Human herpesvirus 7 is a T-lymphotropic virus and is related to, but significantly different from, human herpesvirus 6 and human cytomegalovirus

Update on human herpesvirus 7 pathogenesis and clinical aspects as a roadmap for future research

Human herpesvirus 7 (HHV-7) is a common virus that is associated with various human diseases including febrile syndromes, dermatological lesions, neurological defects, and transplant complications. Still, HHV-7 remains one of the least studied members of all human betaherpesviruses. In addition, HHV-7-related research is mostly confined to case reports, while in vitro or in vivo studies unraveling basic virology, transmission mechanisms, and viral pathogenesis are sparse. Here, we discuss HHV-7-related literature linking clinical syndromes to the viral life cycle, epidemiology, and viral immunopathogenesis. Based on our review, we propose a hypothetical model of HHV-7 pathogenesis inside its host. Furthermore, we identify important knowledge gaps and recommendations for future research to better understand HHV-7 diseases and improve therapeutic interventions.

Integrated chromosomal instability and tumor microbiome redefined prognosis-related subtypes of pancreatic cancer

BACKGROUND

Pancreatic cancer is a common malignancy with poor prognosis and limited treatment. Here we aimed to investigate the role of host chromosomal instability (CIN) and tumor microbiome in the prognosis of pancreatic cancer patients.

METHODS

One hundred formalin-fixed paraffin-embedded (FFPE) pancreatic cancer samples were collected. DNA extracted from FFPE samples were analyzed by low-coverage whole-genome sequencing (WGS) via a customized bioinformatics workflow named ultrasensitive chromosomal aneuploidy detector.

RESULTS

Samples are tested according to the procedure of ultrasensitive chromosomal aneuploidy detector (UCAD). We excluded 2 samples with failed quality control, 1 patient lost to follow-up and 6 dead in the perioperative period. The final 91 patients were admitted for the following analyses. Thirteen (14.3%) patients with higher CIN score had worse overall survival (OS) than those with lower CIN score. The top 20 microbes in pancreatic cancer samples included 15 species of bacteria and 5 species of viruses. Patients with high human herpesvirus (HHV)-7 and HHV-5 DNA reads exhibited worse OS. Furthermore, we classified 91 patients into 3 subtypes. Patients with higher CIN score (n =13) had the worst prognosis (median OS 6.9 mon); patients with lower CIN score but with HHV-7/5 DNA load (n = 24) had worse prognosis (median OS 10.6 mon); while patients with lower CIN score and HHV-7/5 DNA negative (n = 54) had the best prognosis (median OS 21.1 mon).

CONCLUSIONS

High CIN and HHV-7/5 DNA load were associated with worse survival of pancreatic cancer. The novel molecular subtypes of pancreatic cancer based on CIN and microbiome had prognostic value.

Meningitis associated with HHV-7 in an Iranian immunocompetent adolescent girl

There is limited literature regarding meningitis associated with HHV-7. This article reports an immunocompetent adolescent girl who developed fever, headache, and meningism which CSF molecular analysis with PCR was positive only for HHV-7. Interestingly, persistent cavum septum pellucidum and cavum vergae were observed on brain magnetic resonance imaging. The patient received antibiotics, dexamethasone, and acyclovir and then she gained full recovery. HHV-7 is a rare and yet possible pathogen in patients with meningitis, and this is the first described case report from Iran.

Anterior Uveitis Associated with Human Herpesvirus 7 Infection Diagnosed by Multiplex Polymerase Chain Reaction Assay: A Case Report

BACKGROUND

Herpetic anterior uveitis (AU) is usually caused by the herpes simplex virus, varicella-zoster virus, and cytomegalovirus. Herein, we report a case of herpetic AU associated with human herpesvirus 7 (HHV-7) infection.

STUDY DESIGN

A case report.

CASE PRESENTATION

A 49-year-old female patient presented with complaints of blurred vision and hyperemia in the right eye. Slit-lamp examination revealed bilateral fine and a few small white keratic precipitates (KPs), Descemet membrane folds in the right eye, and severe and mild cellular infiltration in the anterior chamber of the right and left eye, respectively. HHV-7 viral DNA was detected by a polymerase chain reaction assay of an aqueous humor sample. The AU improved significantly with topical steroids.

CONCLUSION

We report a rare case of herpetic AU characterized by fine and small white KPs in which only HHV-7 DNA was detected in the aqueous humor.

Family Herpesviridae and neuroinfections: current status and research in progress

This article addresses the relationship between human herpesviruses (HHVs) and neuroinfections. Alphaherpesviruses, betaherpesviruses and gammaherpesviruses are neurotropic viruses that establish latency and exhibit reactivation capacity. Encephalitis and meningitis are common in cases of HHV. The condition promoted by HHV infection is a purported trigger for certain neurodegenerative diseases. Ongoing studies have identified an association between HSV-1 and the occurrence of Alzheimer's disease, multiple sclerosis and infections by HHV-6 and Epstein-Barr virus. In this review, we highlight the importance of research investigating the role of herpesviruses in the pathogenesis of diseases that affect the nervous system and describe other studies in progress.

Case Report: Overlapping Syndrome of Anti-NMDAR Encephalitis and MOG Inflammatory Demyelinating Disease in a Patient With Human Herpesviruses 7 Infection

Objectives

This study reported a case of overlapping anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis and myelin oligodendrocyte glycoprotein (MOG) inflammatory demyelinating disease with human herpesviruses 7 (HHV-7) infection.

Methods

The detailed clinical characteristics, neuroimaging features, and outcomes of the patient were collected. Polymerase chain reaction (PCR), cell-based assay (CBA) and the tissue-based indirect immunofluorescence assay (TBA) were used for diagnosis.

