Human herpesvirus 6 (HHV6) infection

Viruses of the oral cavity: Prevalence, pathobiology and association with oral diseases

The human oral cavity contains a plethora of habitats and tissue environments, such as teeth, tongue, and gingiva, which are home to a rich microbial flora including bacteria, fungi, and viruses. Given the exposed nature of the mouth, oral tissues constantly encounter infectious agents, forming a complex ecological community. In the past, the discussion of microbiological aspects of oral disease has traditionally focused on bacteria and fungi, but viruses are attracting increasing attention as pathogens in oral inflammatory diseases. Therefore, understanding viral prevalence, pathogenicity, and preference regarding oral tissues is critical to understanding the holistic effects of viruses on oral infections. Recent investigations have demonstrated the abundance of certain viruses in oral inflammatory diseases, suggesting an association between viruses and disease. Human herpesviruses are the most extensively studied viruses in different oral inflammatory diseases. However, challenges in viral detection and the lack of reproducible in vitro and in vivo infection models have limited our progress in understanding viruses and their contribution to oral diseases. This review presents a summary of major mammalian viruses and associated diseases in the human oral cavity. The emergence of a recent pathogen SARS-CoV-2 and its tropism for salivary and periodontal tissues further highlights the relevance of the oral cavity in host-pathogen interaction. Understanding how these different viruses present clinically and influence oral health will advance our understanding of multifactorial oral diseases and their association with viruses.

Human herpesvirus 6 associated post-transplant acute limbic encephalitis: Clinical observations of biomarkers for risk of seizure in a pediatric population

BACKGROUND

Human herpesvirus 6 (HHV6) is a cause of post-transplant acute limbic encephalitis (PALE). Seizures are associated with this disorder yet no predictive biomarkers have been identified. The objective of this study was to evaluate lab and neurodiagnostic biomarkers in patients with HHV6 associated PALE.

METHODS

A retrospective chart review was performed at our institutions between 2000 and 2017. Patients were identified through a clinical database. Inclusion criteria included: age less than 18 years, HHV6 (quantitative real-time PCR or meningoencephalitis panel) tested in CSF and serum. Biomarkers of serum and CSF viral load, EEG, and MRI were reviewed along with clinical data.

RESULTS

In total, 11 patients met inclusion criteria. All patients had undergone hematopoietic stem cell transplantation. Five of 11 patients had seizures as part of their clinical course, all being controlled with antiepileptic monotherapy. Seizure semiology was focal-onset in three cases and generalized in two. Neuroimaging was normal in all patients within seven days but six patients developed T2 signal intensities in the temporal lobes on repeat imaging between 14-28 days. The median CSF HHV6 viral load for all patients was 47 300 copies/mL although the median viral load was 2586 copies/mL in patients who had seizure compared to 473 969 copies/mL in those who had not (P = 0.02). Those with seizures tended to be younger (median 6.5 years compared to 11 years, P = 0.27). All patients with seizures had an EEG with 80% demonstrating abnormalities.

CONCLUSION

In patients with post-hematopoietic stem cell transplant HHV6 associated PALE, lower CSF viral load may be associated with a higher likelihood to have seizures. This may indicate a primary infection as opposed to secondary reactivation phenomenon.

Chemokines encoded by herpesviruses

Viruses use diverse strategies to elude the immune system, including copying and repurposing host cytokine and cytokine receptor genes. For herpesviruses, the chemokine system of chemotactic cytokines and receptors is a common source of copied genes. Here, we review the current state of knowledge about herpesvirus-encoded chemokines and discuss their possible roles in viral pathogenesis, as well as their clinical potential as novel anti-inflammatory agents or targets for new antiviral strategies.

The Role of Cytokines, Chemokines, and Growth Factors in the Pathogenesis of Pityriasis Rosea

Introduction. Pityriasis rosea (PR) is an exanthematous disease related to human herpesvirus- (HHV-) 6/7 reactivation. The network of mediators involved in recruiting the infiltrating inflammatory cells has never been studied. Object. To investigate the levels of serum cytokines, growth factors, and chemokines in PR and healthy controls in order to elucidate the PR pathogenesis. Materials and Methods. Interleukin- (IL-) 1, IL-6, IL-17, interferon- (IFN-) γ, tumor necrosis factor- (TNF-) α, vascular endothelial growth factor (VEGF), granulocyte colony stimulating factor (G-CSF), and chemokines, CXCL8 (IL-8) and CXCL10 (IP-10), were measured simultaneously by a multiplex assay in early acute PR patients' sera and healthy controls. Subsequently, sera from PR patients were analysed at 3 different times (0, 15, and 30 days). Results and discussion. Serum levels of IL-17, IFN-γ, VEGF, and IP-10 resulted to be upregulated in PR patients compared to controls. IL-17 has a key role in host defense against pathogens stimulating the release of proinflammatory cytokines/chemokines. IFN-γ has a direct antiviral activity promoting NK cells and virus specific T cells cytotoxicity. VEGF stimulates vasculogenesis and angiogenesis. IP-10 can induce chemotaxis, apoptosis, cell growth, and angiogenesis. Conclusions. Our findings suggest that these inflammatory mediators may modulate PR pathogenesis in synergistic manner.

