Tetrameric glycoprotein complex gH/gL/gQ1/gQ2 is a promising vaccine candidate for human herpesvirus 6B.

Primary infection of human herpesvirus 6B (HHV-6B) occurs in infants after the decline of maternal immunity and causes exanthema subitum accompanied by a high fever, and it occasionally develops into encephalitis resulting in neurological sequelae. There is no effective prophylaxis for HHV-6B, and its development is urgently needed. The glycoprotein complex gH/gL/gQ1/gQ2 (called 'tetramer of HHV-6B') on the virion surface is a viral ligand for its cellular receptor human CD134, and their interaction is thus essential for virus entry into the cells. Herein we examined the potency of the tetramer as a vaccine candidate against HHV-6B. We designed a soluble form of the tetramer by replacing the transmembrane domain of gH with a cleavable tag, and the tetramer was expressed by a mammalian cell expression system. The expressed recombinant tetramer is capable of binding to hCD134. The tetramer was purified to homogeneity and then administered to mice with aluminum hydrogel adjuvant and/or CpG oligodeoxynucleotide adjuvant. After several immunizations, humoral and cellular immunity for HHV-6B was induced in the mice. These results suggest that the tetramer together with an adjuvant could be a promising candidate HHV-6B vaccine.

Leukocytoclastic Vasculitis Associated with HHV6-A/ciHHV6-A and HHV6-B Coinfection in an Immunocompetent Woman.

BACKGROUND AND OBJECTIVE: Leukocytoclastic vasculitis (LCV) is a small vessel vasculitis that can be limited to the skin but may also affect other organs. Often, its cause is unknown. LCV has previously been reported to occur with the reactivation of human herpesvirus 6 (HHV-6). Here, we report a second instance of HHV-6 reactivation in a 43-year-old woman with idiopathic cutaneous LCV. CASE DESCRIPTION: In this case, the patient was immunocompetent, and testing revealed that she had inherited chromosomally integrated human herpesvirus 6 variant A (iciHHV6-A) with a parallel skin infection of HHV-6B. The integrated ciHHV-6A strain was found to be transcriptionally active in the blood, while HHV-6B late antigen was detected in a skin biopsy. The patient's rash was not accompanied by fever nor systemic symptoms and resolved over four weeks without any therapeutic intervention. CONCLUSION: In light of the transcriptional activity documented in our case, further examination of a possible role for HHV-6 in the etiology of LCV is warranted.

Cytokine and cellular responses to human herpesvirus-6B in patients with B-acute lymphoblastic leukemia.

Primary infection with human herpesvirus-6 (HHV-6), is followed by its lifelong persistence in the host. Most T-cell responses to HHV-6 have been characterized using peripheral blood from healthy adults; however, the role of HHV-6 infection in immune modulation has not been elucidated for some diseases. Therefore, in this study the immune response to HHV-6 infection in patients with B-acute lymphoblastic leukemia (B-ALL) was analyzed. HHV-6 load was quantified in blood samples taken at the time of diagnosis of leukemia and on remission. The same concentrations of anti- and pro-inflammatory cytokines (IL-4, IL-1, IL-6, IL-8, IL-12p70, IL-17a, TNF-α and IFN-γ) were detected in plasma samples from 20 patients with and 20 without detectable HHV-6 virus loads in blood. Characterization of T-cell responses to HHV-6 showed low specific T-cells frequencies of 2.08% and 1.46% in patients with and without detectable viral loads, respectively. IFN-γ-producing T cells were detected in 0.03%-0.23% and in 0%-0.2% of CD4+T cells, respectively. Strong production of IL-6 was detected in medium supernatants of challenged T-cells whatever the HHV-6 status of the patients (973.51 ± 210.06 versus 825.70 ± 210.81 pg/mL). However, concentrations of TNF-α and IFN-γ were low. Thus, no association between plasma concentrations of cytokines and detection of HHV-6 in blood was identified, suggesting that HHV-6 is not strongly associated with development of B-ALL. The low viral loads detected may correspond with latently infected cells. Alternatively, HHV-6B specific immune responses may be below the detection threshold of the assays used.

Human Herpesvirus 6 Infection Following Haploidentical Transplantation: Immune Recovery and Outcome.