Results

The clinical manifestations included headache, dizziness, fever, optic neuritis, and epileptic-seizures. Brain magnetic resonance imaging (MRI) showed hyperintensities involving the left frontal, orbital gyrus and bilateral optic nerve with substantial contrast enhancement. Moreover, test for HHV-7 DNA by using the next generation sequencing metagenomics and polymerase chain reaction showed positive result in CSF but not in the serum samples. Anti-HHV-7 IgM and IgG antibodies were detected in both the serum and cerebrospinal fluid. NMDAR antibodies (1:10) were found positive in the patient’s CSF by a cell-based assay, and MOG antibodies were positive in the serum (1:10) and CSF (1:32). The patient appeared to respond well to immune therapy and it was found that the clinical symptoms including epileptic-seizure as well as headache were relieved and cerebral lesions almost disappeared after the treatment. However, his vision was not completely restored even at the 8-month follow-up, especially the vision in his right eye which was more seriously damaged.

Discussion

We report a rare case of MOG antibodies and anti-NMDAR encephalitis overlapping syndrome (MNOS) with HHV-7 infection for the first time. The possibility of MNOS needs be considered when optic neuritis occurs in the patients diagnosed with anti-NMDAR encephalitis. Besides, immunotherapy should be initiated as early as possible to improve the treatment outcomes and facilitate complete cure.

Human Herpesvirus-6 and -7 in the Brain Microenvironment of Persons with Neurological Pathology and Healthy People

During persistent human beta-herpesvirus (HHV) infection, clinical manifestations may not appear. However, the lifelong influence of HHV is often associated with pathological changes in the central nervous system. Herein, we evaluated possible associations between immunoexpression of HHV-6, -7, and cellular immune response across different brain regions. The study aimed to explore HHV-6, -7 infection within the cortical lobes in cases of unspecified encephalopathy (UEP) and nonpathological conditions. We confirmed the presence of viral DNA by nPCR and viral antigens by immunohistochemistry. Overall, we have shown a significant increase (p < 0.001) of HHV antigen expression, especially HHV-7 in the temporal gray matter. Although HHV-infected neurons were found notably in the case of HHV-7, our observations suggest that higher (p < 0.001) cell tropism is associated with glial and endothelial cells in both UEP group and controls. HHV-6, predominantly detected in oligodendrocytes (p < 0.001), and HHV-7, predominantly detected in both astrocytes and oligodendrocytes (p < 0.001), exhibit varying effects on neural homeostasis. This indicates a high number (p < 0.001) of activated microglia observed in the temporal lobe in the UEP group. The question remains of whether human HHV contributes to neurological diseases or are markers for some aspect of the disease process.

Human Herpes Virus 7-related encephalopathy in children

BACKGROUND

Primary HHV7 infection is almost ubiquitous, and it can present as exanthema subitem. Little is known on the clinical relevance of HHV7 neuroinvasion in immunocompetent children.

METHODS

We describe 12 patients (median age 9.45 years, 50% males) with acute encephalopathy and active HHV7 infection. In all patients, HHV7-DNA was detected on cerebrospinal fluid (CSF) by RT-PCR.

RESULTS

7/12 patients had meningoencephalitis (two with ADEM and one with MOG antibody-associated CIS); 5/12 showed acute neuropsychiatric symptoms. EEG showed anomalies exclusively in patients with meningoencephalitis. Six patients had RMN anomalies. CSF HHV7 copies ranged between 20 and 3,500 copies/mL (median 66 copies/mL) and mean HHV7 CSF/blood ratio was 0.75. Outcome was favorable in all children, although 3/12 had minor neurobehavioral sequelae. Mean follow-up period of 5.2 months.

CONCLUSIONS

HHV7 can determine neuroinvasion in immunocompetent children, leading to acute encephalopathy. Blood-brain barrier damage and high CSF/blood viral copies ratio correlated with a more severe presentation. We speculate on the importance of immune-mediated mechanisms in provoking clinical features.

Inflammatory Cytokine-Producing Cells and Inflammation Markers in the Synovium of Osteoarthritis Patients Evidenced in Human Herpesvirus 7 Infection

A direct association between joint inflammation and the progression of osteoarthritis (OA) has been proposed, and synovitis is considered a powerful driver of the disease. Among infections implicated in the development of joint disease, human herpesvirus 7 (HHV-7) infection remains poorly characterized. Therefore, we assessed synovitis in OA patients; determined the occurrence and distribution of the HHV-7 antigen within the synovial membrane of OA-affected subjects; and correlated plasma levels of the pro-inflammatory cytokines tumor necrosis factor (TNF), interleukin-6 (IL-6), and TNF expressed locally within lesioned synovial tissues with HHV-7 observations, suggesting differences in persistent latent and active infection. Synovial HHV-7, CD4, CD68, and TNF antigens were detected immunohistochemically. The plasma levels of TNF and IL-6 were measured by an enzyme-linked immunosorbent assay. Our findings confirm the presence of persistent HHV-7 infection in 81.5% and reactivation in 20.5% of patients. In 35.2% of patients, virus-specific DNA was extracted from synovial membrane tissue samples. We evidenced the absence of histopathologically detectable synovitis and low-grade changes in the majority of OA patients enrolled in the study, in both HHV-7 PCR+ and HHV-7 PCR‒ groups. The number of synovial CD4-positive cells in the HHV-7 polymerase chain reaction (PCR)+ group was significantly higher than that in the HHV-7 PCR‒ group. CD4- and CD68-positive cells were differently distributed in both HHV-7 PCR+ and HHV-7 PCR‒ groups, as well as in latent and active HHV-7 infection. The number of TNF+ and HHV-7+ lymphocytes, as well as HHV-7+ vascular endothelial cells, was strongly correlated. Vascular endothelial cells, especially in the case of infection reactivation, appeared vulnerable. The balance between virus latency and reactivation is a long-term relationship between the host and infectious agent, and the immune system appears to be involved in displaying overreaction when a shift in the established equilibrium develops.