Clinical consequences of human herpesvirus-6 DNAemia in peripheral blood in pediatric liver transplant recipients

The significance of HHV6 DNAemia after solid organ transplantation has not been fully determined. Our objectives were to determine the prevalence of HHV6 DNAemia in pediatric liver transplant recipients and to describe the associated clinical characteristics and outcomes. This was a retrospective case-control study. Eligible liver transplant patients aged ≤ 18 yr with HHV6 DNAemia were matched with two subjects without HHV6 DNAemia. Matching was by age ± 6 months. Among 154 subjects, 25 patients (16%) had HHV6 DNAemia detected by PCR in whole blood or plasma (M:F ratio = 0.9:1). While 28% of subjects with DNAemia (7/25) had symptoms consistent with HHV6 infection, active infection was detected in only four subjects (2.6% of liver transplant patients). The major symptoms/signs were fever, vomiting, lethargy, splenomegaly, bone marrow suppression, and elevated transaminases. The prevalence of DNAemia due to other herpesviruses in cases vs. controls was EBV 56% vs. 60%, CMV 12% vs. 12%, HHV7 20% vs. 12%; p value is not significant for all pairwise comparisons. HHV6 DNAemia in pediatric liver transplant patients is not an uncommon entity. While the clinical relevance is still not entirely established, active HHV6 infection and attributable symptoms are relatively rare.

Herpesviruses and the microbiome

The focus of this article will be to examine the role of common herpesviruses as a component of the microbiome of atopic patients and to review clinical observations suggesting that atopic patients might be predisposed to more severe and atypical herpes-related illness because their immune response is biased toward a TH2 cytokine profile. Human populations are infected with 8 herpesviruses, including herpes simplex virus HSV1 and HSV2 (also termed HHV1 and HHV2), varicella zoster virus (VZV or HHV3), EBV (HHV4), cytomegalovirus (HHV5), HHV6, HHV7, and Kaposi sarcoma-associated herpesvirus (termed KSV or HHV8). Herpesviruses are highly adapted to lifelong infection of their human hosts and thus can be considered a component of the human "microbiome" in addition to their role in illness triggered by primary infection. HSV1 and HSV2 infection and reactivation can present with more severe cutaneous symptoms termed eczema herpeticum in the atopic population, similar to the more severe eczema vaccinatum, and drug reaction with eosinophilia and systemic symptoms syndrome (DRESS) is associated with reactivation of HSV6 and possibly other herpesviruses in both atopic and nonatopic patients. In this review evidence is reviewed that primary infection with herpesviruses may have an atypical presentation in the atopic patient and conversely that childhood infection might alter the atopic phenotype. Reactivation of latent herpesviruses can directly alter host cytokine profiles through viral expression of cytokine-like proteins, such as IL-10 (EBV) or IL-6 (cytomegalovirus and HHV8), viral encoded and secreted siRNA and microRNAs, and modulation of expression of host transcription pathways, such as nuclear factor κB. Physicians caring for allergic and atopic populations should be aware of common and uncommon presentations of herpes-related disease in atopic patients to provide accurate diagnosis and avoid unnecessary laboratory testing or incorrect diagnosis of other conditions, such as drug allergy or autoimmune disease. Antiviral therapy and vaccines should be administered promptly when indicated clinically.

Human herpes 6 virus encephalitis complicating allogeneic hematopoietic stem cell transplantation

OBJECTIVE

To describe the presentation and management of encephalitis due to human herpes 6 virus (HHV-6) in patients who underwent allogeneic hematopoietic stem cell transplant (alloHSCT), via retrospective chart review.

METHODS

Of the 243 patients who underwent alloHSCT at the NIH Clinical Center during 2009 to 2011, we retrospectively analyzed 9 diagnosed with HHV-6 encephalitis post-alloHSCT.

