High prevalence of HHV-6 DNA in peripheral blood mononuclear cells of healthy individuals detected by nested-PCR

Infection, Rejection, and the Connection

Solid organ transplantation is a life-saving treatment for people with end-stage organ disease. Immune-mediated transplant rejection is a common complication that decreases allograft survival. Although immunosuppression is required to prevent rejection, it also increases the risk of infection. Some infections, such as cytomegalovirus and BK virus, can promote inflammatory gene expression that can further tip the balance toward rejection. BK virus and other infections can induce damage that resembles the clinical pathology of rejection, and this complicates accurate diagnosis. Moreover, T cells specific for viral infection can lead to rejection through heterologous immunity to donor antigen directly mediated by antiviral cells. Thus, viral infections and allograft rejection interact in multiple ways that are important to maintain immunologic homeostasis in solid organ transplant recipients. Better insight into this dynamic interplay will help promote long-term transplant survival.

Disruption of thymic central tolerance by infection with murine roseolovirus induces autoimmune gastritis

Infections with herpesviruses, including human roseoloviruses, have been proposed to cause autoimmune disease, but defining a causal relationship and mechanism has been difficult due to the ubiquitous nature of infection and development of autoimmunity long after acute infection. Murine roseolovirus (MRV) is highly related to human roseoloviruses. Herein we show that neonatal MRV infection induced autoimmune gastritis (AIG) in adult mice in the absence of ongoing infection. MRV-induced AIG was dependent on replication during the neonatal period and was CD4+ T cell and IL-17 dependent. Moreover, neonatal MRV infection was associated with development of a wide array of autoantibodies in adult mice. Finally, neonatal MRV infection reduced medullary thymic epithelial cell numbers, thymic dendritic cell numbers, and thymic expression of AIRE and tissue-restricted antigens, in addition to increasing thymocyte apoptosis at the stage of negative selection. These findings strongly suggest that infection with a roseolovirus early in life results in disruption of central tolerance and development of autoimmune disease.

The Spontaneous Course of Human Herpesvirus 6 DNA-Associated Myocarditis and the Effect of Immunosuppressive Intervention

Introduction: This study investigated the spontaneous clinical course of patients with endomyocardial biopsy (EMB)-proven lymphocytic myocarditis and cardiac human herpesvirus 6 (HHV6) DNA presence, and the effectiveness of steroid-based intervention in HHV6-positive patients. Results: 756 heart failure (HF) patients underwent an EMB procedure to determine the underlying cause of unexplained HF. Low levels of HHV6 DNA, detectable by nested PCR only, were found in 10.4% of the cases (n = 79) of which 62% (n = 49) showed myocardial inflammation. The spontaneous course of patients with EMB-proven HHV6 DNA-associated lymphocytic myocarditis (n = 26) showed significant improvements in the left ventricular ejection fraction (LVEF) and clinical symptoms, respectively, in 15/26 (60%) patients, 3–12 months after disease onset. EMB mRNA expression of components of the NLRP3 inflammasome pathway and protein analysis of cardiac remodeling markers, analyzed by real-time PCR and MALDI mass spectrometry, respectively, did not differ between HHV6-positive and -negative patients. In another cohort of patients with ongoing symptoms related to lymphocytic myocarditis associated with cardiac levels of HHV6-DNA copy numbers <500 copies/µg cardiac DNA, quantified by real-time PCR, the efficacy and safety of steroid-based immunosuppression for six months was investigated. Steroid-based immunosuppression improved the LVEF (≥5%) in 8/10 patients and reduced cardiac inflammation in 7/10 patients, without an increase in cardiac HHV6 DNA levels in follow-up EMBs. Conclusion: Low HHV6 DNA levels are frequently detected in the myocardium, independent of inflammation. In patients with lymphocytic myocarditis with low levels of HHV6 DNA, the spontaneous clinical improvement is nearby 60%. In selected symptomatic patients with cardiac HHV6 DNA copy numbers less than 500 copies/µg cardiac DNA and without signs of an active systemic HHV6 infection, steroid-based therapy was found to be effective and safe. This finding needs to be further confirmed in large, randomized trials.

Murine roseolovirus does not accelerate amyloid-β pathology and human roseoloviruses are not over-represented in Alzheimer disease brains

BACKGROUND

The role of viral infection in Alzheimer Disease (AD) pathogenesis is an area of great interest in recent years. Several studies have suggested an association between the human roseoloviruses, HHV-6 and HHV-7, and AD. Amyloid-β (Aβ) plaques are a hallmark neuropathological finding of AD and were recently proposed to have an antimicrobial function in response to infection. Identifying a causative and mechanistic role of human roseoloviruses in AD has been confounded by limitations in performing in vivo studies. Recent -omics based approaches have demonstrated conflicting associations between human roseoloviruses and AD. Murine roseolovirus (MRV) is a natural murine pathogen that is highly-related to the human roseoloviruses, providing an opportunity to perform well-controlled studies of the impact of roseolovirus on Aβ deposition.

METHODS

We utilized the 5XFAD mouse model to test whether MRV induces Aβ deposition in vivo. We also evaluated viral load and neuropathogenesis of MRV infection. To evaluate Aβ interaction with MRV, we performed electron microscopy. RNA-sequencing of a cohort of AD brains compared to control was used to investigate the association between human roseolovirus and AD.