Persistent Roseoloviruses Infection in Adult Patients with Epilepsy

Background: Human herpesviruses (HHV)-6A, HHV-6B and HHV-7 are considered to be involved in the pathogenesis of epilepsy, a common neurological disorder. The objective of this study was to determine the association of roseoloviruses infection with epilepsy. Methods: 53 epilepsy patients and 104 ordinary blood donors were analyzed to determine presence of virus-specific antibodies by enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assay (IFA), genomic sequences, viral load and gene expression by polymerase chain reactions (PCRs) and restriction analysis, HHV-6 protein expression by IFA and level of cytokines by ELISA. Results: Roseoloviruses genomic sequences in DNA samples from whole blood were found in 86.8% of patients versus 54.8% of controls and active infection was revealed only in patients with epilepsy (19.6% of roseolovirus-positive patients). Significantly higher viral load and more frequent gene expression was detected in patients compared to the controls. HHV-6-encoded protein expression was demonstrated in 53.3% of patients with previously detected HHV-6 DNA. Changes in level of cytokines were determined in patients with elevated viral load compared to the patients without elevated viral loads and to the controls. Conclusions: Results on frequent active HHV-6 and HHV-7 infection in epilepsy patient’ peripheral blood indicate on possible involvement of these viruses in the disease development.

Proportion of the CD19-Positive and CD19-Negative Lymphocytes and Monocytes within the Peripheral Blood Mononuclear Cell Set is Characteristic for Rheumatoid Arthritis

Background and objectives: Composition of the peripheral blood (PB) cell populations and their activation state reflect the immune status of a patient. Rheumatoid arthritis (RA) is characterized by abnormal B- and T-cell functions. The objective of this study was to assess the profiles of the PB mononuclear cell (PBMC) populations in patients with rheumatoid and osteoarthritis (OA) in comparison with healthy control (HC) subjects in order to evaluate the PBMC profiles as a potential diagnostic characteristic in RA. The second aim was to assess the CCR1 and CCR2 expression on PB lymphocytes and correlate it with the plasma levels of matrix metallopeptidase 9 (MMP-9), IL-17F, TNF-α, IL-6, and IL-10. Materials and Methods: The frequency and phenotype, including CCR1 and CCR2, of the PBMC populations (monocytes, CD19⁺B cells, and T/NK lymphocytes) in RA (n = 15) and OA (n = 10) patients and HC (n = 12) were analyzed by five-color flow cytometry. DNA of the viruses, HHV-6, HHV-7, and B19, in the whole blood and cell-free plasma, were assessed by nested-polymerase chain reaction (PCR). Results: Active persistent or acute infections, caused by HHV-6, HHV-7, or B19, were not detected in patients of this study. Both CCR1 and CCR2 were determined on the PB B and T/NK lymphocytes in several RA and OA patients and HCs. However, in patients, the frequency of the CCR1-positive T/NK lymphocytes showed a weak negative correlation with the IL-10 level, while the frequency of the CCR2-positive B cells correlated positively with the level of IL-6. Statistically significant differences in the proportions of the CD19-positive and CD19-negative lymphocyte and monocyte subsets within the PBMC set were determined between RA and OA patients and HC adults. Conclusions: We have shown in our pilot study with rather small cohorts of patients that the PBMC-population profiles were very consistent, and statistically significantly differed between RA and OA patients and HC subjects.

Detection of human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) DNA in endocervical samples from a positive and negative HPV woman of Córdoba, Argentina

AIMS

The purpose of the present study was to elucidate the presence of human herpesvirus 6A (HHV-6A), HHV-6B and HHV-7 in samples of the uterine cervix through detection of viral DNA. We analysed normal tissues, samples with low-grade squamous intraepithelial lesions (LSILs) and high-grade squamous intraepithelial lesions (HSILs). We correlated the presence of HHV-6 and HHV-7 with the finding of human papillomavirus (HPV) in mucosal samples.

METHODS

Cervical samples were examined and grouped as follows: group 1 (n=29), normal cytology; group 2 (n=61), samples with LSIL; group 3 (n=35), samples with HSIL. Molecular biology examinations were performed in all samples to detect HHV-6, HHV-7 and HPV DNA and to typify HHV-6 species.

RESULTS

Group 1: normal cytology and HPV (-): HHV-6: 6.8% (2/29), HHV-7: 79.3% (23/29); group 2: LSIL and HPV (-): HHV-6: 93.1% (27/29), HHV-7: 96.5% (28/29); LSIL and HPV (+): HHV-6: 0% (0/32), HHV-7: 90.6% (29/32); group 3: HSIL and HPV (-): HHV-6: 20% (2/10), HHV-7: 70% (7/10); HSIL HPV (+): HHV-6: 12% (3/25), HHV-7: 68% (17/25). HHV-6A DNA was not detected in any samples.

CONCLUSIONS

(1) Both HHV-6 and HHV-7 infect the mucosal cells of the cervix with higher prevalence of HHV-7. (2) The higher prevalence of HHV-6 in LSIL HPV (-) samples compared with those with normal cytology indicates that it constitutes a possible risk factor for atypia production. (3) The presence of HHV-7 in all samples questions its role in the production of atypia. (4) The finding of HHV-6 and HHV-7 suggests that the cervical mucosa is a possible transmission pathway for these viruses.

Age-Related Patterns of DNA Detection and Specific IgG Subclasses in Healthy HHV-6- and HHV-7-Infected Individuals

Human herpesvirus 6A (HHV-6A), Human herpesvirus 6B (HHV-6B), and Human herpesvirus 7 (HHV-7) can persist by establishing a lifelong infection which could have implications on the immunocompetent host. The aim of this work is to contribute with some knowledge about the HHV-6 A/B and HHV-7 infection in healthy individuals. We have carried out a longitudinal study in seropositive healthy individuals for the detection of viral DNA in saliva and plasma samples, and for determining a specific IgG isotype immune response, which enabled the performance of these viruses to be observed over time. Furthermore, an elderly population was transversely studied to provide data of the activity of these viruses in the older population. In the longitudinal study, HHV-6 DNA was occasionally detected and an isotype immune response with a specific IgG1 profile, while in the older group HHV-6 DNA was frequently detected and an isotype immune response with specific IgG1, IgG3, and IgG4. HHV-7 DNA was frequently detected in both groups and isotype patterns of specific IgG1, IgG3, and IgG4. The results of this study highlight that the long-lasting relationship in healthy HHV-6 A/B-infected individuals have the imprint of age groups.

