Correlations of cytokine levels in cerebrospinal fluid and peripheral blood with outcome of HHV-6B encephalitis after hematopoietic stem cell transplantation.

BACKGROUND: Human herpesvirus (HHV)-6B encephalitis has been recognized as a serious complication after allogeneic hematopoietic cell transplantation (allo-HCT). Little is known about the pathogenic mechanism for its progression. STUDY DESIGN: We retrospectively evaluated the 16 kinds of cytokines and chemokines in cerebrospinal fluid (CSF) and plasma in patients who developed HHV-6B encephalitis. Among a total of 20 patients, 12 were categorized as the poor prognosis group (died of encephalitis; n = 8 and retained sequelae; n = 4), and other eight patients were categorized as the good prognosis group (complete recovery; n = 8). RESULTS: Concentrations of CSF IL-6 and IL-8 at the onset of encephalitis were significantly higher in the poor prognosis group than in the good prognosis group (median CSF IL-6, 28.27 pg/mL vs 14.32 pg/mL, P = .004; median CSF IL-8, 128.70 pg/mL vs 59.43 pg/mL, P = .043). Regarding plasma, the concentration of each cytokine at the onset of encephalitis was not significantly different between the two groups, except IL-5. However, higher levels of IL-6, IL-7, and MCP-1 and lower levels of IL-12 were observed 1 week before the development of encephalitis in patients with poor prognosis (median IL-6; 464.17 pg/mL vs 47.82 pg/mL, P = .02; median IL-12; 1.63 pg/mL vs 6.57 pg/mL, P = .03). CONCLUSION: We found that one week before onset of HHV-6B encephalitis, poor prognosis patients had high plasma concentrations of IL-6, IL-7, and MCP-1 and low concentrations of IL-12. At the onset of encephalitis, high concentrations of IL-6 and IL-8 in CSF were more common in the poor prognosis group, consistent with other evidence that IL-6 can have a role in CNS disturbances. Our findings show that specific cytokine status is associated with severe brain damage in patients with HHV-6B encephalitis, demonstrate prognostic value of plasma IL-6 concentrations, and suggest evaluation of anti-cytokine therapeutics in patients with HHV-6B encephalitis.

Human Herpesvirus 6B and Lower Respiratory Tract Disease After Hematopoietic Cell Transplantation.

PURPOSE: Human herpesvirus 6B (HHV-6B) DNA is frequently detected in bronchoalveolar lavage fluid (BALF) from immunocompromised subjects with lower respiratory tract disease (LRTD). Whether HHV-6B is a pulmonary pathogen is unclear. METHODS: We tested BALF for HHV-6B DNA using polymerase chain reaction in allogeneic hematopoietic cell transplantation (HCT) recipients who underwent a BAL for evaluation of LRTD from 1992 to 2015. We used multivariable proportional hazards models to evaluate the association of HHV-6B+ BALF with overall mortality, death from respiratory failure, and the effect of anti-HHV-6B antivirals on these outcomes. We used branched-chain RNA in situ hybridization to detect HHV-6 messenger RNA (U41 and U57 transcripts) in lung tissue. RESULTS: We detected HHV-6B+ BALF from 147 of 553 (27%) individuals. Subjects with HHV-6B+ BALF, with or without copathogens, had significantly increased risk of overall mortality (adjusted hazard ratio [aHR], 2.18; 95% CI, 1.41-3.39) and death from respiratory failure (aHR, 2.50; 95% CI, 1.56-4.01) compared with subjects with HHV-6B- BALF. Subjects with HHV-6B+ BALF who received antivirals within 3 days pre-BAL had an approximately 1 log10 lower median HHV-6B BALF viral load, as well as a lower risk of overall mortality (aHR, 0.42; 95% CI, 0.16-1.10), compared with subjects with HHV-6B+ BALF not receiving antivirals. We detected intraparenchymal HHV-6 gene expression by RNA in situ hybridization in lung tissue in all three tested subjects with HHV-6B+ BALF and sufficient tissue RNA preservation. CONCLUSION: These data provide evidence that HHV-6B detection in BALF is associated with higher mortality in allogeneic hematopoietic cell transplantation recipients with LRTD. Definitive evidence of causation will require a randomized prevention or treatment trial.