RESULTS

We found that 5XFAD mice were susceptible to MRV infection and developed neuroinflammation. Moreover, we demonstrated that Aβ interacts with viral particles in vitro and, subsequent to this interaction, can disrupt infection. Despite this, neither peripheral nor brain infection with MRV increased or accelerated Aβ plaque formation. Moreover, -omics based approaches have demonstrated conflicting associations between human roseoloviruses and AD. Our RNA-sequencing analysis of a cohort of AD brains compared to controls did not show an association between roseolovirus infection and AD.

CONCLUSION

Although MRV does infect the brain and cause transient neuroinflammation, our data do not support a role for murine or human roseoloviruses in the development of Aβ plaque formation and AD.

Human herpesvirus 6A active infection in patients with autoimmune Hashimoto's thyroiditis

BACKGROUND

Hypothyroidism due to Hashimoto's thyroiditis (HT) is the commonest autoimmune endocrine illness in which antibodies against thyroid organ result in inflammation. The disease has a complex etiology that involves genetic and environmental influences. Viral infections may be involved in triggering of the disease as their molecular mimicry enhance autoimmune responses. Human herpesvirus-6 (HHV-6) is recognized for its contribution to some autoimmune diseases.

OBJECTIVE

In the current study, the prevalence of HHV-6 active infection in patients with HT and with non-autoimmune thyroid disorders were compared with patients with euthyroidism. In addition, a correlation between presence of HHV-6 infections and HT was investigated.

METHODS

A total of 151 patients with clinically and laboratory confirmed HT, 59 patients with non-autoimmune thyroid disorders, and 32 patients with normal thyroid function were included in the study. For further confirmation of HT disease, all the precipitants were tested for anti-thyroid peroxidase (TPO), and anti-thyroglobulin (TG) antibodies. For detection of both HHV-6 types A and B, nested PCR and restriction enzyme digestion were used. HHV-6 DNA positive samples were further investigated by DNA sequencing analysis.

RESULTS

HHV-6A DNA was found in serum sample of 57 out of 151 patients (38%) with HT, which was significantly more often than in patients with non-autoimmune thyroid disorders (p=0.001). However, HHV-6 DNA was not detected in serum samples of euthyroid subjects.

CONCLUSIONS

The results support a possible role for active HHV-6A infection, demonstrated by the presence of HHV-6 DNA in sera, in the development of HT.

Human Herpes Virus 6 (HHV-6)-associated Lymphadenitis: Pitfalls in Diagnosis in Benign and Malignant Settings

Human herpes virus 6 (HHV-6) is a member of the β-herpesvirinae subfamily. Most people acquire HHV-6 primary infection early in life and reactivation may occur, most often in immunocompromised individuals, leading to various clinical manifestations. HHV-6 infected cells may be identified in lymph nodes in both reactive and neoplastic conditions. Cases were retrieved from the hematopathology consultation service archives at National Institutes of Health from 2003 to 2017 in which infection by HHV-6 had been documented by immunohistochemical stains to HHV-6 gp60/110 envelope glycoprotein. Five cases of reactive lymphadenitis and 3 cases of lymphoma; 2 angioimmunoblastic T-cell lymphoma and 1 classic Hodgkin lymphoma, positive for HHV-6 were identified. The reactive lymph nodes showed marked paracortical hyperplasia and admixed large atypical lymphoid cells exhibiting pleomorphic nuclei, vesicular chromatin, and prominent eosinophilic intranuclear inclusions. Vascular proliferation and necrosis were also present, raising suspicion of peripheral T-cell lymphoma. The 3 cases of lymphoma showed similar viral inclusions, in addition to the characteristic features diagnostic of the lymphoma. Staining for HHV-6 was positive with a membranous and Golgi pattern and was restricted to cells with evident inclusions on hematoxylin and eosin. HHV-6 infected cells were positive for CD3 and CD4. HHV-6 lymphadenitis can present with morphologic atypia creating a diagnostic pitfall for lymphoma. In such cases, careful attention to the characteristic viral inclusions can lead to immunohistochemical analysis highlighting the replicating virus. In cases of lymphoma, identification of the inclusions is key in detecting the associated infection as well as in avoiding misinterpretation of the lymphoma subtype.

Coinfection of human herpesviruses 6A (HHV-6A) and HHV-6B as demonstrated by novel digital droplet PCR assay

The human herpesviruses HHV-6A and HHV-6B have been associated with various neurologic disorders partly due to the detection of elevated viral DNA levels in patients compared to controls. However the reported frequency of these viruses varies widely, likely reflecting differences in PCR methodologies used for detection. Digital droplet PCR (ddPCR) is a third generation PCR technology that enables the absolute quantification of target DNA molecules. Mounting evidence of the biological differences between HHV-6A and HHV-6B has led to their recent reclassification as separate species. As it is now especially relevant to investigate each virus, our objectives were to first design a multiplex HHV-6A and HHV-6B ddPCR assay and then to investigate the incidence of HHV-6A and HHV-6B coinfection in samples from healthy donors and patients with MS, a disease in which HHV-6 is thought to play a role. In our assessment of healthy donors, we observed a heretofore-underappreciated high frequency of coinfection in PBMC and serum, and found that our assay precisely detects both HHV-6A and HHV-6B chromosomally integrated virus, which has important implications in clinical settings. Interestingly, upon comparing the saliva from MS patients and healthy donors, we detected a significantly elevated frequency of coinfection in MS saliva; increased detection of HHV-6A in MS patients is consistent with other studies suggesting that this viral species (thought to be more neurotropic than HHV-6B) is more prevalent among MS patients compared to healthy donors. As the biology and disease associations between these two viral species differ, identifying and quantifying both species of HHV-6 may provide clinically relevant information, as well as enhance our understanding of the roles of each in health and disease.