The role of HHV-6 and HHV-7 infections in the development of fibromyalgia

Human herpes virus-6 (HHV-6) and human herpes virus-7 (HHV-7) are immunomodulating viruses potentially affecting the nervous system. We evaluated the influence of HHV-6 and HHV-7 infections on fibromyalgia (FM) clinical course. Forty-three FM patients and 50 control group participants were enrolled. 39.50% (n = 17) FM patients had light A delta and C nerve fiber damage, 27.91% (n = 12) had severe A delta and C nerve fiber damage. 67.44% (n = 29) FM patients had loss of warm sensation in feet, loss of heat pain sensation, and increased cold pain sensation (34.90%, n = 15 in both findings). HHV-6 and HHV-7 genomic sequences in peripheral blood DNA in 23/43 (51.00%) and 34/43 (75.50%) of samples from FM patients and in 3/50 (6.00%) and 26/50 (52.00%) of samples from the control group individuals were detected. Active HHV-6 (plasma viremia) or HHV-7 infection was revealed only in FM patients (4/23, 17.40% and 4/34, 11.80%, respectively). A statistically significant moderate positive correlation was found between A delta and C nerve fiber damage severity and HHV-6 infection (p < 0.01, r = 0.410). 23/43 patients from the FM group and control group participants HHV-6 and 34/45 HHV-7 did have infection markers. A statistically significant moderate positive correlation was found between A delta and C nerve fiber damage severity and HHV-6 infection (p < 0.01, r = 0.410). No difference was found between detection frequency of persistent HHV-6 and HHV-7 infection between FM patients and the control group. Statistically significant correlation was observed between quantitation of changes in QST thermal modalities and HHV-6 infection. There was no correlation between A delta and C nerve fiber damage and HHV-7 infection.

Cytomegalovirus and Other β-Herpesviruses

Cytomegalovirus (CMV), human herpes virus (HHV)-6, and HHV-7 are ubiquitous β-herpesviruses that can cause opportunistic infection and disease in kidney transplant recipients. Active CMV infection and disease are associated with acute allograft failure and death, and HHV-6 and HHV-7 replication are associated with CMV disease. CMV prevention strategies are used commonly after kidney transplantation, and include prophylaxis with antiviral medications and preemptive treatment upon the detection of asymptomatic viral replication in blood. Both approaches decrease CMV disease and allograft rejection, but CMV prophylaxis is preferred for high-risk patients because it is easy to administer and may be more effective in real-world settings. CMV disease commonly occurs even with current preventive strategies, whereas HHV-6 and HHV-7 diseases are rare. The clinical manifestations of CMV, HHV-6, and HHV-7 are nonspecific, and laboratory confirmation is essential to establishing diagnoses. Although nucleic acid testing has supplanted other diagnostic modalities given its high sensitivity and specificity, histopathologic examination sometimes is necessary to identify disease definitively. Ganciclovir and valganciclovir are the treatments of choice for CMV and HHV-6, and foscarnet can be used to treat HHV-7. Treatment duration should be informed by the initial severity of disease, and subsequent clinical and virologic responses.

Anti-herpesviral effects of a novel broad range anti-microbial quaternary ammonium silane, K21

We have created a novel quaternary ammonium silane, K21 through sol-gel chemistry, using an ethoxylated version of an organosilane quaternary ammonium compound and TetraEthyl Ortho Silicate (TEOS) as precursors. Previous studies using the precursor molecule quaternary ammonium compounds (QACs) and a methacryloxy version of K21, primarily designed for use in dental healthcare, have shown inhibited growth properties against several types of gram-positive and gram-negative bacteria including Escherichia coli, Streptococcus mutans, Actinomyces naeslundii and Candida albicans etc. Here we tested the effect of K21 on HSV-1, HHV-6A and HHV-7 in in vitro cell culture infection models. Our results show growth inhibitory effect of K21 on HSV-1, HHV-6A and HHV-7 infection.

Detection frequency of human herpesviruses-6A, -6B, and -7 genomic sequences in central nervous system DNA samples from post-mortem individuals with unspecified encephalopathy

In this autopsy-based study, human herpesvirus-6 (HHV-6) and -7 (HHV-7) genomic sequence frequency, HHV-6 variants, HHV-6 load and the expression of HHV-6 antigens in brain samples from the individuals, with and without unspecified encephalopathy (controls), using nested and real-time polymerase chain reactions, restriction endonuclease, and immunohistochemical analysis were examined. GraphPad Prism 6.0 Mann-Whitney nonparametric and chi-square test and Fisher's exact test were used for statistical analysis. The encephalopathy diagnoses were shown by magnetic resonance imaging made during their lifetime and macro- and microscopically studied autopsy tissue materials. Widespread HHV-6 and/or HHV-7 positivity was detected in the brain tissue of various individuals with encephalopathy, as well as in controls (51/57, 89.4 % and 35/51, 68.6 %, respectively; p = 0.009). Significantly higher detection frequency of single HHV-6 and concurrent HHV-6 + HHV-7 DNA was found in pia mater meninges, frontal lobe, temporal lobe, and olfactory tract DNAs in individuals with encephalopathy compared to the control group. HHV-6 load and higher frequency of the viral load >10 copies/10(6) cells significantly differed in samples from individuals with and without encephalopathy. The expression of HHV-6 antigens was revealed in different neural cell types with strong predominance in the encephalopathy group. In all HHV-6-positive autopsy samples of individuals with and without encephalopathy, HHV-6B was revealed. Significantly higher detection frequency of beta-herpesvirus DNA, more often detected HHV-6 load >10 copies/10(6) cells, as well as the expression of HHV-6 antigens in different brain tissue samples from individuals with encephalopathy in comparison with control group indicate on potential involvement of these viruses in encephalopathy development.

