Summary of the 9th international conference on human herpesviruses 6 and 7 (HHV-6A, HHV-6B, and HHV-7).

The 9th International Conference on Human herpesviruses 6 and 7 (HHV-6A, HHV-6B, and HHV-7) was held at Harvard Medical School in Boston, Massachusetts from November 9 to 11, 2015. Important new information was presented regarding: the biology of these viruses, particularly HHV-6A and HHV-6B; the biology and epidemiology of inherited chromosomally integrated HHV-6A/B; improved diagnostic tests; animal models for studying HHV-6 and HHV-7, and animal viruses with similarities to HHV-6 and HHV-7; established and possible disease associations; and new approaches to treatment. Here, we summarize work of particular interest. J. Med. Virol. 88:2038-2043, 2016. © 2016 Wiley Periodicals, Inc.

N-glycosylation of asparagine 8 regulates surface expression of major histocompatibility complex class I chain-related protein A (MICA) alleles dependent on threonine 24.

NKG2D is an activating receptor expressed on several types of human lymphocytes. NKG2D ligands can be induced upon cell stress and are frequently targeted post-translationally in infected or transformed cells to avoid immune recognition. Virus infection and inflammation alter protein N-glycosylation, and we have previously shown that changes in cellular N-glycosylation are involved in regulation of NKG2D ligand surface expression. The specific mode of regulation through N-glycosylation is, however, unknown. Here we investigated whether direct N-glycosylation of the NKG2D ligand MICA itself is critical for cell surface expression and sought to identify the essential residues. We found that a single N-glycosylation site (Asn(8)) was important for MICA018 surface expression. The frequently expressed MICA allele 008, with an altered transmembrane and intracellular domain, was not affected by mutation of this N-glycosylation site. Mutational analysis revealed that a single amino acid (Thr(24)) in the extracellular domain of MICA018 was essential for the N-glycosylation dependence, whereas the intracellular domain was not involved. The HHV7 immunoevasin, U21, was found to inhibit MICA018 surface expression by affecting N-glycosylation, and the retention was rescued by T24A substitution. Our study reveals N-glycosylation as an allele-specific regulatory mechanism important for regulation of surface expression of MICA018, and we pinpoint the residues essential for this N-glycosylation dependence. In addition, we show that this regulatory mechanism of MICA surface expression is likely targeted during different pathological conditions.

Cerebral Vasculitis in X-linked Lymphoproliferative Disease Cured by Matched Unrelated Cord Blood Transplant.

UNLABELLED: Vasculitis occurs rarely in association with X-linked lymphoproliferative disease (XLP). There are four published cases of non-EBV XLP-associated cerebral vasculitis reported, none of whom have survived without major cognitive impairment. CASE: A 9-year old boy initially presented aged 5 years with a restrictive joint disease. He subsequently developed dysgammaglobulinemia, episodic severe pneumonitis, aplastic anaemia, gastritis and cerebral vasculitis. A diagnosis of XLP was made, based on flow cytometric analysis and the identification of a novel mutation in SH2D1A, c.96G>C. No peripheral blood lymphocyte clonal proliferation was identified and he was EBV negative, although human herpes virus-7 (HHV7) was detected repeatedly in his cerebrospinal fluid. He underwent a reduced intensity unrelated umbilical cord blood transplant, but failed to engraft. A second 5/6 matched cord gave 100 % donor engraftment. Complications included BK virus-associated haemorrhagic cystitis, a possible NK-cell mediated immune reconstitution syndrome and post-transplant anti-glomerular basement membrane disease, the latter treated with cyclophosphamide and rituximab. At +450 days post-transplant he is in remission from his vasculitis and anti-glomerular basement membrane disease, and HHV-7 has remained undetectable. CONCLUSION: This is the second published description of joint disease in XLP, and only the fourth case of non-EBV associated cerebral vasculitis in XLP, as well as being the first to be successfully treated for this manifestation. This case raises specific questions about vasculitis in XLP, in particular the potential relevance of HHV-7 to the pathogenesis.

Persistent pityriasis rosea: an unusual form of pityriasis rosea with persistent active HHV-6 and HHV-7 infection.