High human herpesvirus 6 viral load in pediatric allogeneic hematopoietic stem cell transplant patients is associated with detection in end organs and high mortality.

Human Herpes Virus 6 (HHV-6) reactivation occurs in approximately half of patients following allogeneic hematopoietic stem cell transplant (HSCT). While encephalitis and delayed engraftment are well-documented complications of HHV-6 following HSCT, the extent to which HHV-6 viremia causes disease in children is controversial. We performed a retrospective review of HHV-6 reactivation and possible manifestations in pediatric allogeneic HSCT patients at a single institution. Of 89 children and young adults who underwent allogeneic HSCT over a three-and-a-half-year period, 34 patients reactivated HHV-6 early post-transplant. Unrelated donor stem cell source and lack of antiviral prophylaxis were risk factors for the development of HHV-6 viremia. Viremia correlated with the presence of acute graft-versus-host disease, but not chronic graft-versus-host disease. We identified two subgroups within the viremic patients-a high-risk viremic and tissue-positive group that reactivated HHV-6 and had suspected end-organ disease and a low-risk viremic but asymptomatic group that reactivated HHV-6 but did not exhibit symptoms or signs of end-organ disease. Peak viral load was found to be strongly associated with mortality. Prospective studies in larger numbers of patients are needed to further investigate the role of HHV-6 in causing symptomatic end-organ disease as well as the association of viral load with mortality.

Impact of Human Herpesvirus-6 Reactivation on Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation.

Human herpesvirus-6 (HHV-6) is known to reactivate after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and may be associated with development of acute graft-versus-host disease (GVHD) and nonrelapse mortality (NRM). However, the clinical significance of HHV-6 reactivation after allo-HSCT remains unclear. Therefore, we conducted a retrospective analysis to elucidate the impact of HHV-6 reactivation on transplantation outcomes. Of 236 patients who underwent allo-HSCT, 138 (58.5%) developed HHV-6 reactivation and 98 (41.5%) did not. Univariate analysis indicated that at 3 years, patients with HHV-6 reactivation had significantly higher NRM (27.7% versus 13.7%, P = .003) and worse overall survival (42.1% versus 59.0%, P = .008) than those without reactivation. In multivariate analysis, HHV-6 reactivation was associated with higher incidence of acute GVHD (hazard ratio [HR], 1.87; P = .01), cytomegalovirus reactivation (HR, 2.24; P < .001), and NRM (HR, 2.73; P = .007). Subgroup analysis stratified according to conditioning intensity indicated that a significant impact of HHV-6 reactivation on acute GVHD was observed only in patients who received myeloablative conditioning (MAC). These results indicate that HHV-6 reactivation was associated with development of acute GVHD, cytomegalovirus reactivation, and NRM. Furthermore, adverse impact of HHV-6 reactivation on transplantation outcomes was prominent in the setting of MAC.

Human herpesvirus 6 reactivation before engraftment is strongly predictive of graft failure after double umbilical cord blood allogeneic stem cell transplantation in adults.

Our main objective was to determine new factors associated with engraftment and single-unit predominance after double umbilical cord blood (UCB) allogeneic stem-cell transplantation. Engraftment occurred in 78% of cases in this retrospective study including 77 adult patients. Three-year overall survival, disease-free survival, relapse incidence, and nonrelapse mortality were 55 ± 6%, 44 ± 6%, 33 ± 5%, and 23 ± 4%, respectively. In multivariate analysis, Human herpesvirus 6 reactivation during aplasia (hazard ratio [HR] = 2.63; 95% confidence interval [CI]: 1.64-4.17; p < 0.001), younger recipient age (<53 years) (HR = 1.97; 95% CI: 1.16-3.35; p = 0.012), and lower human leukocyte antigen matching between the two units (3 of 6 or 4 of 6) (HR = 2.09; 95% confidence interval: 1.22-3.59; p = 0.013) were the three factors independently associated with graft failure. Also, factors independently predicting the losing UCB unit were younger age of the UCB unit (odds ratio [OR] = 1.01; 95% CI: 1-1.02; p = 0.035), lower CD34(+) cell dose contained in the UCB unit (≤ 0.8 × 10(5)/kg) (OR = 2.55; 95% CI: 1.05-6.16; p = 0.04), and presence of an ABO incompatibility between the UCB unit and the recipient (OR = 2.53; 95% CI: 1.15-5.53; p = 0.02). Thus, Human herpesvirus 6 reactivation during aplasia, lower unit-unit human leukocyte antigen matching, and younger UCB unit age, as new unfavorable predictive factors, may represent new parameters to take into account after double UCB allogeneic stem-cell transplantation in adults. These results need to be confirmed prospectively, as they may influence unit selections and patient outcomes.