Human Herpesviruses as Copathogens of HIV Infection, Their Role in HIV Transmission, and Disease Progression

Of eight human herpesviruses (HHVs), often, only herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) find mention in medical literature as both of these viruses are commonly associated with genital lesions and oral ulcers, commonly known as cold sores. However, role of human herpesviruses as copathogens and in aggravation and in the transmission of other human diseases, especially the Acquired immunodeficiency syndrome (HIV/AIDS) has only very recently been recognized. Therefore, screening and treating subclinical HHV infections may offer slowing of HIV infection, disease progression, and its transmission. Beside HSV-1 and HSV-2, HHV-3 a causative agent of herpes zoster remained one of the first manifestations of HIV disease before the era of highly active antiretroviral therapy (HAART). HHV-5 also known as human Cytomegalovirus infection remains a significant risk factor for HIV-associated mortality and morbidity even in HAART era. It is proposed that Cytomegalovirus viremia could be a better predictor of HIV disease progression than CD4+ T-lymphocyte count. The role of HHV-4 or Epstein-Burr virus and HHV-6, HHV-7, and HHV-8 is still being investigated in HIV disease progression. This review provides insight into the current understanding about these 8 HHVs, their co-pathogenesis, and role in HIV/AIDS disease progression. The review also covers recent literature in favor and against administering anti-HHV treatment along with HAART for slower AIDS progression and interrupted sexual transmission.

Reactivation of Human Herpes Virus-6 After Pediatric Stem Cell Transplantation: Risk Factors, Onset, Clinical Symptoms and Association With Severity of Acute Graft-Versus-Host Disease

BACKGROUND AND METHODS

To study clinical symptoms, timing and consequences of human herpesvirus-6 (HHV-6) reactivation after pediatric allogeneic stem cell transplantation (SCT), HHV-6 was investigated by plasma polymerase chain reaction in a cohort of 106 pediatric SCT recipients.

RESULTS

HHV-6 viremia was detected post-SCT in 48% of the patients with a median time of onset at 20 days after SCT. In week 3 and 4 post-SCT, HHV-6 is the most common infectious agent detected. In up to 30% of the patients with fever of unknown origin, HHV-6 was the only detected infectious agent to explain fever. Patients transplanted with an unrelated donor or receiving serotherapy were at increased risk of HHV-6 reactivation. The onset of HHV-6 reactivation coincided with the appearance of lymphocytes and monocytes in peripheral blood. Treatment with alemtuzumab (MabCampath) delayed both lymphocyte and monocyte engraftment and, concomitantly, onset of HHV-6 reactivation was delayed in those cases. HHV-6 reactivation was not associated with an increased incidence of acute graft-versus-host disease (GvHD). However, progression to grade II-IV GvHD was in 9 of 10 patients associated with HHV-6 reactivation before GvHD (P = 0.006) and HHV-6 was the only infection with such an association.

CONCLUSIONS

HHV-6 frequently reactivates after pediatric SCT around the time of mononuclear cell engraftment and is associated with an increased severity of GvHD. HHV-6 may explain fever of unknown origin in 30% of the patients early after SCT. Assessment of HHV-6 reactivation in patients early after SCT can be instrumental for clinical decision making.

Delayed primary HHV-7 infection and neurologic disease

BACKGROUND

Primary human herpesvirus 7 (HHV-7) infection occurs almost universally during the first 5 years of life and is rarely accompanied by central nervous system (CNS) symptoms such as febrile seizures. The present retrospective study investigated the role of primary HHV-7 infection in CNS disease in children, including adolescents.

METHODS

The study included all children who had neurologic disease aged younger than 18 years seen at the Hospital for Sick Children, Toronto, Canada, between April 1, 1998 and December 31, 2011, whose cerebrospinal fluid (CSF) was found by polymerase chain reaction to contain HHV-7 DNA. Where sera were available, HHV-7 IgG antibody titers and avidity were measured to differentiate primary from past infection.

RESULTS

HHV-7 DNA was detected in the CSF of 57 (1.9%) of the 2972 children tested. In 3 adolescents primary HHV-7 infection (low avidity IgG) was confirmed as the cause of neurologic disease, 2 who had encephalitis and 1 who had Guillain-Barré syndrome. Eighteen children had possible HHV-7 disease (no alternative cause identified and indeterminate antibody result or serum not available), 7 encephalitis, 8 meningitis, and 3 demyelinating disorders. HHV-7 disease was excluded in 36 children on the basis of past infection (high IgG avidity) and/or an alternative cause.

CONCLUSIONS

Primary HHV-7 infection delayed into adolescence can cause serious neurologic disease. HHV-7 DNA in CSF alone is insufficient to prove an etiologic association. Combining CSF polymerase chain reaction with serology is essential to prove primary infection when investigating HHV-7 CNS disease.

Novel gene therapy viral vector using non-oncogenic lymphotropic herpesvirus

Despite the use of retroviral vectors, efficiently introducing target genes into immunocytes such as T cells is difficult. In addition, retroviral vectors carry risks associated with the oncogenicity of the native virus and the potential for introducing malignancy in recipients due to genetic carryover from immortalized cells used during vector production. To address these issues, we have established a new virus vector that is based on human herpesvirus 6 (HHV-6), a non-oncogenic lymphotropic herpesvirus that infects CD4⁺ T cells, macrophages, and dendritic cells. In the present study, we have altered the cell specificity of the resulting recombinant HHV-6 by knocking out the U2–U8 genes. The resulting virus proliferated only in activated cord blood cells and not in peripheral blood cells. Umbilical cord blood cells produced replication-defective recombinant virus in sufficiently high titer to omit the use of immortalized cells during vector production. HHV-6 vectors led to high rates (>90%) of gene transduction in both CD4⁺ and CD8⁺ T cells. These viruses showed low-level replication of viral DNA that supported greater expression of the induced genes than that of other methods but that was insufficient to support the production of replication-competent virus. Furthermore, HHV-6 vectors containing short hairpin RNAs against CD4 and HIV Gag remarkably inhibited the production of these proteins and HIV particles. Here we demonstrate the utility of HHV-6 as a new non-carcinogenic viral vector for immunologic diseases and immunotherapy.