Human herpesvirus 6 (HHV-6) is increasingly recognized as a potentially life-threatening pathogen in allogeneic hematopoietic stem cell transplantation (alloSCT). We retrospectively evaluated 54 adult patients who developed positivity to HHV-6 after alloSCT. The median time from alloSCT to HHV-6 reactivation was 34 days. HHV-6 was present in plasma samples from 31 patients, in bone marrow (BM) of 9 patients, in bronchoalveolar lavage fluid and liver or gut biopsy specimens from 33 patients, and in cerebrospinal fluid of 7 patients. Twenty-nine patients developed acute graft-versus-host disease (GVHD), mainly grade III-IV, and 15 had concomitant cytomegalovirus reactivation. The median absolute CD3+ lymphocyte count was 207 cells/µL. We reported the following clinical manifestations: fever in 43 patients, skin rash in 22, hepatitis in 19, diarrhea in 24, encephalitis in 10, BM suppression in 18, and delayed engraftment in 11. Antiviral pharmacologic treatment was administered to 37 patients; nonetheless, the mortality rate was relatively high in this population (overall survival [OS] at 1 year, 38% ± 7%). A better OS was significantly associated with a CD3+ cell count ≥200/µL at the time of HHV-6 reactivation (P = .0002). OS was also positively affected by the absence of acute GVHD grade III-IV (P = .03) and by complete disease remission (P = .03), but was not significantly influenced by steroid administration, time after alloSCT, type of antiviral prophylaxis, plasma viral load, or organ involvement. Although HHV-6 detection typically occurred early after alloSCT, better T cell immune reconstitution seems to have the potential to improve clinical outcomes. Our findings provide new insight into the interplay between HHV-6 and the transplanted immune system.

Exanthem subitum (human herpesvirus-6 reactivation) after autologous stem cell transplantation.

We present the case of a 62-year-old man treated with high-dose chemotherapy and consecutive autologous stem cell transplantation for mantle cell lymphoma, who developed high fever and a rash of the trunk and both axillae 10 days after stem cell transplantation.

Copy numbers of telomeric repeat sequences of human herpesvirus 6B in clinical isolates: possibility of mixed infections.

In order to determine whether mixed infections of human herpesvirus 6B (HHV-6B) occur in immunocompetent and immunocompromised individuals, we examined the copy numbers of telomeric repeat sequences (TRS) of clinical isolates. In clinical isolates obtained from patients with exanthem subitum caused by primary HHV-6B infection, PCR products with HHV-6B TRS ranging between 400 and 800 bp were amplified. PCR products of various sizes were amplified in four clinical isolates from drug-induced hypersensitivity syndrome (DIHS) patients and 15 isolates from hematopoietic stem cell transplant (HSCT) recipients with HHV-6B reactivation. Based on the sequence analysis of the PCR products, the copy numbers of TRS in DIHS and HSCT patients were between 42 and 82 and 22 and >90, respectively. For two of the HSCT recipients, HHV-6B TRS PCR products of different sizes were detected in several isolates from each patient, which suggests mixed HHV-6B infections. In two of the posttransplant HHV-6B encephalitis patients, the sizes of the TRS nested PCR products amplified from the reactivated virus detected in the central nervous system differed from those of the virus detected in initial isolates from peripheral blood mononuclear cells. Taken together, these results suggest that PCR analysis of TRS copy number is a reliable tool for the discrimination of HHV-6B clinical isolates. Additionally, mixed HHV-6B infections occurred in HSCT recipients, and in some cases, compartmentalization of the HHV-6B strains to the central nervous system versus the blood compartment occurred in posttransplant HHV-6B encephalitis patients.

Development of quantitative RT-PCR assays for detection of three classes of HHV-6B gene transcripts.

The monitoring of active human herpesvirus 6 (HHV-6) B infection is important for distinguishing between the reactivation and latent state of the virus. The aim of this present study is to develop a quantitative reverse transcription polymerase chain reaction (RT-PCR) assay for diagnosis of active viral infection. Primers and probes for in house quantitative RT-PCR methods were designed to detect the three kinetic classes of HHV-6B mRNAs (U90, U12, U100). Stored PBMCs samples collected from 10 patients with exanthem subitum (primary HHV-6B infection) and 15 hematopoietic stem cell transplant recipients with HHV-6B reactivation were used to evaluate reliability for testing clinical samples. Excellent linearity was obtained with high correlation efficiency between the diluted RNA (1-100 ng/reaction) and C(t) value of each gene transcript. The U90 and U12 gene transcripts were detected in all of the peripheral blood mononuclear cells (PBMCs) samples collected in acute period of primary HHV-6B infection. Only one convalescent PBMCs sample was positive for the U90 gene transcript. Additionally, the reliability of HHV-6B quantitative RT-PCRs for diagnosis of viral reactivation in hematopoietic transplant recipients was evaluated. Relative to virus culture, U90 quantitative RT-PCR demonstrated the highest assay sensitivity, specificity, positive predictive value, and negative predictive value. Thus, this method could be a rapid and lower cost alternative to virus culture, which is difficult to perform generally, for identifying active HHV-6B infection.

