 2010 were enrolled for this study. Median age was 52 (16–71) years old. Six patients who underwent autologous transplantation were included. In a total of 821 peripheral specimens obtained during the study period, HHV-6 was detected in 69.6%, CMV in 37.7%, BK in 13.2% and ADV in 7.7% of 471 PCR positive samples, and the detection rate of other virus was lower than 3.1%. The cumulative incidences of positive viral load due to HHV-6, CMV, BKV, ADV during the study period were 88.5%, 54.3%, 24.1%, and 11.6%. During the study period, 31 patients developed any viral infections with a cumulative incidence of 34.0%, at a median of 18 (-1-56) days after HSCT. Ten patients had 2 or more episodes of different viral infections, and a total of 45 infectious episodes were documented. HHV-6 encephalitis accounted for 33.3% of all viral infections during prophylactic foscarnet administration. Other common viruses included ADV 22.2 % (dissemination in 8, hemorrhagic cystitis (HC) in 2), and BKV 35.6 % (HC in all 22 patients). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were analyzed for common virus such as ADV, BKV and HHV-6. CMV was excluded CMV antigenemia-guided pre-emptive therapy successfully suppressed the onset of diseases. The sensitivity, specificity, PPV, and NPV for diagnosing ADV infections were 85.7%, 100.0%, 100.0% and 98.9%. These data suggest ADV monitoring is a useful strategy for predicting the onset of disease. The sensitivity, specificity, PPV, and NPV for diagnosing BKV associated HC were 61.1%, 86.6%, 50.0% and 91.0%, whereas those of the PCR assay with use of a threshold of 10000 copies/ml were 46.6%, 71.8%, 29.1% and 88.4% for diagnosing HHV-6 encephalitis.

Our multiple viral monitoring system using multiplex PCR assay was useful for detecting viral load kinetics for 13 species early after HSCT. As for ADV, viral load in blood detected in our assay had a high sensitivity and specificity for developing ADV infectious diseases. The sensitivity and specificity level for HHV-6 and BK was not as high as ADV because definite threshold level was not determined yet and HHV-6 encephalitis might be suppressed due to prophylactic foscarnet, these findings suggested that the multiplex PCR assay could be applied to the routine monitoring for viral infections in the early period after HSCT.

No relevant conflicts of interest to declare.