Pityriasis rosea (PR) is an acute, self-limiting exanthematous disease, associated with the reactivation of the human herpesvirus 6 (HHV-6) and/or human herpesvirus 7 (HHV-7) that usually lasts 6-8 weeks. We studied, from a clinical and virological point of view, 12 patients in whom the features of PR lasted longer than 12 weeks, defining this form of the disease as persistent PR (PPR). As in typical PR, in most of the PPR patients the disease begins with a herald patch, but compared to typical PR, systemic symptoms and oral lesions are more common. Moreover, in PPR we found a persistent reactivation of HHV-6 and/or HHV-7 with higher viral loads than in typical PR, accounting for the unusual persistence of the illness, the more frequent and severer systemic symptoms and the oral lesions. In conclusion, we describe an unusual persistent form of PR, whose prevalence has probably been underestimated so far and which should be added to the other variants of PR.

Pityriasis Rosea in Children: Clinical Features and Laboratory Investigations.

Pityriasis rosea (PR) is a common, self-limiting exanthematous disease associated with a systemic reactivation of human herpesvirus 6 (HHV-6) and/or HHV-7. It usually occurs in the second or third decade of life whereas it is uncommon in patients younger than 10 years. We studied the clinical features and virological parameters of 31 children with PR, comparing them with those in adults. Our findings indicate that PR presents different characteristics between children and adults, mainly consisting of time lapse between herald patch and generalized eruption, duration of the exanthem, oropharyngeal involvement and persistence of HHV-6 and HHV-7 plasma viremia. Overall, these results suggest that, following HHV-6 and/or HHV-7 systemic active infection, the pathogenetic mechanisms involved in PR may at least partly be different in children and adults.

The human herpesvirus-7 (HHV-7) U21 immunoevasin subverts NK-mediated cytoxicity through modulation of MICA and MICB.

Herpesviruses have evolved numerous immune evasion strategies to facilitate establishment of lifelong persistent infections. Many herpesviruses encode gene products devoted to preventing viral antigen presentation as a means of escaping detection by cytotoxic T lymphocytes. The human herpesvirus-7 (HHV-7) U21 gene product, for example, is an immunoevasin that binds to class I major histocompatibility complex molecules and redirects them to the lysosomal compartment. Virus infection can also induce the upregulation of surface ligands that activate NK cells. Accordingly, the herpesviruses have evolved a diverse array of mechanisms to prevent NK cell engagement of NK-activating ligands on virus-infected cells. Here we demonstrate that the HHV-7 U21 gene product interferes with NK recognition. U21 can bind to the NK activating ligand ULBP1 and reroute it to the lysosomal compartment. In addition, U21 downregulates the surface expression of the NK activating ligands MICA and MICB, resulting in a reduction in NK-mediated cytotoxicity. These results suggest that this single viral protein may interfere both with CTL-mediated recognition through the downregulation of class I MHC molecules as well as NK-mediated recognition through downregulation of NK activating ligands.

Herpesvirus infections and allergic sensitization in children of families with anthroposophic and non-anthroposophic lifestyle - the ALADDIN birth cohort.

BACKGROUND: Growing up in families with an anthroposophic lifestyle has been associated with reduced risk of allergic disease in children. The aim of this report was to assess whether children with this lifestyle are infected earlier with Epstein-Barr virus (EBV), which has been associated with reduced risk of allergic disease, and three other herpesviruses potentially involved in allergy development, namely Human herpesvirus 6 (HHV6), Human herpesvirus 7 (HHV7) and cytomegalovirus (CMV). METHODS: Within the ALADDIN (Assessment of Lifestyle and Allergic Disease During Infancy), birth cohort study 157 children were categorized according to lifestyle into anthroposophic and non-anthroposophic. IgG-levels for EBV, HHV6, HHV7 and CMV were determined in plasma samples collected at ages 12 and 24 months and from parents. IgE levels against seven common allergens were analyzed at 24 months. RESULTS: No significant differences in seroprevalence of EBV, HHV7 or CMV were detected at any age between the two lifestyle groups. The seroprevalence of HHV6 was significantly lower in the anthroposophic group at 24 months of age (74.6% vs. 87.5%, p-value 0.048). Further, no significant associations between allergic sensitization and seropositivity to any of the viruses were detected; however, an interaction effect of lifestyle could not be ruled out. CONCLUSIONS: Our results indicate that there is no strong influence of exposure to the anthroposophic lifestyle on the time for infection with EBV, HHV6, HHV7 or CMV. These infections can therefore not be assumed to be important factors in the allergy-protective effect of this lifestyle.

Correlation of cytomegalovirus and human herpesvirus 7 with CD3+ and CD3+ CD4+ cells in chronic periodontitis patients.