Association of active human herpesvirus-6, -7 and parvovirus b19 infection with clinical outcomes in patients with myalgic encephalomyelitis/chronic fatigue syndrome

Frequency of active human herpesvirus-6, -7 (HHV-6, HHV-7) and parvovirus B19 (B19) infection/coinfection and its association with clinical course of ME/CFS was evaluated. 108 ME/CFS patients and 90 practically healthy persons were enrolled in the study. Viral genomic sequences were detected by PCR, virus-specific antibodies and cytokine levels-by ELISA, HHV-6 variants-by restriction analysis. Active viral infection including concurrent infection was found in 64.8% (70/108) of patients and in 13.3% (12/90) of practically healthy persons. Increase in peripheral blood leukocyte DNA HHV-6 load as well as in proinflammatory cytokines' levels was detected in patients during active viral infection. Definite relationship was observed between active betaherpesvirus infection and subfebrility, lymphadenopathy and malaise after exertion, and between active B19 infection and multijoint pain. Neuropsychological disturbances were detected in all patients. The manifestation of symptoms was of more frequent occurrence in patients with concurrent infection. The high rate of active HHV-6, HHV-7 and B19 infection/coinfection with the simultaneous increase in plasma proinflammatory cytokines' level as well as the association between active viral infection and distinctive types of clinical symptoms shows necessity of simultaneous study of these viral infections for identification of possible subsets of ME/CFS.

Hematopoietic cell transplantation and emerging viral infections

Viral infections remain important causes of morbidity and mortality in hematopoietic cell transplant recipients. More recent developments in preparative regimens and graft manipulations, as well as the control of well-recognized post-transplant infections by the introduction of prophylaxis and preemptive strategies, have influenced the timing and the epidemiology of infections. As new pathogens, such as human metapneumovirus (HMPV), human bocavirus, human coronaviruses HCoV-NL63 and HCoV-HKU1, human herpesviruses HHV-6 and HHV-7, and polyomaviruses, have emerged, it is fundamental to determine the significance of the newly discovered viruses and their role in the transplantation field. This article summarizes recent data on epidemiology and laboratory diagnosis of new pathogens, as well as clinical features and management of the associated infectious complications. J. Med. Virol. 82:528-538, 2010. (c) 2010 Wiley-Liss, Inc.

Chronic fatigue syndrome: inflammation, immune function, and neuroendocrine interactions

Investigations into the underlying cause of chronic fatigue syndrome have advanced the field considerably in the past year. Gene microarray data have led to a better understanding of pathogenesis. Recent research has evaluated genetic signatures, described biologic subgroups, and suggested potential targeted treatments. Acute viral infection studies found that initial infection severity was the single best predictor of persistent fatigue. Genomic studies showed that persistent cases express Epstein Barr virus-specific genes and demonstrate abnormalities of mitochondrial function. Studies of immune dysfunction extended observations of natural killer cytotoxic cell dysfunction of the cytotoxic T cell through quantitative evaluation of intracellular perforins and granzymes. Other research has focused on a subgroup of patients with reactivated viral infection. These advances should result in targeted therapies that impact immune function, hypothalamic-pituitary-adrenal axis regulation, and persistent viral reactivation.

Human herpesvirus 7 infection increases the expression levels of CD46 and CD59 in target cells

CD46 (membrane cofactor protein; MCP) is a molecule that functions as either a complement-regulatory protein (CRP) or a receptor for some pathogens, including human herpesvirus 6. DNA microarray analysis suggested that the expression of CD46 was upregulated in T cells infected with human herpesvirus 7 (HHV-7). Northen and Western blot analyses supported this result at both the transcriptional and translational levels. Flow-cytometric analysis revealed that upregulation of CD46 occurred at a late stage of infection in both SupT1 cells and primary CD4+ T cells, and also that expression of another CRP, CD59, was increased at a late stage of infection. Whether these CRPs actually function in HHV-7-infected cells was addressed and it was found that HHV-7-infected cells were more resistant to complement-dependent cytotoxicity than were uninfected cells. This study is the first report demonstrating that HHV-7 infection causes elevation of the CRPs CD46 and CD59, which may be a possible mechanism for HHV-7 to evade humoral immunity via complement.

Questionable role of human herpesviruses in the pathogenesis of Kikuchi disease

CONTEXT

Kikuchi disease is a self-limiting febrile lymphadenopathy characterized by a patchy area of apoptosis. Kikuchi disease is thought to be caused by a virus, but this has not been clearly demonstrated. Human herpesviruses 6 and 7 (HHV-6 and HHV-7) are lymphotropic viruses that can induce apoptosis in infected lymphocytes. Recently, HHV-8 was reported to be a possible etiologic agent of Kikuchi disease.

OBJECTIVE

To investigate the incidence of HHV-6, HHV-7, and HHV-8 infection in patients with Kikuchi disease.

DESIGN

Seventy archival tissue specimens (from 50 Kikuchi disease cases and 20 control cases) were tested for the presence of HHV-6 and HHV-7 using a nested polymerase chain reaction, and for the presence of HHV-8 using single-step polymerase chain reaction. Immunohistochemistry for HHV-8 expression was carried out in those cases in which HHV-8 was detected using polymerase chain reaction.

RESULTS

Of the 50 cases with Kikuchi disease, 21 (42%) were HHV-6 positive and 32 (64%) were HHV-7 positive. Eight (40%) of the 20 control cases were HHV-6 positive and 9 (45%) were HHV-7 positive. Both HHV-6 and HHV-7 were detected in 15 (30%) of the cases with Kikuchi disease and in 3 (15%) of the control cases. Three (6%) of the 50 cases of Kikuchi disease were HHV-8 positive but revealed no positive cells on immunohistochemical analysis for HHV-8. Human herpesvirus 8 was not expressed in any of the control cases.

CONCLUSIONS

There was no association between the presence of HHV-6 or HHV-7 and Kikuchi disease. Because the HHV-8 genome but not protein was detected in a small proportion of the cases of Kikuchi disease, its potential causative role in this disease should be determined by further studies.

Drug-Induced Hypersensitivity Syndrome due to Mexiletine Hydrochloride Associated with Reactivation of Human Herpesvirus 7

It has been suggested that reactivation of human herpesvirus 6 (HHV-6) infection may be involved in the pathogenesis of drug-induced hypersensitivity syndrome. We report a 45-year-old Japanese man who developed a generalized papuloerythematous rash, fever, hepatitis, lymphadenopathy and lymphocytosis with an increased number of atypical lymphocytes. He was diagnosed with DIHS due to mexiletine hydrochloride based on laboratory data, results of a patch test and the clinical course of his complaint, and was treated with systemic steroids. In order to determine whether HHV-6 or -7 was associated with the patient's disease, serological assays and PCR were carried out. Significant increases in antibody titers against HHV-6 and -7 were observed from day 12 to 24. From PCR analysis, none of the peripheral blood mononuclear cells or skin tissue samples contained HHV-6 DNA. All samples, however, were found to contain HHV-7 DNA. Reactivation of HHV-7 could be responsible for drug-induced hypersensitivity syndrome.