Virus specific cell-mediated immunity may play a role in controlling reactivated human herpesvirus 6B in patients under measles induced immunosuppression

For a better understanding of the cellular immune responses to reactivated HHV 6B the lymphoproliferative response to human herpesvirus 6B (HHV 6B) antigen was measured in three consecutive specimens obtained biweekly from 22 young children and infants suffering from acute measles, and in 19 influenza patients and nine healthy control subjects. HHV 6B DNA in peripheral blood mononuclear cells (PBMCs) was detected in 18 of 22 subjects with measles, but not in the influenza patients or the healthy population. A novel reactivation profile of HHV 6B was found in patients with measles in the milder form of immunosuppression than in patients with organ transplantation. HHV 6B specific lymphoproliferation activities increased correspondingly with reactivation of HHV 6B assessed by detecting HHV 6B DNA in PBMCs in patients with measles, but no significant change in either the antibody response to HHV 6B or DNAemia occurred in serial specimens obtained either from patients with influenza or healthy subjects. This novel form of HHV 6B reactivation without antibody response was observed in patients with measles. The dynamic fluctuations in lymphoproliferative responses in measles may represent the balance between HHV 6B reactivation and its suppression by the host immune system.

Chlamydia trachomatis infection induces replication of latent HHV-6

Human herpesvirus-6 (HHV-6) exists in latent form either as a nuclear episome or integrated into human chromosomes in more than 90% of healthy individuals without causing clinical symptoms. Immunosuppression and stress conditions can reactivate HHV-6 replication, associated with clinical complications and even death. We have previously shown that co-infection of Chlamydia trachomatis and HHV-6 promotes chlamydial persistence and increases viral uptake in an in vitro cell culture model. Here we investigated C. trachomatis-induced HHV-6 activation in cell lines and fresh blood samples from patients having Chromosomally integrated HHV-6 (CiHHV-6). We observed activation of latent HHV-6 DNA replication in CiHHV-6 cell lines and fresh blood cells without formation of viral particles. Interestingly, we detected HHV-6 DNA in blood as well as cervical swabs from C. trachomatis-infected women. Low virus titers correlated with high C. trachomatis load and vice versa, demonstrating a potentially significant interaction of these pathogens in blood cells and in the cervix of infected patients. Our data suggest a thus far underestimated interference of HHV-6 and C. trachomatis with a likely impact on the disease outcome as consequence of co-infection.

Pityriasis rosea: an update with a critical appraisal of its possible herpesviral etiology

Pityriasis rosea is an acute, self-healing exanthem characterized by oval erythematous-squamous lesions of the trunk and limbs, that usually spares face, scalp, palms, and soles. Constitutional symptoms, which have the character of true prodromes; clinical features, which resemble those of the known exanthems; and many epidemiologic data all suggest an infectious origin. A host of infectious agents have been incriminated, but, recently, human herpesvirus 6 and 7 have been extensively studied. The goal of this review is to outline the epidemiologic, clinical, histologic, and ultrastructural features of pityriasis rosea, but mainly to stress its possible human herpesvirus nature. In addition, clues have been added to help the reader to go through the complex subtleties of the virologic investigation.

Herpesvirus prevalence and viral load in healthy blood donors by quantitative real-time polymerase chain reaction

BACKGROUND

After primary infection, human herpesviruses (HHVs) maintain long-term latent persistence, often punctuated years later by sporadic episodes of symptomatic lytic activation. Also, blood-borne herpesvirus from healthy persistently infected blood donors can lead to active primary infection of immunocompromised transfusion recipients.

STUDY DESIGN AND METHODS

Utilizing a set of newly developed real-time polymerase chain reaction assays for detection and quantification of all eight human herpesviruses, the prevalence and viral DNA load of white cell-enriched blood from 100 randomly selected blood donors from the southeast Texas region are reported.

RESULTS

Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), and HHV-8 DNA were not detected in any donor sample. In contrast, Epstein-Barr virus (EBV) (72%) and HHV-7 (65%) were commonly detected, HHV-6 (30%) was often detected (Type B only), and cytomegalovirus (CMV; 1%) was rarely detected. Median viral loads of positive samples (per milliliter of blood) ranged from 4278 for HHV-6 to less than 46 for EBV.

CONCLUSIONS

These results suggest that the potential for transfusion-mediated transmission of herpesviruses from healthy adult blood donors is high for EBV and HHV-7; moderately high for HHV-6; uncommon for CMV; and rare for HSV-1, HSV-2, VZV, and HHV-8. Perhaps the most remarkable finding in this study was the detection of a single donor sample with greater than 6.1 x 10(7) HHV-6 Type B genome equivalents per mL blood. Given that this extraordinarily high level of HHV-6 DNA was obtained from a healthy adult blood donor, this phenomenon is likely unrelated to active infection or immunodeficiency.