BACKGROUND AND OBJECTIVE: Human chronic periodontitis is an inflammatory process characterized by dense accumulation of immune cells in the periodontal tissue. The periodontitis can lead to loss of teeth in the patient and the pathogenesis of this disease is not completely known. This study tested the hypothesis that chronic periodontitis-affected sites can harbor betaherpesviruses and that viruses are linked to a profile of the inflammatory infiltrate. MATERIAL AND METHODS: Biopsies of periodontal tissue were taken from periodontitis-affected patients and from healthy subjects. Immunohistochemistry was performed to count CD19(+) B cells, CD3(+) total T cells, T-CD4(+) and T-CD8(+) cell subsets, and PCR was performed to detect cytomegalovirus and human herpesvirus 6 and 7 in the samples. One slide of each sample was stained with Giemsa for histopathological examination and to evaluate the quality of the cellular infiltrate. RESULTS: As expected, tissues collected from healthy subjects presented no significant level of inflammatory infiltration and were therefore excluded from immunostaining procedures. Results showed that CD19(+) B cells were in higher number than CD3(+) T cells in the periodontitis-affected tissue, but this was not statistically significant. The T-CD4(+) lymphocyte subset was significantly higher than the T-CD8(+) lymphocyte subset (p = 0.004) in the samples. Cytomegalovirus and human herpesvirus 7 were found at periodontitis-affected sites, but not in tissue collected from healthy subjects (p = 0.04 and p = 0.04, respectively). Human herpesvirus 6 was rarely detected. We found a correlation between cytomegalovirus and lower CD19(+) /CD3(+) ratios (ratio < 0.9, p = 0.003) and between human herpesvirus 7 and lower CD19(+) /CD3(+) ratios (ratio < 0.9, p = 0.003) and higher CD4(+) /CD8(+) ratios (ratio > 1.1, p = 0.002). CONCLUSION: This study shows that cytomegalovirus and human herpesvirus 7 can be present at periodontitis-affected sites but are uncommon at healthy periodontal sites. Moreover, our data suggest that cytomegalovirus can be related to an inflammatory infiltrate with predominance of CD3(+) T cells, whereas human herpesvirus 7 can be associated with an infiltrate with predominance of T-CD4(+) cells. However, further studies are necessary to support this hypothesis. Herpesviruses could play a role in human chronic periodontitis by modulation of the T cell response.

Human herpesvirus 7 u21 downregulates classical and nonclassical class I major histocompatibility complex molecules from the cell surface.

Herpesviruses have evolved numerous strategies to evade detection by the immune system. Notably, most of the herpesviruses interfere with viral antigen presentation to cytotoxic T lymphocytes (CTLs) by removing class I major histocompatibility complex (MHC) molecules from the infected cell surface. Clearly, since the herpesviruses have evolved an extensive array of mechanisms to remove class I MHC molecules from the cell surface, this strategy serves them well. However, class I MHC molecules often serve as inhibitory ligands for NK cells, so viral downregulation of all class I MHC molecules should leave the infected cell open to NK cell attack. Some viruses solve this problem by selectively downregulating certain class I MHC products, leaving other class I products at the cell surface to serve as inhibitory NK cell ligands. Here, we show that human herpesvirus 7 (HHV-7) U21 binds to and downregulates all of the human class I MHC gene products, as well as the murine class I molecule H-2K(b). HHV-7-infected cells must therefore possess other means of escaping NK cell detection.

Cell Fusion and Syncytium Formation in Betaherpesvirus Infection.

Cell-cell fusion is a fundamental and complex process that occurs during reproduction, organ and tissue growth, cancer metastasis, immune response, and infection. All enveloped viruses express one or more proteins that drive the fusion of the viral envelope with cellular membranes. The same proteins can mediate the fusion of the plasma membranes of adjacent cells, leading to the formation of multinucleated syncytia. While cell-cell fusion triggered by alpha- and gammaherpesviruses is well-studied, much less is known about the fusogenic potential of betaherpesviruses such as human cytomegalovirus (HCMV) and human herpesviruses 6 and 7 (HHV-6 and HHV-7). These are slow-growing viruses that are highly prevalent in the human population and associated with several diseases, particularly in individuals with an immature or impaired immune system such as fetuses and transplant recipients. While HHV-6 and HHV-7 are strictly lymphotropic, HCMV infects a very broad range of cell types including epithelial, endothelial, mesenchymal, and myeloid cells. Syncytia have been observed occasionally for all three betaherpesviruses, both during in vitro and in vivo infection. Since cell-cell fusion may allow efficient spread to neighboring cells without exposure to neutralizing antibodies and other host immune factors, viral-induced syncytia may be important for viral dissemination, long-term persistence, and pathogenicity. In this review, we provide an overview of the viral and cellular factors and mechanisms identified so far in the process of cell-cell fusion induced by betaherpesviruses and discuss the possible consequences for cellular dysfunction and pathogenesis.