Fludarabine and exposure-targeted busulfan compares favorably with busulfan/cyclophosphamide-based regimens in pediatric hematopoietic cell transplantation: maintaining efficacy with less toxicity.

Busulfan (Bu) is used as a myeloablative agent in conditioning regimens before allogeneic hematopoietic cell transplantation (allo-HCT). In line with strategies explored in adults, patient outcomes may be optimized by replacing cyclophosphamide (Cy) with or without melphalan (Mel) with fludarabine (Flu). We compared outcomes in 2 consecutive cohorts of HCT recipients with a nonmalignant HCT indication, a myeloid malignancy, or a lymphoid malignancy with a contraindication for total body irradiation (TBI). Between 2009 and 2012, 64 children received Flu + Bu at a target dose of 80-95 mg·h/L, and between 2005 and 2008, 50 children received Bu targeted to 74-80 mg·h/L + Cy. In the latter group, Mel was added for patients with myeloid malignancy (n = 12). Possible confounding effects of calendar time were studied in 69 patients receiving a myeloablative dose of TBI between 2005 and 2012. Estimated 2-year survival and event-free survival were 82% and 78%, respectively, in the FluBu arm and 78% and 72%, respectively, in the BuCy (Mel) arm (P = not significant). Compared with the BuCy (Mel) arm, less toxicity was noted in the FluBu arm, with lower rates of acute (noninfectious) lung injury (16% versus 36%; P = .007), veno-occlusive disease (3% versus 28%; P = .003), chronic graft-versus-host disease (9% versus 26%; P = .047), adenovirus infection (3% versus 32%; P = .001), and human herpesvirus 6 infection reactivation (21% versus 44%; P = .005). Furthermore, the median duration of neutropenia was shorter in the FluBu arm (11 days versus 22 days; P < .001), and the patients in this arm required fewer transfusions. Our data indicate that Flu (160 mg/m(2)) with targeted myeloablative Bu (90 mg·h/L) is less toxic than and equally effective as BuCy (Mel) in patients with similar indications for allo-HCT.

Risk factors for human herpesvirus 6 reactivation and its relationship with syndrome of inappropriate antidiuretic hormone secretion after stem cell transplantation in pediatric patients.

There have been several reports on the reactivation of human herpesvirus 6 (HHV6) after stem cell transplantation (SCT) in adults, which sometimes induces severe illness. Few reports exist on pediatric patients; therefore, we retrospectively examined HHV6 reactivation after SCT in children. We reviewed 80 patients with a median age of 6 years. We analyzed HHV6 DNA serum samples from the patients before SCT and at 20 and 40 days after SCT using polymerase chain reaction. We also analyzed the relationship between HHV6 reactivation and the syndrome of inappropriate antidiuretic hormone secretion (SIADH). At 20 days after SCT, 35.0% of serum samples were positive for HHV6 DNA. The median viral load was 3.1×10 copies/mL serum. Multivariate analysis showed cord blood transplantation as the only risk factor for HHV6 reactivation. HHV6 reactivation occurs in 59.4% of 32 patients who underwent cord blood transplantation and in 18.8% of 48 patients who underwent SCT from other sources. Among the 14 patients with SIADH, 78.6% experienced HHV6 reactivation. Among the 66 patients without SIADH, only 25.8% had HHV6 reactivation. This result was statistically significant (P<0.001). This analysis revealed that HHV6 reactivation occurs in many children. In addition, HHV6 reactivation plus SIADH should prompt evaluation for central nervous system disease.

Human herpesvirus type 6 DNAemia and infection following allogeneic stem cell transplantation with a focus on long-term outcome.