Differential HHV-6A gene expression in T cells and primary human astrocytes based on multi-virus array analysis

Human herpesvirus 6 (HHV-6) is a ubiquitous virus that has been associated with a wide spectrum of diseases, such as exanthem infantum, multiple sclerosis, seizures, encephalitis/meningitis, and more recently, mesial temporal lobe sclerosis. Although HHV-6 is known to predominately infect CD4+ T lymphocytes, its ability to infect neural glial cells has been demonstrated both in vitro and in vivo. Reactivation of latent HHV-6 infection in the brain has recently been suggested to play a role in the development of neuropathogenesis. To investigate the association of viral gene expression and disease pathogenesis, we developed a multi-virus array containing all open reading frames of the HHV-6 virus and other pathogenically related viruses (EBV, HBV, HHV-8, HIV-1, HTLV-1, HTLV-2) to study expression of viral gene transcripts. In this study, we infected CD4+ T lymphocytes and primary human astrocytes derived from brain biopsy material in vitro with the more neurotropic HHV-6A strain. Hierarchal cluster analysis based on gene expression over time suggested a temporally regulated herpesvirus transcription process. Furthermore, we compared viral gene expression in CD4+ T lymphocytes and primary human astrocytes at peak viral load levels (>10(8) copies of virus/10(6) cells) at 5 days post-infection. Differential expression of HHV-6A genes was observed between CD4+ T lymphocytes and primary human astrocytes. Absence of a number of HHV-6 genes detected at 5 days post-infection in primary human astrocytes suggests an alternative replication strategy used by HHV-6 to evade immune detection and allow establishment of persistent infection in neural glial cells.

The Effect of Valacyclovir Treatment on Natural Killer Cells of Infertile Women

PROBLEM

The aim of this study was to investigate the effect of valacyclovir treatment on natural killer (NK) cell concentration in the peripheral blood of infertile women.

METHOD OF STUDY

Peripheral blood NK cell concentration of 104 non-pregnant women with a history of infertility was determined by flow cytometry. The controls were 14 fertile non-pregnant women. A cohort of 42 out of 104 women--whose NK cell levels were 175/microL or higher--was prospectively studied for the presence of HSV-1, 2, VZV, cytomegalovirus, HHV-6, HHV-7 and HHV-8 DNA in the peripheral blood and was orally administered valacyclovir (open label study).

RESULTS

Herpes virus DNA was detected in 64.3% of the 42 women examined. Prior to valacyclovir treatment mean NK cell concentration in herpes-negative group was statistically higher from control group but lower from herpes positive group (P = 0.0007, ANOVA). Following valacyclovir treatment the mean NK cell concentration was statistically decreased in all studied women (P = 0.000453), in herpes-negative (P = 0.01622) and in herpes positive group (P = 0.0056). Sufficient decrease was observed in 31 (73.8%) of 42 women who received the drug.

CONCLUSIONS

Valacyclovir treatment is associated with a decrease of NK cell levels in most of the women with a history of infertility.

Mathematical model to simulate the cellular dynamics of infection with human herpesvirus-6 in EBV-negative infectious mononucleosis

Acute infection with human herpesvirus-6 induces physiological cell proliferation in persons without major immune deficiency. It thus can serve as a parameter to validate a mathematical model designed to simulate cell proliferation under physiological and pathological conditions. Such a mathematical model is presented to simulate various cell changes of the T-cell immune system during the course of HHV-6 infection. Model development follows several steps, beginning with a basic model containing physiological T-cell pools to the introduction of infectious stimuli in the final model. A search algorithm designed to optimize the system parameters, as well as initial variables of the model, is presented. The results of simulation runs for acute HHV-6 infection of the final computational model correspond well to the data, as documented in human patients; they suggest that the computational model presented for the simulation of T-cell levels in a given viral infection may well serve as a tool for similar studies of other viral infections, including those that lead to cellular aplasia or neoplasia.

Human herpesvirus-6 modulates RANTES production in primary human endothelial cell cultures

Human herpesvirus 6 (HHV6) is a beta-herpesvirus capable of infecting several cell types from different origins. HHV6 is the etiological agent of exantem subitum and has been associated with several diseases, all characterized by an inflammatory response triggered by chemokines. We show that strain U1102 of HHV6 is able to infect persistently human endothelial cells obtained from umbilical veins, adult aorta and adult heart microvessels, without apparent cytopathic effect. Analysis by in situ PCR showed that HHV6 sequences were present in 20% of HUVEC, 10% of aortic, and 1% of heart microvascular endothelial cells. Regardless of endothelial cell origin, HHV6 infection induced de novo synthesis of the RANTES CC-chemokine. It was found, however, that microvascular endothelial cells, despite their lower susceptibility to HHV6 infection, showed the highest RANTES expression. Chemokine production occurred also in the absence of viral DNA synthesis. Furthermore, RANTES synthesis required an active viral genome, as UV-inactivated HHV6 infection of endothelial cells did not lead to chemokine production. We investigated the expression of HHV6 U51 gene, which encodes a chemokine receptor that is already known to sequester and down modulate RANTES in epithelial cells. HHV6-infected endothelial cells co-expressed RANTES and U51 mRNAs starting from 12 hr up to 48 hr post-infection. Then, RANTES transcripts disappeared whereas U51 messages continued to be expressed. In conclusion, this study highlights the major role of HHV6 in endothelial cell biology and the development of inflammatory processes.