IgG subclasses and DNA detection of HHV-6 and HHV-7 in healthy individuals.

Human herpesvirus 6 (HHV-6) and 7 (HHV-7) are common opportunistic agents in immunocompromised hosts, although infection with HHV-6 and HHV-7 can also be observed in immunocompetent hosts. Despite similar biology and epidemiology, this study evaluated differences in the IgG subclass distribution associated with HHV-6 and HHV-7 in seropositive, healthy persons. The identified subclasses were also compared with the detection of HHV-6 and HHV-7 DNA. For these assays, sera, plasma, and saliva samples were obtained from 40 healthy blood donors in Argentina who were seropositive for both HHV-6 and HHV-7. HHV-6 and HHV-7 DNA were detected in saliva and plasma samples using nested PCR, and specific IgG subclasses were determined using immunofluorescent assays of sera samples. HHV-7 DNA was detected in 90% of all plasma samples and in 100% of saliva samples. In contrast, HHV-6 DNA was not detected in any of the plasma samples, and it was detected in only 6 of 40 saliva samples. Determination of IgG subclass distributions showed that HHV-6 was restricted to IgG1, whereas HHV-7 IgG subclasses included two groups, one restricted only to IgG1 and the other to IgG1 and IgG3. These results demonstrate the differences between HHV-6 and HHV-7 DNA range detection in saliva and plasma samples, as well as the IgG subclass patterns for each virus type, in healthy persons in Argentina.

Lymphoproliferative response to herpes simplex virus type 1, cytomegalovirus, Epstein-Barr virus, varicella zoster virus, human herpes virus 6, 7, and 8 antigen stimulation in pediatric allogeneic stem cell transplant recipients.

We evaluate the recovery of CMI to various herpes viruses by measuring in vitro LPR to specific recall antigens. CMI was evaluated by the in vitro LPR of PBMC to specific purified HSV-1, VZV, CMV, EBV, HHV-6, -7, -8, antigens. Results were expressed as SI. SI > or = 3 was regarded as positive LPR. Serial measurements were taken prospectively from pretransplant till 12-month post-transplant. Thirty-six patients (M = 19; F = 17) with median age 10.5 yr old were recruited. Most transplants were from MSD with PBSC as the stem cell source. Altogether 50% of subjects started to show positive LPR to HSV-1, CMV, and VZV antigens at two-month post-transplant, major upsurges were noted until 6-month post-transplant. Subjects showed positive LPR to EBV, HHV-6, HHV-7, and HHV-8 antigens were all along <50% throughout the study period. The antibody status of donor and recipient for HSV-1, CMV, and VZV were associated with the timing of recovery of CMI. Choice of donor and stem cell source were important determinants of eventual LPR to various herpes viruses at 3-month post-transplant. At 12-month post-transplant, there was no statistical difference in any parameters in affecting LPR to different herpes viruses.

Drug rash with eosinophilia and systemic symptoms (DRESS): changing carbamazepine to phenobarbital controlled epilepsy without the recurrence of DRESS.

We report a case of drug rash with eosinophilia and systemic symptoms (DRESS) due to carbamazepine. Anticonvulsants are the most common medicines causing DRESS and once it occurs, it is difficult to find an effective alternative treatment. In our case, switching from carbamazepine to phenobarbital successfully controlled both the DRESS and the convulsions. A positive patch test indicates the major role of delayed type allergy in the pathogenesis of this syndrome. Although reactivation of some viruses has been reported, their pathogenic role was not confirmed in our case.

[Human herpesvirus 7]. / Az emberi 7-es herpeszvírus.

Human herpesvirus 7 known since 1990 is closely related to herpesvirus 6B. It replicates in human cells only after binding CD4 receptor. It establishes lifelong latency in infected cells, and its frequent reactivations result in asymptomatic virus shedding through saliva. Most children acquire infection by age 3 and 4, but in any later age group seronegative individuals are at risk of infection. Rarely, exanthema subitum or convulsions with fever in children, pityriasis rosea in young adults, lethal complications in immunocompromised persons with concomitant herpesvirus 6B and cytomegalovirus reactivation occur. The most important pathogenic changes are due to the altered cytokine and growth factor secretion from infected lymphocytes with subsequent chain reaction on immune and other cells. Antiviral antibodies are detected by commercial kits (immunofluorescence, ELISA, immunoblot), nucleic acid by nested polymerase chain reaction. The majority of conditions due to infection do not require antiviral medication, but the severe complications are treated with ganciclovir and its derivates or foscarnet and cidofovir.