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

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

Human herpesvirus 6 and multiple sclerosis: a one-year follow-up study

BACKGROUND

This study was undertaken in order to investigate the possible relation of HHV-6 and EBV in relapsing-remitting MS (RRMS).

MATERIALS AND METHODS

A one-year follow up study was performed analysing peripheral blood mononuclear cells and serum samples of 57 patients with RRMS and 57 healthy blood donors (HBD) by a quantitative real time PCR, to detect HHV-6 and EBV. Clinical data (starting age and EDSS increase) were collected.

RESULTS

We did not find any statistically significant difference for EBV between RRMS patients and HBD. Regarding HHV-6: i) There was a higher prevalence of HHV-6 in RRMS patients than in controls: 80.7% versus 29.8% respectively. ii) HHV-6 active replication seems to be related to exacerbations. iii) Only variant A was detected among RRMS patients with HHV-6 active replication. iv) Although some difference was found when we compared clinical data in RRMS patients with and without HHV-6 active replication, the results did not reach statistical significance.

CONCLUSIONS

A higher HHV-6A frequency of active infection (reactivation or new infection) would lead to a more frequent exposure of HHV-6A antigens to the immune system of RRMS patients; this active replication of HHV-6A seems to be specifically related with the exacerbations in a subset of RRMS patients.

Latent infection of human herpesvirus 7 in CD4(+) T lymphocytes

To determine the cell populations in peripheral blood that are infected latently with human herpesvirus 7 (HHV-7), the real-time polymerase chain reaction (PCR) was used to determine the quantities of viral DNA in adherent and non-adherent cells from 71 healthy volunteers. Real-time PCR, which detected the U31 gene of HHV-7, was developed to measure viral load. The majority of non-adherent cells (14/16; 87.5%) contained HHV-7 DNA, while most of the adherent cells did not (1/16; 6.3%). HHV-7 viral load in non-adherent cells was significantly higher than that in adherent cells (P < 0.0001). Then, HHV-7 DNA load was compared between the CD4-positive and -negative cell fractions derived from the non-adherent cells of 26 healthy adults. As in the previous experiment, only 2 (7.7%) of the 26 adherent cell specimens contained small amounts of HHV-7 DNA (27.7 copies/1 x 10(6) cells and 208.7 copies/1 x 10(6) cells). In contrast, 88.5% of CD4(+) T cell samples (23/26 specimens) were positive for HHV-7 DNA, ranging from 0.4 to 3,542.8 copies/1 x 10(6) cells. Viral DNA was detected in only 3 (11.5%) of the 26 CD4(-) T cell specimens, with 8.4, 63.5, and 74.1 copies/1 x 10(6) cells. HHV-7-positive DNA loads were significantly higher in the CD4(+) T cells than those observed in the CD4(-) T cells (P = 0.0005). The relationship between HHV-7 viral loads in non-adherent cells and those in saliva was investigated. Comparison of HHV-7 DNA load between blood CD4(+) T cells and saliva revealed that the HHV-7 DNA load in saliva correlated with that present in CD4(+) T cells (r = 0.415; P = 0.0174).

Comparison of the SYBR Green and the hybridization probe format for real-time PCR detection of HHV-6

A comparative study was conducted of a novel real-time quantitative PCR test (LightCycler System) with FastStart DNA Master(PLUS) SYBR Green I dye to detect DNA of human herpes virus 6 (HHV-6). Results were compared with those of a real-time quantitative PCR with hybridization probe (HP) formats using the fluorescence resonance energy transfer method, and with those of a single qualitative PCR test. The detection limit of the test with SYBR Green I dye was 20 copies of the virus, similar to that of the other two tests. The reproducibility was satisfactory. The new test has the same advantages as real-time PCR with HP formats and offers a greater versatility at lower cost.

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

BACKGROUND

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

PROCEDURE

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

RESULTS

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

CONCLUSIONS

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

Drug-Induced Hypersensitivity Syndrome due to Carbamazepine Associated with Reactivation of Human Herpesvirus 7

We report a 63-year-old Japanese man with epilepsy who developed skin eruptions, liver dysfunction, high fever, leukocytosis and atypical lymphocytosis 4 weeks after he had started taking carbamazepine. Titers of human herpesvirus 7 (HHV-7)-specific IgG antibodies were significantly increased and HHV-7 DNA was detected in his serum by polymerase chain reaction. These findings suggested that reactivation of HHV-7 could contribute to the development of drug-induced hypersensitivity syndrome.

Human herpesvirus 7 open reading frames U12 and U51 encode functional beta-chemokine receptors

Human herpesvirus 7 (HHV-7), which belongs to the betaherpesvirus subfamily and infects mainly CD4+ T cells in vitro, infects children during infancy. HHV-7 contains two genes, U12 and U51, that encode putative homologs of cellular G-protein-coupled receptors. To analyze the biological function of the U12 and U51 genes, we cloned these genes and expressed the proteins in cells. U12 and U51 encoded functional calcium-mobilizing receptors for beta-chemokines, which include thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), EBI1-ligand chemokine (ELC), and secondary lymphoid-tissue chemokine (SLC), but not for other chemokines, suggesting that the chemokine selectivities of the U12 and U51 products were distinct from those of the known mammalian chemokine receptors. ELC and SLC induced migration in Jurkat cells stably expressing U12, but TARC and MDC did not. In contrast, none of these chemokines induced migration in Jurkat cells stably expressing U51. Together, these data indicate that the products of U12 and U51 may play important and different roles in the pathogenesis of HHV-7 through transmembrane signaling.