Diagnosis of human herpesvirus 6B primary infection by polymerase chain reaction in young children with exanthematic disease / Diagnóstico de infecção primária pelo herpesvírus humano tipo 6B através da técnica de reação em cadeia da polimerase em crianças com doença exantemática

INTRODUCTION: Exanthem subitum is a classical rash disease of early childhood caused by human herpesvirus 6B (HHV-6B). However, the rash is frequently misdiagnosed as that of either measles or rubella. METHODS: In this study, a nested multiplex polymerase chain reaction (PCR) was used to diagnose HHV-6B primary infection, differentiate it from infections caused by HHV-6A and compare it to antibody avidity tests. The samples were separated into case group and control group according to the results of the indirect immunofluorescence assay (IFA) technique. RESULTS: From the saliva samples analyzed, HHV-6A DNA was detected in 3.2 percent of the case group and in 2.6 percent of the control group. Regarding HHV-6B, PCR detected viral DNA in 4.8 percent of the case group and in 1.3 percent of the control group. Among the serum samples studied, a frequency of 1.7 percent was determined for HHV-6A in the case group and 1.2 percent in the control group. PCR did not detect HHV-6B DNA in serum samples. The sensitivity and specificity of the PCR technique ranged from 0 percent to 4.8 percent and 97.5 percent to 100 percent, respectively, compared to IFA. CONCLUSIONS: The PCR technique was not suitable for diagnosing primary infection by HHV-6B in children with exanthematic disease and should not substitute the IFA.

INTRODUÇÃO: O exantema súbito é uma doença comum durante a infância e pode ser causada pela infecção por herpesvirus humano tipo 6B (HHV-6B). No entanto, a erupção cutânea característica dessa doença, é frequentemente confundida com outras viroses como sarampo ou rubéola. MÉTODOS: Foi utilizada a técnica de reação em cadeia da polimerase (PCR) no formato nested multiplex para o diagnóstico de infecção primária por HHV-6B, diferenciação entre as infecções causadas pelo HHV-6A e comparação com testes de avidez de anticorpos. As amostras foram separadas em grupo caso e grupo controle, de acordo com os resultados do teste de imunofluorescência indireta (IFA). RESULTADOS: Nas amostras de saliva analisadas, o DNA do HHV-6A foi detectado em 3,2 por cento no grupo caso e em 2,6 por cento das amostras do grupo controle. Em relação ao HHV-6B, o DNA viral foi observado em 4,8 por cento no grupo caso e em 1,3 por cento no grupo controle. Após a realização da PCR nas amostras de soro, o DNA do HHV-6A foi detectado em 1,7 por cento no grupo caso e em 1,2 por cento no grupo controle, enquanto o DNA do HHV-6B não foi detectado. A sensibilidade e a especificidade da técnica de PCR variaram de 0 por cento a 4,8 por cento e de 97,5 por cento a 100 por cento, respectivamente, quando comparado com a IFA. CONCLUSÕES: A técnica de PCR não se mostrou adequada para o diagnóstico de infecção primária pelo HHV-6B em crianças com doença exantemática e não deve substituir a IFA.

The DRESS syndrome: a literature review.

The Drug Reaction with Eosinophilia and Systemic Symptom (DRESS) is a severe adverse drug-induced reaction. Diagnosing DRESS is challenging due to the diversity of cutaneous eruption and organs involved. We used the RegiSCAR scoring system that grades DRESS cases as "no," "possible," "probable," or "definite" to classify cases reported in the literature. We also analyzed the clinical course and treatments of the cases. A total of 44 drugs were associated with the 172 cases reported between January 1997 and May 2009 in PubMed and MEDLINE. The most frequently reported drug was carbamazepine, and the vast majority of cases were classified as "probable/definite" DRESS cases. Hypereosinophilia, liver involvement, fever, and lymphadenopathy were significantly associated with "probable/definite" DRESS cases, whereas skin rash was described in almost all of the cases, including "possible cases." Culprit drug withdrawal and corticosteroids constituted the mainstay of DRESS treatment. The outcome was death in 9 cases. However, no predictive factors for serious cases were found. This better knowledge of DRESS may contribute to improve the diagnosis and management of this syndrome in clinical practice.