Cases of human herpesvirus type 6 (HHV-6) infection and disease were retrospectively analysed in a cohort of 97 allogeneic haematopoietic stem cell transplantation (allo-SCT) patients in Gothenburg, Sweden (1997-2001). Altogether 54 of 97 (56%) patients were tested for HHV-6. HHV-6 DNAemia was detected in 15 of the tested patients at a median of 76 (range 24-387) days after SCT. Nine of these patients were treated against HHV-6 infection and disease for a total of 11 treatment episodes. The morbidity associated with HHV-6 DNAemia following allo-SCT was in most cases moderate. The overall 1-y survival among the patients with HHV-6 DNAemia was 11/15 (73%) and the 5-y survival was 10/15 (67%), which was not significantly different from the whole cohort.

Human herpesvirus-6 encephalitis during hematopoietic stem cell transplantation leads to poor prognosis.

INTRODUCTION: Indications for the application of hematopoietic stem cell transplantation (HSCT) from alternative donors have remarkably broadened in scope; however, the incidence of infections that lead to failure of HSCT, such as human herpesvirus-6 (HHV-6) encephalitis, has also increased. METHODS: We analyzed risk factors for symptomatic HHV-6 reactivation and the development of HHV-6 encephalitis in 140 consecutive adult patients who received allogeneic HSCT at our institution. Stem cell sources for the recipients were as follows: related-donor bone marrow in 40, related-donor peripheral blood in 5, unrelated bone marrow in 67, and unrelated cord blood in 28. RESULTS: Symptomatic HHV-6 reactivation occurred in 22 patients (16%), and 11 patients manifested encephalitis. Multivariate Cox proportional hazards regression analysis identified cord blood cell transplantation (CBT) as an independent predictor of HHV-6 reactivation (P = 0.008). Hyponatremia or hypernatremia at the time of HHV-6 reactivation was detected before the development of HHV-6 encephalitis in 2 or 4 patients, respectively. Two patients died of HHV-6 encephalitis and 6 patients died of relapse of underlying diseases. Survival analysis identified higher risk of the disease (P = 0.021) and HHV-6 encephalitis (P = 0.003) as independent risk factors for reduced overall survival. CONCLUSION: In cases involving CBT or unrelated-donor transplantation, patients should be carefully monitored for the symptomatic reactivation of HHV-6.

HHV-6 encephalitis in umbilical cord blood transplantation: a systematic review and meta-analysis.

Reactivation of human herpesvirus-6 (HHV-6) frequently occurs following hematopoietic SCT (HSCT), and has been associated with clinical consequences in many patient populations. HHV-6 reactivation and HHV-6 encephalitis seem to occur more frequently in patients undergoing HSCT with cord blood (CB) as the stem cell source. We have conducted a systematic literature review and meta-analysis to investigate the clinical significance of this correlation. A systematic review of publications indexed in PubMed was performed for HSCT studies published over the past 10 years that fit inclusion criteria. Data on prevalences of HHV-6 reactivation and HHV-6 encephalitis post HSCT were abstracted from 19 papers. Meta-analyses were conducted to calculate combined prevalence estimates. The prevalences of HHV-6 reactivation and encephalitis were compared among CB vs non-CB HSCT. Prevalences of HHV-6 reactivation and HHV-6 encephalitis were significantly higher in patients receiving CB as the stem cell source than in patients receiving another stem cell source (72.0% vs 37.4%, P<0.0001; 8.3% vs 0.50%, P<0.0001, respectively). HHV-6 reactivation and HHV-6 encephalitis are significant complications in the post-HSCT setting, particularly in patients receiving CB as the stem cell source. Thus, patients undergoing umbilical CB transplantation should be closely monitored for HHV-6 reactivation.

Early human herpesvirus type 6 reactivation after allogeneic stem cell transplantation: a large-scale clinical study.

