Human herpesvirus 6 infection of human epidermal cell line: pathogenesis of skin manifestations

Human herpes virus 6 reactivation: important predictor for poor outcome after myeloablative, but not non-myeloablative allo-SCT

Hematopoietic SCT (HSCT) is often complicated by viral reactivations. In this retrospective cohort study (January 2004-August 2008), predictors for human herpes virus 6 (HHV6)-reactivation and associations between HHV6-reactivation and clinical outcomes after allogeneic HSCT were studied. HHV6 DNA load in plasma was monitored weekly by quantitative real-time PCR. Associations between the main end point HHV6-reactivation and other end points, that is, acute GVHD (aGVHD) and NRM were analyzed using Cox proportional hazard models. In total, 108 patients receiving either a myeloablative (MA; n=60) or non-myeloablative (NMA; n=48) conditioning regimen were included. Median age was 40 years (range 17-65); median follow-up was 20 months (range 3-36). In 16/60 (27%) patients with MA conditioning regimen, a HHV6 reactivation was observed (mean viral load 50 323 cp/mL) compared with 2/48 (4%) patients with a NMA conditioning regimen with low viral load (mean 1100 cp/mL). In multivariate analysis, MA conditioning was the only predictor for HHV6 reactivation (P=0.02). In addition, HHV6 reactivation was associated with grades 2-4 aGVHD (P<0.001) and NRM (P=0.03). Regular monitoring of HHV6 reactivation after HSCT might be important in MA HSCT patients to enable early initiation of antiviral treatment or to anticipate aGVHD, all of which may improve clinical outcome.

The complex relationship between human herpesvirus 6 and acute graft-versus-host disease

The most frequent manifestation of human herpesvirus 6 (HHV-6) reactivation after allogeneic hematopoietic stem cell transplantation (HSCT) is febrile rash, raising the question of its relationship with graft-versus-host disease (GVHD). In this retrospective analysis of 365 patients who underwent allogeneic HSCT, HHV-6 reactivation was significantly associated with cord blood transplantation (hazard ratio [HR], 3.20; P < .0001) and the use of unrelated donors (HR, 2.02; P = .008). On multivariate analysis, previous GVHD was a predictive factor for HHV-6 reactivation (HR, 1.80; P = .01), and previous HHV-6 reactivation was a predictive factor for acute GVHD (HR, 1.66; P = .03). Nineteen patients with no pathological evidence of GVHD later developed severe clinical GVHD (grade III-IV), suggesting the role of HHV-6 as a trigger for severe GVHD. Furthermore, 17 patients without histopathological GVHD demonstrated a significant lymphoid infiltrate suggesting "pure" HHV-6-related manifestations, and these patients could have been spared steroid therapy.

Human herpesvirus-6 and -7 in pediatric stem cell transplantation

BACKGROUND

Human herpesvirus-6 (HHV-6) and -7 (HHV-7) may reactivate with immunosuppression and cause symptoms varying from subclinical to severe organ manifestations. The presence of HHV-6 and -7 and their possible association with clinical problems among pediatric recipients of stem cell grafts was studied in a single institution setting between November 1999 and December 2001.

PROCEDURE

A total of 60 patients, mean age 8.5 years, were transplanted: 2/3 received allogeneic grafts and 1/3 autologous stem cell rescue. The presence of HHV-6 and -7 was studied in blood by polymerase chain reaction (PCR) (HHV-6) and antigenemia (HHV-6 and -7).

RESULTS

Both HHV-6 and -7 were frequently present in the blood of stem cell graft recipients. No significant difference in the incidence of HHV-6 or -7 reactivations between the allogeneic and autologous patients nor recipients of sibling or unrelated donor (URD) grafts was observed. HHV-6 antigenemia was associated with fever, rash, and delayed engraftment. Among symptomatic patients two cases of encephalitis were encountered with both having HHV-6 detectable in their cerebrospinal fluid (CSF) by PCR.

CONCLUSIONS

HHV-6 and -7 seem to be common in blood both pre- and post-transplant among pediatric recipients of stem cell grafts. Prolonged reactivations appear to correlate with clinical symptoms such as fever, rash, and bone marrow suppression in the post-stem cell transplant setting (SCT), but severe complications are rare. Transient reactivations appear to be of very limited clinical significance.

Human herpesvirus 6 variant B infection in adult patients after unrelated cord blood transplantation

Human herpesvirus 6 variant B (HHV-6B) infection was studied in 23 adult patients who underwent cord blood transplantation (CBT). HHV-6B DNA was detected by quantitative polymerase chain reaction analysis after CBT in the sera from 15 patients (65%) at day 14 or 15 (week 2), from 16 patients (70%) at day 21 or 22 (week 3), and from 3 patients (13%) at day 28 or 29 (week 4). HHV-6B DNAemia was found in none of the 20 patients examined at day 7 or 8 (week 1). The overall incidence of HHV-6B DNAemia reached 87% (20 of 23 patients). This incidence was much higher than after unrelated bone marrow transplantation (19%, P < .0001). In CBT patients, positive HHV-6B DNAemia at week 3 was significantly associated with early skin rash (88% versus 14%, P < .005) and grade II-IV acute graft-versus-host disease (aGVHD) (69% versus 14%, P < .05). In contrast, positive HHV-6B DNAemia at week 2 was associated with neither skin rash nor aGVHD. Prospective large-scale studies are needed to determine the role of HHV-6 infection in CBT patients.

Association of human herpesvirus type 6 DNA with human bladder cancer

We examined the presence of human herpesvirus type 6 (HHV6) DNA in a series of 74 bladder carcinomas from a Mediterranean population to elucidate their possible role as cofactor in the development of bladder cancer with or without associated human papillomavirus (HPV) infection. HHV-6 type B DNA was present in 5 men (6.8%) out of the 74 tumors investigated; two of them had associated HPV-16 DNA in the same specimen. In one case that had associated urothelial carcinoma in situ, both HHV-6B and HPV-16 DNA were present. In conclusion, the low incidence of HHV-6B in bladder cancer and the ubiquitous nature of HHV-6 infection are more consistent with a bystander role rather than cofactor in the oncogenesis of bladder cancer.