[Lymphohistiocytic activation syndrome and Burkholderia cepacia complex infection in a child revealing chronic granulomatous disease and chromosomal integration of the HHV-6 genome]. / Syndrome d'activation lymphohistiocytaire associé à une infection àBurkholderia cepacia complex chez un nourrisson révélant une granulomatose septique et une intégration génomique du virus HHV-6.

Chronic granulomatous disease (GCD) is characterized by severe infections, notably with Burkholderia cepacia complex (BCC). GCD is rarely complicated by lymphohistiocytic activation syndromes, most often secondary to bacterial or viral infections, in particular human herpes virus 6 (HHV-6). We describe the case of a 10-month-old boy who suffered from multiple organ failure due to a BCC infection and a lymphohistiocytic activation syndrome, leading to diagnosis of GCD. The initial search for HHV-6 was positive and the infection was treated, but the progression and viral sample analysis led to the chromosomal integration of the HHV-6 genome. The child's clinical condition was normal after bone marrow transplantation. This case describes a rare association between GCD and lymphohistiocytic activation syndrome and raises questions about the role played by chromosomal integration of the HHV-6 genome.

[Human herpesvirus 6]. / Az emberi 6-os herpeszvírus.

Human herpesvirus 6 discovered in 1986 is the most ancient human herpesvirus shown by molecular characteristics. Variant B infects children under the age of 2 years by droplets from asymptomatic virus shedding adults occasionally causing exanthema subitum. The virus infects CD4+ macrophages and lymphocytes; subsequently establishes lifelong latency and persistence with occasional shedding through the saliva. This variant frequently reactivates in bone marrow and organ transplant recipients with concomitant immunosuppression causing even fatal complications. It is a cofactor in the pathogenesis of multiple sclerosis, chronic fatigue syndrome, Hodgkin and non-Hodgkin lymphomas. The direct consequences of variant A infection and latency in CD4+ cells are not known. It transactivates HIV infection in vitro and in humans, and facilitates tumor progression induced by human papilloma viruses. Pathogenic effects of both variants are mediated by altered cytokine and chemokine profiles. Serological differentiation of the two variants is unreliable; however, it is possible by using PCR. Ganciclovir, foscarnet and cidofovir can be used for treatment and chemoprophylaxis of severe complications.

Drug-induced hypersensitivity syndrome with rapid hematopoietic reconstitution during treatment for acute myeloid leukemia.

Drug-induced hypersensitivity syndrome (DIHS) is a rare but severe life-threatening, drug-induced, systemic hypersensitivity reaction. We report two patients who developed DIHS during treatment for acute myeloid leukemia. Awareness of DIHS is necessary when systemic eruptions and high fever occur in leukemic patients, especially with rapid hematopoietic recovery after chemotherapies.

Time course characteristics of human herpesvirus 6 specific cellular immune response and natural killer cell activity in patients with exanthema subitum.

The time-course of cell-mediated immunity in exanthema subitum is not well documented. The lymphoproliferative response to purified human herpesvirus 6 (HHV-6) antigen and to phytohemagglutinin was measured and natural killer (NK) cell activities determined in three consecutive specimens obtained biweekly from 18 young children and infants with exanthema subitum. Virus isolation and PCR detection of virus DNA and determination of neutralization antibody to HHV-6 and -7 were also carried out. The magnitude of the HHV-6 specific lymphoproliferative response varied; however, in most cases the time course kinetics revealed a low response in the acute phase with a subsequent gradual increase. In contrast, NK cell activities were high in the acute phase and declined gradually during convalescence. The lymphoproliferative response to phytohemagglutinin did not show a consistent trend in kinetics of time; however, dynamic changes in activity were observed in patients during the acute and convalescent periods. The results suggest that NK cells play a major role in resolving acute phase infection while specific lymphocyte activity develops later. The cause of the delayed development of HHV-6 specific lymphoproliferative response is unknown. The lymphoproliferative response to phytohemagglutinin ratios implied that HHV-6 infection has some impact on host T-cell immunity during the course of exanthema subitum.

Strong interaction between human herpesvirus 6 and peripheral blood monocytes/macrophages during acute infection.