Markers of viral infection in monozygotic twins discordant for chronic fatigue syndrome

To estimate the prevalence of viruses associated with chronic fatigue syndrome (CFS) and to control for genetic and environmental factors, we conducted a co-twin control study of 22 monozygotic twin pairs, of which one twin met criteria for CFS and the other twin was healthy. Levels of antibodies to human herpesvirus (HHV)-8, cytomegalovirus, herpes simplex virus 1 and 2, and hepatitis C virus were measured. Polymerase chain reaction (PCR) assays for viral DNA were performed on peripheral blood mononuclear cell specimens to detect infection with HHV-6, HHV-7, HHV-8, cytomegalovirus, Epstein-Barr virus, herpes simplex virus, varicella zoster virus, JC virus, BK virus, and parvovirus B19. To detect lytic infection, plasma was tested by PCR for HHV-6, HHV-8, cytomegalovirus, and Epstein-Barr virus DNA, and saliva was examined for HHV-8 DNA. For all assays, results did not differ between the group of twins with CFS and the healthy twins.

A mu-capture immunoassay for detection of human herpes virus-6 (HHV-6) IgM antibodies in human serum

BACKGROUND

Human herpes virus-6 (HHV-6) was first isolated in 1986. It has been shown to cause exanthema subitum and has been associated with various other diseases. HHV-6 infection is widespread, and more than 90% of the population have antibodies against HHV-6 at the age of 2 years. Once acquired, the virus remains latent in the body. This makes it difficult to draw any conclusions about a causal relationship between the demonstration of HHV-6 and a specific disease.

OBJECTIVES

This work was to develop a mu-capture HHV-6 IgM enzyme linked immuno sorbent assay (ELISA) for use in routine diagnosis and for wide scale patient population analysis.

STUDY DESIGN

A mu-capture HHV-6 IgM ELISA was established. A total of 682 sera consisting of 585 sera from Danish blood donors and 97 sera from patients with autoimmune antibodies were analysed in the HHV-6 IGM ELISA. One hundred and ninety-two sera had earlier been analysed for total HHV-6 antibody content in a competitive ELISA, 94 sera were analysed for cytomegalovirus (CMV) IgM and 57 sera for Epstein Barr virus (EBV) antibodies, using different ELISA assays. The results for 12 primary infections with HHV-6 are also reported.

RESULTS

A HHV-6 IgM optical density (OD)-ratio was calculated according to a constant positive control. An empirical cut off of 0.5 HHV-6 IgM OD-ratio was chosen (with regard to the 10 HHV-6 seroconverters), which resulted in a specificity of 97.5% of the HHV-6 IgM ELISA. Two of the three donor sera with HHV-6 IgM OD-ratios more than 1.05 had total HHV-6 antibody titers significantly above the group with IgM OD-ratios below 0.7 consisting with HHV-6 reactivation. There was no cross reactions to EBV or CMV IgM positive sera.

CONCLUSION

The HHV-6 IgM ELISA seems valid to diagnose primary HHV-6 infection in particular in combination with the HHV-6 total antibody assay.

Herpesviruses in HIV-periodontitis

BACKGROUND/AIMS

Human herpesvirus-associated diseases exhibit elevated morbidity and mortality in patients infected with human immunodeficiency virus (HIV). This study aimed to investigate the occurrence of herpesviruses in HIV-periodontitis.

METHOD

Gingival biopsies from periodontitis lesions of 21 HIV-patients and 14 non HIV-patients were studied. Nested-polymerase chain reaction methods were employed to detect human cytomegalovirus, Epstein-Barr virus type 1 and 2 (EBV-1, EBV-2), herpes simplex virus, human herpes virus (HHV)-6, HHV-7 and HHV-8.

RESULTS

Gingival biopsies from HIV-periodontitis lesions showed on average 4.0 herpesvirus species and gingival biopsies from HIV periodontitis lesions of non-HIV patients revealed an average of 1.9 herpesvirus species (p<0.001). Occurrence of 4 to 6 different herpesviruses was more common in HIV- than in non HIV-gingival biopsies (71% vs. 7%) (p<0.001). EVB-2 was detected in 12 (57%) biopsies from HIV-periodontitis but was absent in non HIV-periodontitis biopsies (p= 0.002). HHV-6 also occurred in significantly higher frequency in HIV-periodontitis (71%) than in non HIV-periodontitis (21%) (p=0.01). HHV-8 was detected only in biopsies from HIV-periodontitis lesions..

CONCLUSION

HIV-periodontitis seems to be associated with elevated occurrence of EBV-2, HHV-6 and herpesvirus co-infections compared to periodontitis in non-HIV-patients. The periodontopathic significance of herpesviruses in HIV-periodontitis constitutes a research topic of considerable interest.