[Human herpesvirus-6 and human herpesvirus-7 (HHV-6, HHV-7)].

human herpesvirus 6 (HHV-6) is the major causative agent of exanthem subitum which is one of popular diseases in infant, and establishes latent infections in adults of more than 90%. Recently, the encephalitis caused by reactivated- HHV-6 has been shown in patients after transplantation. In addition, the relationship HHV-6 and drug-induced hypersensitivity syndrome has also been reported. human herpesvirus 7 (HHV-7) was isolated from the stimulated-peripheral blood lymphocytes of a healthy individual, and also causes exanthema subitum. Both viruses are related viruses which belong to betaherpesvirus subfamily, and replicate and produce progeny viruses in T cells.

Development of an enzyme-linked immunosorbent assay for diagnosis of human herpesvirus-7 infection.

INTRODUCTION: Human herpesvirus (HHV)-7 establishes a latent infection during the lifetime of the host and can reactivate after the primary infection, leading to lytic replication in immunosuppressed patients. METHODS: This study aimed to develop an enzyme-linked immunosorbent assay (ELISA) to identify HHV-7 serum antibodies and compare its performance with that of an indirect immunofluorescence assay (IFA). RESULTS: Serum samples (n=102) were tested by IgG-IFA and by ELISA. IFA and ELISA showed IgG-positive results in 77 and 73 samples, respectively. Qualitative concordance of 96% was demonstrated between the two techniques. CONCLUSIONS: ELISA may be useful to diagnose HHV-7 infection.

Identification of RANTES, MIP-1 alpha, and MIP-1 beta as the major HIV-suppressive factors produced by CD8+ T cells.

Evidence suggests that CD8+ T lymphocytes are involved in the control of human immunodeficiency virus (HIV) infection in vivo, either by cytolytic mechanisms or by the release of HIV-suppressive factors (HIV-SF). The chemokines RANTES, MIP-1 alpha, and MIP-1 beta were identified as the major HIV-SF produced by CD8+ T cells. Two active proteins purified from the culture supernatant of an immortalized CD8+ T cell clone revealed sequence identity with human RANTES and MIP-1 alpha. RANTES, MIP-1 alpha, and MIP-1 beta were released by both immortalized and primary CD8+ T cells. HIV-SF activity produced by these cells was completely blocked by a combination of neutralizing antibodies against RANTES, MIP-1 alpha, and MIP-1 beta. Recombinant human RANTES, MIP-1 alpha, and MIP-1 beta induced a dose-dependent inhibition of different strains of HIV-1, HIV-2, and simian immunodeficiency virus (SIV). These data may have relevance for the prevention and therapy of AIDS.

Human herpesvirus-7 in Brazilian liver transplant recipients: a follow-up comparison between molecular and immunological assays.

Human herpesvirus-6 and -7 (HHV-6, HHV-7) remain latent after primary infection and can reactivate after transplantation. HHV-6 active infection has been related to some clinical manifestation, but the role of HHV-7 remains unclear. The clinical significance of HHV-7 DNAemia is not completely known and the immune response against HHV-7 has been poorly studied in transplantation. In this study, we investigated HHV-7 DNAemia in liver transplant recipients and evaluated the immunoglobulin (Ig) G and IgM response against HHV-7. A total of 22 adult liver transplant recipients were followed up for 90 days. HHV-7 DNAemia was detected by nested polymerase chain reaction (PCR) in DNA extracted from sera. IgG and IgM detection was performed by immunofluorescent assay using HHV-7-infected cord blood mononuclear cells. A significant virus antibody response was defined as either a positive IgM or a > or =4-fold rise in the virus IgG antibody. All patients had pre-transplant HHV-7-positive serostatus. Nine of 22 (40.9%) patients presented HHV-7 DNAemia during follow-up. All these patients had anti-HHV-7-positive IgM and/or significant increase in IgG titers with concurrent or subsequent DNAemia. In patients without DNAemia and low persistent IgG antibody titers, IgM was not detected. Correlation between nested PCR and IgM detection was statistically significant (P=0.01). Our study indicates that nested PCR in DNA extraction from serum can be useful to detect and monitor HHV-7 active infection in liver transplant recipients. IgM antibody detection also can be useful as a first immunological technique to detect active infection, especially if combined with PCR.