RESULTS

Eight men and 1 woman (aged 19-60 years) met diagnostic criteria for study inclusion. The median time from HSCT to initial symptoms was 21 days. All patients presented with altered mental status and headaches. Seven patients had amnesia and 2 presented with fever of unknown etiology. Four patients had clinical seizures during the disease course. Brain MRI within 7 days was normal in all patients. Repeat MRI after 7 days showed hyperintensity in the limbic area in 3 patients. On initial testing, CSF analysis indicated acellularity and normal or minimally elevated protein; presence of HHV-6 was detected by PCR. After 7 days, mildly elevated protein and minimal pleocytosis were noted. Ganciclovir, foscarnet, or valganciclovir alone or in combination was initiated with subsequent improvement. Four patients remained alive at 1 year posttransplant; 2 had persistent memory deficits. Presence of encephalitis was associated with higher mortality post-alloHSCT.

CONCLUSION

High clinical suspicion and CSF PCR testing are important for early diagnosis of HHV-6 encephalitis post-HSCT. Abnormalities on brain MRI or CSF testing may be minimal and delayed. Diagnosis and management of HHV-6 encephalitis is challenging, and a larger prospective study is needed for further research.

Co-infection and clinical impact of human herpesvirus 5 and 6 in liver transplantation

BACKGROUND

Human herpesvirus (HHV) 5 and 6 remain latent after primary infection and can be reactivated after immunosuppression for organ transplantation. An association between HHV-5 and HHV-6 has been reported in liver transplant patients. The coinfection is associated with clinical manifestations and graft dysfunction.

OBJECTIVE

The aim of this study was to monitor herpesviruses in liver transplant recipients to better understand issues involving coinfection with HHV-5/6 and correlations with acute cellular rejection episodes and bacterial infections.

METHODS

Forty-five adult liver transplant patients of median age 47 years (range, 18-66), gave blood samples and liver biopsies in the first 6 months after their surgeries. Viremia was detected with the use of nested PCR and antigenemia; the Banff classification was used to detect allograft rejection.

RESULTS

IgG positive for HHV-5 was observed in 94% of subjects whose main indication (67%) for transplantation was hepatitis C. Twenty-three (51.1%) displayed cytomeg virus (CMV) infections and 12 (26.7%) HHV-6 infection. There were 6 patients (13.3%) with HHV-5/6 coinfections. Eighteen of the 23 patients had CMV disease, showing a strong correlation between a positive test and CMV disease; 6 displayed an acute cellular rejection episode in the same period (χ(2) = 6.62; P < .03). Four out of 6 patients who displayed coinfections (HHV-5/6) had concomitant bacterial infections; 3/6 experienced graft rejection episodes. During follow-up, 1 patient had HHV-6 infection diagnosed as encephalitis followed by fever on the 24th day after surgery. The median 32 days for HHV-6 detection by nested PCR positivity was shorter than 38 days for HHV-5.

CONCLUSIONS

HHV-5/6-infected patients displayed more allograft rejection episodes, coinfections, and concomitant bacterial infections, besides an higher risk for CMV disease.

Development of a microwell adapted immunoblot system with recombinant antigens for distinguishing human herpesvirus (HHV)6A and HHV6B and detection of human cytomegalovirus

BACKGROUND

The human cytomegalovirus (HCMV) and the human herpesvirus 6 (HHV6) are widely distributed in the human population. The variants A and B of HHV6 are closely related to each other and cannot be distinguished by common serological methods like enzyme-linked immunosorbent assay (ELISA) or immunofluorescence test (IFT). The aim of this study was to develop a microwell-adapted blot system for specificity detection of human cytomegalovirus and human herpesvirus 6A and 6B (HHV6A, HHV6B) that combines the advantages of ELISA (automation and multiplex detection) and immunoblotting (antigen-specific antibody detection with high specificity).

METHODS

Ten HCMV, five HHV6A and five HHV6B antigens were expressed as fusion proteins and tested with sera of children (n=30), of healthy young adults (n=30) and of older adults (n=30) in a newly developed microblot system.

RESULTS

Sensitivity and specificity of HCMV and HHV6 microblots were comparable to commercially available[ELISA, IFT and to line assay tests. The advantage of the HHV6 microblot is the possibility of distinguishing between HHV6A-monovalent sera, HHV6B-monovalent sera and HHV6A/B-polyvalent sera. Most sera of children younger than 2 years showed only HHV6B antigen positivity, while most sera of adults and children aged over 2 years reacted with HHV6A and B proteins, although predominance for HHV6B was observed.

CONCLUSIONS

The authors were able to detect HCMV positive sera and to distinguish between HHV6A-monovalent sera, HHV6B-monovalent sera and HHVA/B-polyvalent sera with the new developed microblot system. Predominance of HHV6B was observed in sera of children and adults.