Predictive value of quantitative PCR-based viral burden analysis for eight human herpesviruses in pediatric solid organ transplant patients

Human herpesviruses can cause significant morbidity and mortality in pediatric solid organ transplant recipients. It was hypothesized that viral burden quantification by polymerase chain reaction using an internal calibration standard could aid in distinguishing between viral disease and latency. Here we report the results of a 2-year prospective study of 27 pediatric solid organ (liver, kidney, or heart) transplant recipients in which multiple samples were analyzed for levels of all eight human herpesviruses by internal calibration standard-polymerase chain reaction. Herpes simplex viruses 1 and 2, varicella-zoster virus, and Kaposi's sarcoma-associated herpesvirus were not detected in any of these samples. Human herpesvirus types 6 and 7 were detected in half of the patients, but were present at low levels, similar to those found in reference populations. Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were detected in 89% and 56% of the patients, respectively. Viral burden analysis suggested distinct patient populations for CMV, with a natural cutoff of 10,000 viral targets/ml blood strongly associated with disease. In some cases, a dramatic increase in CMV levels preceded clinical evidence of disease by several weeks. EBV viral burden was relatively high in the only patient presenting with an EBV syndrome. However, two other patients without evidence of EBV disease had single samples with high EBV burden. Rapid reduction in both EBV and CMV burden occurred with antiviral treatment. These data suggest that viral burden analysis using internal calibration standard-polymerase chain reaction for CMV, and possibly other herpesviruses, is an effective method for monitoring pediatric transplant patients for significant herpesvirus infection and response to therapy.

The predictive value of uvulo-palatoglossal junctional ulcers as an early clinical sign of exanthem subitum due to human herpesvirus 6

BACKGROUND

The clinical sign of uvulo-palatoglossal junctional (UPJ) ulcers was first noted in 1983 in a 5.5-month-old baby with exanthem subitum (ES). An earlier prospective clinical study showed that there was a strong association of UPJ ulcers and occurrence of ES with a positive predictive value of 95.3% and negative predictive value of 100%.

OBJECTIVE

To determine the value of uvulo-palatoglossal junctional (UPJ) ulcers as an early clinical sign of exanthem subitum (ES) due to human herpesvirus 6 (HHV 6) infection.

STUDY DESIGN

A case-control study of 20 febrile children with UPJ ulcers versus 26 febrile children without UPJ ulcers. These children were followed up for any development of ES and investigated for human herpesvirus 6 (HHV 6) as the causative agents of the febrile episodes.

RESULTS

In this study, 20 out of 46 febrile children aged 3 months to 3 years with UPJ ulcers were virologically and/or serologically confirmed to be due to primary HHV 6 infection. The rest of the 26 children without ulcers did not have HHV 6 infection. Of the 20 children with UPJ ulcers, only 17 of the 19 children with adequate follow-up till subsidence of fever developed ES. None of the 26 children without UPJ ulcers developed ES.

CONCLUSION

Statistically, there was a significant association of UPJ ulcers as an early sign of ES with a positive predictive value of 89.5% and negative predictive value of 100%. This finding also suggests that the presence of UPJ ulcers is a useful pathognomic clinical sign of symptomatic primary HHV 6 infection.

Inheritance of Chromosomally Integrated Human Herpesvirus 6 DNA

Human herpesvirus 6 (HHV-6) genome has been detected in several human lymphoproliferative disorders with no signs of active viral infection, and found to be integrated into chromosomes in some cases. We previously reported a woman with HHV-6–infected Burkitt’s lymphoma. Fluorescence in situ hybridization showed that the viral genome was integrated into the long arm of chromosome 22 (22q13). The patient’s asymptomatic husband also carried HHV-6 DNA integrated at chromosome locus 1q44. To assess the possibility of chromosomal transmission of HHV-6 DNA, we looked for HHV-6 DNA in the peripheral blood of their daughter. She had HHV-6 DNA on both chromosomes 22q13 and 1q44, identical to the site of viral integration of her mother and father, respectively. The findings suggested that her viral genomes were inherited chromosomally from both parents. The 3 family members were all seropositive for HHV-6, but showed no serological signs of active infection. To confirm the presence of HHV-6 DNA sequences, we performed polymerase chain reaction (PCR) with 7 distinct primer pairs that target different regions of HHV-6. The viral sequences were consistently detected by single-step PCR in all 3 family members. We propose a novel latent form for HHV-6, in which integrated viral genome can be chromosomally transmitted. The possible role of the chromosomally integrated HHV-6 in the pathogenesis of lymphoproliferative diseases remains to be explained.

Inheritance of Chromosomally Integrated Human Herpesvirus 6 DNA

Human herpesvirus 6 (HHV-6) genome has been detected in several human lymphoproliferative disorders with no signs of active viral infection, and found to be integrated into chromosomes in some cases. We previously reported a woman with HHV-6–infected Burkitt’s lymphoma. Fluorescence in situ hybridization showed that the viral genome was integrated into the long arm of chromosome 22 (22q13). The patient’s asymptomatic husband also carried HHV-6 DNA integrated at chromosome locus 1q44. To assess the possibility of chromosomal transmission of HHV-6 DNA, we looked for HHV-6 DNA in the peripheral blood of their daughter. She had HHV-6 DNA on both chromosomes 22q13 and 1q44, identical to the site of viral integration of her mother and father, respectively. The findings suggested that her viral genomes were inherited chromosomally from both parents. The 3 family members were all seropositive for HHV-6, but showed no serological signs of active infection. To confirm the presence of HHV-6 DNA sequences, we performed polymerase chain reaction (PCR) with 7 distinct primer pairs that target different regions of HHV-6. The viral sequences were consistently detected by single-step PCR in all 3 family members. We propose a novel latent form for HHV-6, in which integrated viral genome can be chromosomally transmitted. The possible role of the chromosomally integrated HHV-6 in the pathogenesis of lymphoproliferative diseases remains to be explained.