This study investigated the impact of human herpesvirus type 6 (HHV6) reactivation within 100 days of allogeneic stem cell transplantation (allo-SCT) on patient outcomes. HHV6 plasma loads were monitored weekly by quantitative PCR. Of 235 consecutive patients, 112 (48%) had an early positive HHV6 PCR test (group A) and 123 (52%) did not (group B). HHV6 reactivation was less frequent in patients who received reduced-intensity conditioning (P = .028). In group A, only 6 patients (5%) were asymptomatic; the most common clinical manifestations were fever (n = 60), skin rash (n = 57), diarrhea (n = 51), pulmonary complications (n = 19), and neurologic disorders (n = 12). Compared with the patients in group B, those in group A experienced delayed platelet engraftment (P = .003) and more frequent grade II-IV acute graft-versus-host disease (GVHD) (47% versus 30% in group B; P = .009). In multivariate analysis, the most important factors influencing the development of grade II-IV acute GVHD development were early HHV6 reactivation (P = .03) and unrelated donor status (P < .001). HHV6 reactivation adversely influenced 6-month survival (P = .04). Of the 38 evaluable patients receiving antiviral treatment, 34 had a significantly decreased HHV6 load. Our findings indicate that HHV6 reactivation after allo-SCT is associated with delayed platelet engraftment, early posttransplantation mortality, and the development of acute GVHD. Careful monitoring of HHV6 by PCR is warranted during the early posttransplantation period.

Human herpesvirus 6 infection after hematopoietic cell transplantation: is routine surveillance necessary?

Human herpesvirus 6 (HHV6) may be an important pathogen following allogeneic hematopoietic cell transplantation (HCT). We prospectively evaluated weekly HHV6 viremia testing after allogeneic HCT using a quantitative polymerase chain reaction (PCR)-based assay. HHV-6 viremia was detected in 46 of 82 (56%) patients at a median of 23 days post-HCT (range: day +10 to +168). More males (65% vs females 39%, P = .03) and recipients of umbilical cord blood (UCB 69% vs unrelated donor [URD], 46% vs sibling donor [20%] grafts, P = 0.01) reactivated HHV-6. Patients with HHV6 viremia had more cytomegalovirus (CMV) reactivation (26% vs 5.5%, P = .01) and unexplained fever and rash (23.9% vs 2.7%, P = .01) compared with patients without HHV6 viremia. High-level HHV6 (≥ 25,000 copies/mL) versus lower levels were associated with more culture-negative pneumonitis (72.7% vs 22.8%, P = .01). Twenty HHV6-positive patients were treated with foscarnet, ganciclovir, or cidofovir for HHV6 or other coexistent viruses. Within 2 weeks, HHV6 viremia resolved more commonly in treated (65%) than untreated patients (31%), P = .02. Survival at 3 months was similar in treated and untreated patients (90% vs 81%, P = .4). Survival at 3 and 6 months post-HCT were not affected by HHV6 positivity (3 months HHV6+ 85% vs 78%, P = .46; 6 months HHV6+ 70% vs 72%, P = .89) or by HHV6 level (3-month high level 73% vs 89%, P = .23; 6-month high level 64% vs 71%, P = .54). Neither the occurrence of HHV6, degree of viremia, nor use of antiviral drugs influenced short-term survival after HCT.

Detection of ß-herpesviruses in Polish adult cord blood stem cell recipients by real-time PCR: single centre study.

Umbilical cord blood transplantation (UCBT) is known to be associated with increased risk of infections, compared to bone marrow or peripheral blood stem cell transplantation. In viral diseases for which specific treatment is available, real-time PCR assays are reliable diagnostic tools for timely initiation of appropriate therapy and for rapid assessment of the efficacy of antiviral treatment strategies. A retrospective review of samples from a group of seven adult cord blood stem cell recipients was made. Serum samples taken up to 180 days after transplantation were examined with quantitative real-time PCR for measurement of viral load (CMV, HHV-6, and HHV-7). Cytomegalovirus (CMV) DNA was detected in samples taken from four patients (57%) in the period of 20-80 days after transplantation. Products of amplification of human herpesvirus 6 (HHV-6) DNA were found in samples taken between days 25 and 37 following UCBT from only one patient (14%). On the other hand, the majority of patients (n = 6, 86%) had HHV-7 DNA detected in the period 15-58 days after transplantation. Co-infection with HHV-7 was demonstrated at onset of all episodes of microbiologically confirmed CMV or HHV-6 infection. Our observations indicate that real-time PCR is not only useful for monitoring herpesviral infections in transplant recipients, but is also a powerful method for clarifying the relationships between the viral load and clinical symptoms. Further investigation with a much larger group of patients will be needed to confirm these observations and translate them into a clinical approach.

Human herpesvirus 6 meningoencephalitis in allogeneic hematopoietic stem cell transplant recipients.