Human herpesvirus 6 (HHV-6) encodes a viral chemokine and chemokine receptors that may modify the functions of monocytes/macrophages (MO/M phi) during productive HHV-6 infection. The interactions between HHV-6 and MO/M phi during acute infection, however, remain poorly understood. In this study, we investigated the tropism of HHV-6 in peripheral blood mononuclear cells (PBMCs) during acute infection. We detected 637 +/- 273 copies of viral DNA in 10(4) MO/M phi. in contrast, in 10(4) CD4+ T cells, which have been reported to be viral carriers during the acute infection of HHV-6, we found only 115 +/- 42 copies of viral DNA. Consistent with these data, virus was isolated from MO/M phi an order of magnitude more frequently than from CD4+ T cells. Viral mRNA U79/80, which indicates viral replication, was detectable in the MO/M phi. In addition, the mRNAs that encode viral chemokine receptors U12 and U51, which may modify the function of MO/M phi, were expressed in the cells. Therefore, productively infected MO/M phi may be the dominant cell population that is responsible for HHV-6 viremia during acute HHV-6 infection. The strong interaction of HHV-6 with MO/M phi may be partly responsible for the pathogenesis of this virus.

Antibody status to HHV-6 in children with leukaemia.

Forty children with acute lymphoblastic (33) or myeloid leukaemia (seven) were studied for IgG and IgM antibodies and IgG avidity against human herpesvirus 6 (HHV-6) at the time of diagnosis, and compared with age-, sex- and season-matched children with various neurological diseases of suspected viral origin. Of the children with leukaemia, 97.5% had IgG antibodies and 40% IgM antibodies to HHV-6 compared with 92.3% and 7.7% of reference subjects (P = 0.005). A seronegative child with leukaemia seroconverted 3 weeks after the diagnosis. The avidity of IgG antibodies (based on the resistance to urea treatment) was high in all children with leukaemia. One reference child had HHV-6-specific IgG antibodies with low avidity, which together with his positive IgM indicated an acute infection. The presence of specific IgM antibodies in 40% of children with leukaemia and the high avidity of IgG suggest a reactivation or an inaproppriate primary response to HHV-6 infection. The results support the conclusion of the role of the HHV-6 infection at the onset of childhood leukaemia.

[Etiopathogenic importance of human herpes viruses type 6, 7 and 8 in manifestations of certain skin diseases]. / Etiopatogenetski znacaj humanih herpes virusa tip 6, 7 i 8 u pojavi nekih oboljenja koze.

INTRODUCTION: In the past few years new human herpes viruses (HHV): HHV-6, -7 and -8 have been discovered. According to the most recent literature, they might have an important role in etiopathogenesis of some dermatological diseases. HUMAN HERPESVIRUS 6: HHV-6 was isolated in 1984 from peripheral blood lymphocytes of AIDS patients and patients with different lymphoproliferative diseases. Up to now, two variants of this virus have been identified, A and B, which differ in genetic, biological and immunological characteristics. The etiological importance of variant A, has not yet been clarified, while variant B is considered to be the major cause of many diseases, such as exanthema subitum in infants. In many cases primary infection is associated with elevated temperature, without rash. HUMAN HERPESVIRUS 7: HHV-7 was isolated in 1990 from activated peripheral blood CD4+ T cells of healthy persons. The virus is ubiquitous and more than 80% of babies and infants are affected. Presence of DNA sequences of this virus in mononuclear cells of peripheral blood, skin and plasma of pityriasis rosea patients, points to possible connection between this illness and HHV-7 infection. HUMAN HERPESVIRUS 8: HHV-8 was first identified in tissue samples of patients with Kaposi's sarcoma associated with AIDS in 1994. DNA virus sequences were also isolated in HIV negative persons with Kaposis's sarcoma. Presence of virus can be established in mononuclear cells of peripheral blood, endothelial cells that cover vascular spaces and spindle cells within skin changes. Modes of transmission are still not clarified. However, HHV-8 was identified in some other dermatological diseases as well.

[HHV 6,7 and 8. Recently discovered herpesviruses explain the etiology of well-known diseases]. / HHV 6, 7 och 8. Nyupptäckta herpesvirus förklarar etiologin till välkända sjukdomar.

Three new members of the family of human herpesviruses (HHVs) have been identified in less than a decade, HHV 67 and 8. HHV-6 and HHV-7, both infecting T-lymphocytes and phylogenetically related to cytomegalovirus, were identified as causative agents of exanthema subitum. In addition, HHV-6 has been reported to manifest central nervous system tropism and to be frequently detected in normal brain tissue, but has also been associated with febrile seizures. HHV-7 has been suggested to be involved in the development of pityriasis rosea, but has also been found to occur in normal dermal tissue. HHV-8, related to Epstein-Barr virus and infecting B-lymphocytes, was the first herpesvirus to be identified with molecular techniques. Recent research has been focused on the involvement of proteins expressed by HHV-8 in the pathogenesis of two rare tumours, Kaposi's sarcoma and body-cavity B-cell lymphomas.