U94 of human herpesvirus 6 is expressed in latently infected peripheral blood mononuclear cells and blocks viral gene expression in transformed lymphocytes in culture

Human herpesvirus 6 (HHV-6) like other herpesviruses, expresses sequentially immediate early (IE), early, and late genes during lytic infection. Evidence of ability to establish latent infection has not been available, but by analogy with other herpesviruses it could be expected that IE genes that regulate and transactivate late genes would not be expressed. We report that peripheral blood mononuclear cells of healthy individuals infected with HHV-6 express the U94 gene, transcribed under IE conditions. Transcription of other IE genes (U16/17, U39, U42, U81, U89/90, U91) was not detected. To verify that U94 may play a role in the maintenance of the latent state, we derived lymphoid cell lines that stably expressed U94. HHV-6 was able to infect these cells, but viral replication was restricted. No cytopathic effect developed. Furthermore, viral transcripts were present in the first days postinfection and declined thereafter. A similar decline in the level of intracellular viral DNA also was observed. These findings are consistent with the hypothesis that the U94 gene product of HHV-6 regulates viral gene expression and enables the establishment and/or maintenance of latent infection in lymphoid cells.

Development of a dot blot neutralizing assay for HHV-6 and HHV-7 using specific monoclonal antibodies

To elucidate further immune responses to human herpesviruses 6 and 7 (HHV-6 and -7), a neutralizing antibody assay was established for these viruses using a dot blot method. Three monoclonal antibodies against HHV-6 and 12 monoclonal antibodies against HHV-7 were developed and characterized by radio-immunoprecipitation. One monoclonal antibody which recognizes the 135 kDa late polypeptide of HHV-6 and several which recognize the 125 kDa late polypeptide of HHV-7 were selected to monitor virus growth by a dot blot antigen-detection method. The dot blot method was then used for the assay of HHV-6 and -7 neutralizing antibodies in human serum samples. The neutralization endpoints determined by the dot blot were comparable to those determined by immunofluorescence (IF). The neutralizing antibody titers appeared to correlate with the antibody titers determined by the indirect IF antibody test. The dot blot neutralization assay is easy to perform, is highly reproducible and objective when compared with the conventional methods based on cytopathology or IF for determining neutralization endpoints.

Identification of mimicry peptides based on sequential motifs of epitopes derived from 65-kDa glutamic acid decarboxylase

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease with a predominantly non-hereditary etiology that results in a destruction of pancreatic beta cells by autoaggressive T lymphocytes. Neither the mechanism of initial stimulation of these T cells nor the nature of the environmental factors implicated in the disease have so far been identified. However, both issues are taken into account by the hypothesis of initial T cell activation by viral or bacterial mimicry peptides with sequence similarities to pancreatic self antigens. We determined sequential epitope motifs to search for mimicry peptides stimulating T cell lines specific for two epitopes derived from the IDDM autoantigen 65-kDa glutamic acid decarboxylase (GAD65). These were GAD65 (88-99), presented by HLA-DRB1*0101, and GAD65 (248-257), presented by HLA-DRB5*0101. T cell stimulation by peptides with substitutions in HLA anchor or T cell contact positions was analyzed to establish degenerate epitope motifs for database searching. Out of 28 tested candidate mimicry peptides derived from bacterial, viral and human proteins, 3 stimulated T cell lines and a T cell clone specific for epitope GAD65 (248-257). Our results demonstrate that mono- and polyclonal GAD65-specific T cells from IDDM patients can be stimulated by viral and bacterial peptides with little apparent sequence homology with autoantigenic epitopes. Moreover, in a synopsis with related published studies, our findings suggest that simple degenerate search motifs comprising principal T cell contacts plus HLA class II binding motifs may suffice to identify most mimicry peptides.

Detection of human herpesvirus 6 DNA in serum by a microplate PCR-hybridization assay

PCR was performed on DNA extracts derived from clinical serum samples submitted for human herpesvirus 6 (HHV-6) serological examination. To detect amplified HHV-6 products, a hybridization-based microtiter plate assay (PCR ELISA; Boehringer Mannheim) was used. The assay system was found to be rapid, specific, and sensitive. Approximately three copies of a plasmid-based HHV-6 sequence could be detected, and no cross amplification was observed with HHV-7 genomic DNA. There was no correlation found between HHV-6 DNA detection and serological status in clinical serum samples from individuals more than 2 years old. On the other hand, in serum samples from infants less than 2 years old, a high rate of detection of HHV-6 DNA was observed in those who lacked immunoglobulin G and M antibodies to HHV-6 (55%). In this regard, PCR of serum DNA extracts may be used as a sensitive indicator of active HHV-6 infection in infants prior to their seroconversion.