We retrospectively investigated the clinical characteristics of human herpesvirus 6 (HHV-6) meningoencephalitis within 100 days after allogeneic hematopoietic stem cell transplantation (HSCT). Of 1148 patients who received transplants between January 1999 and December 2003, 11 patients (0.96%) with HHV-6 meningoencephalitis were identified. Ten of 11 recipients received hematopoietic stem cells from donors other than HLA-identical siblings. Confusion was the most frequent central nervous system (CNS) symptom, and a skin rash with high-grade fever preceded the CNS symptoms in 9 patients. Magnetic resonance imaging of the brain showed an abnormal increased T2 signal in the hypothalamus of 5 patients. Eight patients were treated with ganciclovir, and an improvement of CNS symptoms was obtained in 3 patients; 3 patients treated with acyclovir showed no improvement. Improvement in the meningoencephalitis seemed less frequent in patients with abnormal findings in the hypothalamus than in those without such findings. Because the symptoms of HHV-6 meningoencephalitis mimicked those of cyclosporine- or tacrolimus-induced encephalopathy, the drugs were withdrawn at the onset of CNS symptoms in 10 patients, resulting in the development of grade IV graft-versus-host disease (GVHD) in 5 patients. Three patients died of HHV-6 meningoencephalitis, and 6 died of other causes, including GVHD. In conclusion, HHV-6 meningoencephalitis is a rare but potentially life-threatening complication in patients who undergo allogeneic HSCT. Careful assessment of the clinical findings and the brain may allow early and precise diagnosis of HHV-6 meningoencephalitis and contribute to improving its prognosis.

Human herpesvirus 6 in bronchalveolar lavage fluid after lung transplantation: a risk factor for bronchiolitis obliterans syndrome?

Bronchiolitis obliterans syndrome (BOS) is the limiting factor to long-term survival after lung transplantation. Previous studies suggested respiratory viral tract infections are associated with the development of BOS. To identify the impact of virus detection in bronchoalveolar lavage (BAL) fluid, we analyzed BAL samples from 87 consecutive lung transplant recipients for human herpesvirus (HHV)-6, Epstein-Barr virus, Herpes simplex virus 1/2, Cytomegalovirus, respiratory syncytical virus and adenovirus by PCR. Acute rejection, BOS and death were recorded for a mean follow-up time of 3.27 +/- 0.47 years. Results of PCR analysis and other potential risk factors were entered into a Cox regression analysis of BOS predictors and death. Only acute rejection was a distinct risk factor for BOS of all stages, death and death from BOS. HHV-6 was detected in 20 patients. Univariate and multivariate analysis revealed that HHV-6 was associated with an increased risk to develop BOS > orb = stage 1 and death, separate from the risk attributable to acute rejection. Identification of HHV-6 DNA in BAL fluid is a potential risk factor for BOS. Our results warrant further studies to elucidate a possible causal link between HHV-6 and BOS.

Preconception vaccination with a glycoprotein B (gB) DNA vaccine protects against cytomegalovirus (CMV) transmission in the guinea pig model of congenital CMV infection.

DNA vaccines expressing the guinea pig cytomegalovirus (GPCMV) homologs of the glycoprotein B (gB) and UL83 proteins were evaluated for protection against congenital GPCMV infection. After 4 doses of DNA administered by epidermal (gene gun) route, all guinea pigs developed enzyme-linked immunosorbent assay (ELISA) antibody and, for gB-vaccine recipients, neutralizing antibody. Dams were challenged with 1 x 10(4) plaque-forming units of GPCMV in the third trimester. Preconception vaccination with gB did not decrease overall pup mortality, although, within the gB-vaccine group, pup mortality was lower among dams with high ELISA responses. Preconception maternal vaccination with gB vaccine significantly reduced congenital transmission in liveborn pups. In contrast, UL83 vaccine had no significant effect on pup mortality or vertical transmission of GPCMV. Virus load was significantly lower in infected pups born to gB- and UL83-vaccinated dams than in infected pups born to control dams. These data support the concept that subunit gB vaccination may be useful in protecting against CMV-induced disease.

Human herpesvirus-6 infection after lung and heart-lung transplantation: a prospective longitudinal study.