Simultaneous monitoring of CMV and human herpesvirus 6 infections and diseases in liver transplant patients: one-year follow-up

OBJECTIVE

The aim of this study was to simultaneously monitoring cytomegalovirus and human herpesvirus 6 active infections using nested-polymerase chain reaction and, together with clinical findings, follow the clinical status of patients undergoing liver transplant.

INTRODUCTION

The human β-herpesviruses, including cytomegalovirus and human herpesvirus 6, are ubiquitous among human populations. Active infections of human herpesvirus 6 and cytomegalovirus are common after liver transplantation, possibly induced and facilitated by allograft rejection and immunosuppressive therapy. Both viruses affect the success of the transplant procedure.

METHODS

Thirty patients submitted to liver transplant at the Liver Transplant Unit, at the Gastro Center, State University of Campinas, SP, Brazil, were studied prospectively from six months to one year, nested-polymerase chain reaction for cytomegalovirus and human herpesvirus 6 DNA detections. Two or more consecutive positive nested-polymerase chain reaction were considered indicative of active infection.

RESULTS

Active infection by cytomegalovirus was detected in 13/30 (43.3%) patients, median time to first cytomegalovirus detection was 29 days after transplantation (range: 0-99 days). Active infection by human herpesvirus 6 was detected in 12/30 (40%) patients, median time to first human herpesvirus 6 detection was 23.5 days after transplantation (range: 0-273 days). The time-related appearance of each virus was not statistically different (p = 0.49). Rejection of the transplanted liver was observed in 16.7% (5/30) of the patients. The present analysis showed that human herpesvirus 6 and/or cytomegalovirus active infections were frequent in liver transplant recipients at our center.

CONCLUSIONS

Few patients remain free of betaherpesviruses after liver transplantation. Most patients presenting active infection with more than one virus were infected sequentially and not concurrently. Nested-polymerase chain reaction can be considered of limited value for clinically monitoring cytomegalovirus and human herpesvirus 6.

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.

Assessment of salivary human herpesvirus-6 and immunoglobulin a levels in nurses working shifts

PURPOSE

The purpose of the present study was to assess whether salivary human herpesvirus (HHV)-6 acted as a new sensitive stress marker, providing a reliable indicator of stress among shift work nurses. Salivary HHV-6, immunoglobulin (Ig) A and mood states were compared among nurses who worked day shifts only and nurses who worked different numbers of night shifts.

METHODS

Participants included 56 female nurses working in Japanese general hospitals. The 56 subjects were categorized into three groups: Group A (n = 7), which consisted of nurses who only worked day shifts; group B (n = 29), which consisted of nurses working shifts with £8 night shifts per month; and group C (n = 20), which consisted of nurses working shifts with (3) 9 night shifts per month. Mood was assessed using the Profile of Mood States Short Form Japanese version (POMS-SFJ). Salivary biomarker levels and mood were compared among the three groups.

RESULTS

Although the salivary HHV-6 level was significantly higher in group C than in group A (p < .05), salivary IgA and mood levels were not significantly different among the three groups.

CONCLUSION

Salivary HHV-6 level may be a more sensitive stress marker than salivary IgA or mood for assessing chronic fatigue in nurses working shifts. Improvement to shift assignments using assessment by salivary HHV-6 is required.

Multiplex detection of human herpesviruses from archival specimens by using matrix-assisted laser desorption ionization-time of flight mass spectrometry

The human herpesviruses are involved in a variety of diseases. Large-scale evaluation of the clinical and epidemiological importance of different herpesviruses requires high-throughput methods. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a method that has a multiplex capacity enabling simultaneous detection of several viruses in a single sample. PCR-based methods for the multiplex detection of all known human herpesviruses were developed on the MALDI-TOF MS system. A variety of 882 archival samples, including bronchoalveolar lavage, conjunctival fluid, sore secretion, blister material, plasma, serum, and urine, analyzed for herpesviruses using PCR-based reference methods, were used to evaluate the MALDI-TOF MS method. The overall concordance rate between the MALDI-TOF MS method and the reference methods was 95.6% (kappa = 0.90). In summary, the MALDI-TOF MS method is well suited for large-scale detection of all known human herpesviruses in a wide variety of archival biological specimens.

Bacterial and viral skin diseases

At least two populations of microorganisms are found in skin microbiota: a resident flora and a transient flora. Colonization and invasion by pathogenous microorganisms is counteracted both by the host defenses and by the resident flora. Most skin infections are therefore self-limiting in healthy subjects and are defined as primary infections. Secondary infections develop on preexisting skin lesions and are usually polymicrobial and caused by microorganisms that in themselves have little pathogenic power. When immune defenses are low, secondary infections arise readily and develop rapidly. This article describes the main bacterial and viral skin diseases.