Human herpesvirus 6

Human herpesvirus 6 variant A (HHV-6A) and human herpesvirus 6 variant B (HHV-6B) are two closely related yet distinct viruses. These visuses belong to the Roseolovirus genus of the betaherpesvirus subfamily; they are most closely related to human herpesvirus 7 and then to human cytomegalovirus. Over 95% of people older than 2 years of age are seropositive for either or both HHV-6 variants, and current serologic methods are incapable of discriminating infection with one variant from infection with the other. HHV-6A has not been etiologically linked to any human disease, but such an association will probably be found soon. HHV-6B is the etiologic agent of the common childhood illness exanthem subitum (roseola infantum or sixth disease) and related febrile illnesses. These viruses are frequently active and associated with illness in immunocompromised patients and may play a role in the etiology of Hodgkin's disease and other malignancies. HHV-6 is a commensal inhabitant of brains; various neurologic manifestations, including convulsions and encephalitis, can occur during primary HHV-6 infection or in immunocompromised patients. HHV-6 and distribution in the central nervous system are altered in patients with multiple sclerosis; the significance of this is under investigation.

Presence of human herpesvirus 6 variants A and B in saliva and peripheral blood mononuclear cells of healthy adults

Saliva and peripheral blood mononuclear cells (PBMCs) from 44 healthy young adults were tested for human herpesvirus 6 variants A and B (HHV-6A and -6B) DNA by a sensitive nested PCR. HHV-6B infection was ascertained in 98% of the subjects, and 95% were found to excrete variant B in their saliva. HHV-6A was found in the PBMCs of 16%, but was not detected in saliva samples.

On the role of human herpesvirus 6 in viral latency in nervous tissue and in cerebral lymphoma

Latent infections by human herpesvirus 6 (HHV6) in nervous tissue and its role in human disease are poorly understood. For the present study, an improved PCR method has been applied to brain tissue samples from 5 different brain regions from 20 forensic post-mortem cases without neurologic involvement. Spleen tissue from these cases as well as 5 cerebral lymphoma tissue samples were also examined. HHV6 DNA was detected in 3 of 20 brains. The viral sequences could be amplified from cortical brain tissue from these 3 cases. In one of these cases, HHV6 DNA was detectable in two separate tissue samples. PCR was negative in brain lymphoma and spleen tissue. These findings point toward HHV6 latency in brain tissue and might thus support the reported glial tropism of this virus. No role could be found for HHV6 in the pathogenesis of cerebral lymphoma.

Rate of detection of human herpesvirus-6 at different stages of HIV infection

In a cross-sectional study, human herpesvirus-6 (HHV-6) infection was analysed by means of polymerase chain reaction in peripheral blood mononuclear cells (PBMCs) and saliva from 125 HIV-seropositive subjects and 29 HIV-seronegative controls. HHV-6 was detected in saliva significantly more frequently in HIV-seronegative subjects than in HIV-seropositive subjects (p = 0.023), with no significant difference between HIV-seropositive subgroups. The HIV proviral copy number in PBMCs differed significantly according to HIV subgroup, as expected, but did not differ according to either the presence of HHV-6 or the number of HHV-6 copies in PBMCs. All the HHV-6 identified were variant B except for one variant A strain detected in saliva from a healthy subject. These results do not support the hypothesis that there is synergistic activation of HHV-6 infection in the course of HIV infection.

Detection of human herpesvirus 6 DNAs in samples from several body sites of patients with exanthem subitum and their mothers by polymerase chain reaction assay

Polymerase chain reaction amplification was used to detect human herpesvirus 6 (HHV-6) DNAs in peripheral blood mononuclear cells (MNCs), plasma, saliva, stool, and urine from three patients with exanthem subitum and in peripheral blood MNCs, plasma, and saliva from their mothers. HHV-6 DNAs were detected in MNCs during and after the disease and were found in plasma only in the acute phase. The virus DNAs were also detected in saliva after recovery from the illness and were found persistently or intermittently in stool but not in urine samples after the onset of the disease. In contrast, one of the three mothers excreted HHV-6 DNAs persistently in saliva. None of the mothers had the virus DNAs in peripheral blood MNCs and plasma nor a significant increase in antibody titers to HHV-6 after possible exposure from their children. These findings suggest systemic replication of HHV-6 during the acute phase in patients with exanthem subitum and persistent infection of the virus in several organs after recovery from the disease.

Human herpesviruses 6 and 7 in salivary glands and shedding in saliva of healthy and human immunodeficiency virus positive individuals

The presence of human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) was investigated by the polymerase chain reaction in saliva specimens from healthy persons, donors affected by common cold or recurrent aphthous ulceration (RAU), and human immunodeficiency virus (HIV) positive patients, and in salivary gland biopsies. The sensitivity of the technique made it possible to detect as few as 5-10 target molecules in 15 microliters of saliva. HHV-6 was present in 63% of salivary gland biopsies and in 3% of salivas from healthy persons. No significant difference in the presence of HHV-6 was detected in specimens from donors with common cold, RAU, or HIV-infected patients. HHV-7 was present in 75% of salivary glands and in 55% of salivas from healthy persons. HHV-7 was detected with similar frequency in salivas from donors with common cold or RAU. Salivas from HIV-infected patients harbored HHV-7 with higher frequency (81%) and increased viral load. These results show that salivary glands are a site of persistent infection for both HHV-6 and HHV-7. However, the two viruses seem to differ in their biological properties: 1) HHV-6 is rarely present in saliva in detectable amounts, while HHV-7 is frequently detected; and 2) immunosuppression by acquired immunodeficiency syndrome (AIDS) increases the frequency of detection and the viral load of HHV-7, but does not have a significant effect on HHV-6 shedding in saliva.