BACKGROUND: Although human herpesvirus (HHV)-6 is now recognized as a frequent pathogen after transplantation, the real impact of this infection in patients undergoing transplantation remains unclear. METHODS: During 27 months, 30 consecutive heart-lung- and lung-transplant recipients were included on the day of transplantation and prospectively followed during 100 days for HHV-6 infection. RESULTS: HHV-6 infection occurred in 20 (66%) patients after a median delay of 18 days after transplantation. The virus was detected by polymerase chain reaction or culture, or both, in 15.7 % of blood specimens, in 14.5% of bronchoalveolar lavage fluids, and in many organs at postmortem examination; it was found by culture in eight patients. No clinical manifestations could clearly be associated with HHV-6 alone. However, patients with HHV-6 infection had a higher mortality rate than patients without HHV-6 infection (7 of 20 vs. 0 of 10; P=0.04), and all the deceased patients died during periods of HHV-6 infection. We did not observe higher incidence of infectious or graft-rejection episodes in HHV-6-positive patients. However, eight of nine viral or fungal infections occurred during HHV-6 infection and three were directly responsible for death. CONCLUSION: Although frequently detected after transplantation, HHV-6 was not associated with any specific clinical manifestation. The higher mortality rate observed in patients with HHV-6 infection was not related to a higher incidence of bacterial infections or graft rejection but might be associated with more viral and fungal infections.

High incidence of human herpesvirus 6 infection with a high viral load in cord blood stem cell transplant recipients.

Human herpesvirus 6 (HHV-6) infection in recipients of cord blood stem cell transplants (CBSCTs) was estimated by semiquantitative and real-time quantitative polymerase chain reaction (PCR) and reverse-transcription PCR. Of the CBSCT recipients, 7 (70%) of 10 had active HHV-6 infection after transplantation, and all 7 were inferred from their age to have already had a primary infection. Because HHV-6 DNA is seldom detected in cord blood, these cases were considered likely to represent reactivation. In contrast, the 3 patients without HHV-6 infection were all believed to be naive regarding HHV-6 primary infection because of their age and the results of PCR assays given before the transplantation procedure. The incidence of HHV-6 infection after transplantation was significantly higher (P <.05) than after bone marrow (BM) transplantation and peripheral blood stem cell (PBSC) transplantation, when recipients without primary HHV-6 infection prior to transplantation were excluded (CBSCT, 100%; BMT/PBSCT, 56.3%). Real-time PCR revealed a higher level of viral DNA in the peripheral blood mononuclear cells from CBSCT recipients than from BMT/PBSCT recipients or patients with exanthem subitum (P <.05). HHV-6 mRNA of the U79/80 gene was also detected by reverse-transcription PCR in all analyzed patients with HHV-6 infection. Its detection was correlated with the emergence of viral DNA in the plasma and symptoms such as fever and rash. Thus, HHV-6 infection was more frequent and the viral load was higher in CBSCT recipients with prior primary infection.

Ganciclovir is effective for prophylaxis and treatment of human herpesvirus-6 in allogeneic stem cell transplantation.

Human herpesvirus 6 (HHV-6) infection and disease are serious complications of allogeneic hematopoietic stem cell transplantation (allo-SCT). Ganciclovir (GCV) is effective against HHV-6 in vitro but the antiviral susceptibility of HHV-6 has not been well characterized in vivo. We retrospectively compared the HHV-6 reactivation rate in pediatric allo-SCT recipients with and without GCV prophylaxis. The HHV-6 reactivation rate at 3 weeks after allo-SCT in patients without prophylactic GCV administration was significantly higher than that in those receiving prophylactic GCV (11/28 vs 0/13, P < 0.01). Five of 36 patients without prophylactic GCV showed clinical manifestations including skin rash, interstitial pneumonitis, persistent thrombocytopenia, enterocolitis and thrombotic microangiopathy, respectively. HHV-6-associated symptoms were observed in one of the 13 patients receiving prophylactic GCV. This patient showed fever, diarrhea and graft rejection concomitantly with a sudden increase of HHV-6 DNA copy number. Patients who received GCV for treatment of HHV-6 infection showed an improvement in symptoms and/or decrease of HHV-6 copy number. Thus, GCV is effective for treating HHV-6 disease after allo-SCT in vivo.