Detection of human herpesvirus 7 DNA in peripheral blood reflects mainly CD4+ cell count in patients infected with HIV

The opportunistic behavior and the potential interactions of human herpesvirus 7 (HHV-7) with human immunodeficiency virus (HIV)-1 in HIV-1-infected patients were investigated in comparison with HHV-6, another human roseolovirus. Roseolovirus DNAs were detected and quantified in peripheral blood mononuclear cells (PBMCs) from 198 HIV-seronegative healthy blood donors, 38 HIV-1-infected patients classified as long-term non-progressors, and 99 HIV-1-infected patients classified as progressors. The rate of HHV-7 DNA detection was higher in healthy donors (78%) than in long-term non-progressors (47%; P = 0.0003) or in progressors (52%; P < 0.0001). HHV-7 cell load was higher in healthy donors (median: 212 EqCop/10(6) PBMCs) and in long-term non-progressors (median: 105 EqCop/10(6) PBMCs) than in progressors (median: 48 EqCop/10(6) PBMCs; P < 0.0001 and P = 0.015, respectively). Among progressors, HHV-7 detection was correlated positively with the CD4(+) T-lymphocyte count (P = 0.028). Neither HHV-7 detection rate nor cell load was correlated with the HIV-1 plasma load. As a whole, HHV-6 detection rate and cell load were lower than the HHV-7 counterparts, albeit exhibiting similar differences between healthy donors, long-term non-progressors, and progressors. In conclusion, HHV-7 infection does not appear to be stimulated by HIV-1 infection, nor interact with it. Rather, HHV-7 detection rate and cell load reflect CD4(+) T-lymphocyte count, with higher values in healthy donors and long-term non-progressors than in progressors.

Human herpesviruses 6 and 7 and central nervous system infection in children

Human herpesviruses 6 and 7 were infrequently found in cerebrospinal fluid of children with central nervous system infection.

The role and frequency of human herpesviruses (HHV)-6 and -7 in central nervous system (CNS) diseases of children are unclear. Cerebrospinal fluid samples from 245 pediatric patients (median age 43 days), submitted for evaluations of possible sepsis or of neurologic symptoms, were tested for HHV-6 and HHV-7 DNA by polymerase chain reaction. HHV-6 DNA was found in 3 of 245 samples, and HHV-7 was found in 0 of 245 samples. The three patients with HHV-6 DNA were <2 months of age. HHV-6 was likely pathogenic in two patients with meningitis who lacked evidence of another microbiologic cause. HHV-6 and HHV-7 are uncommon causes of CNS infection in children. HHV-6 may occasionally cause meningitis in young infants.

Lytic replication-defective Kaposi's sarcoma-associated herpesvirus: potential role in infection and malignant transformation

Defective viruses often have pivotal roles in virus-induced diseases. Although Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically associated with Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL), defective KSHV has not been reported. Using differential genetic screening methods, we show that defective KSHV is present in KS tumors and PEL cell lines. To investigate the role of defective viruses in KSHV-induced pathogenesis, we isolated and characterized a lytic replication-defective KSHV, KV-1, containing an 82-kb genomic deletion of solely lytic genes. Cells harboring KV-1 escaped G(0)/G(1) apoptosis induced by spontaneous lytic replication occurred in cells infected with regular KSHV but maintained efficient latent replication. Consequently, KV-1-infected cells had phenotypes of enhanced cell proliferation and transformation potentials. Importantly, KV-1 was packaged as infectious virions by using regular KSHV as helpers, and KV-1-like variants were detected in cultures of two of five KSHV cell lines and 1 of 18 KS tumors. These results point to a potential role for defective viruses in the regulation of KSHV infection and malignant transformation.

Human herpesvirus-7 as a cause of exanthematous ilnesses in Belém, Pará, Brazil

We screened sera from 370 patients suffering from exanthematous illnesses in Belém, North Brazil, for the presence of human herpesvirus-7 (HHV-7) IgM and IgG antibodies. Samples were obtained from January 1996 to December 2002 and were processed by a HHV-7-specific indirect immunofluorescence assay (IFA). HHV-7-specific IgM and/or IgG antibodies were found in 190 (51.4%) of these patients, with similar prevalence rates (IgM+ and IgG+ subgroups taken together) for female and male subjects: 52.5% and 50.3%, respectively. Serological status as defined by IgG was identified in 135 (36.5%) patients. In 55 (14.9%) of the patients HHV-7 IgM antibodies were detected. HHV-7 IgM- and- IgG antibody rates were similar (p > 0.05) when male and female subjects are compared: 14.4% versus 15.3% and 38.1% versus 35.0%, respectively. Statistically significant difference (p = 0.003) was noted when HHV-7-IgM-positive female and male patients aged 5-8 months are compared. Prevalence rates ranging from 4.6% (female, 5-8 months of age) to 93.3% (female, > 10 years of age) and 12.2% (male, 5-8 months) to 80.0% (male, 8-10 years of age) were noted in the IgG- positive subgroups. A subgroup (n = 131) of patients with IgM or IgG HHV-7 antibodies were examined for the presence of DNA using a polymerase chain reaction/nested PCR. Recent/active HHV-7 infection occurred at a rate of 11.0% (6/55) among patients whose samples presented IgM+ specific antibodies. In a subgroup (n = 76) of patients with high HHV-7-IgG antibody levels (titre > 1:160) DNA could not be detected in sera examined by PCR/nested PCR. Of the six recent/active infections, four subjects with less than 1 year and two with 3 and 6 years of age, presented typical exanthem subitum (E.S), as defined by higher fever (> 38.0 ºC) with duration of 24 to 72 hours, followed by a maculopapular skin rash. Our results underscore the need for searching HHV-7 infection in patients with exanthematous diseases, particularly those presenting with typical E.S. HHV-7 appears therefore to emerge as a newly recognized pathogen of exanthem in our region.

Detection of human herpesvirus 7 DNA by loop-mediated isothermal amplification

The reliability of loop-mediated isothermal amplification (LAMP), initially developed for the detection of human herpesvirus 7 (HHV-7), was evaluated in this study. Although a LAMP product was detected in HHV-7 DNA, neither HHV-6 nor human cytomegalovirus DNA produced a product. When agarose gel electrophoresis was used for the detection of LAMP products, the sensitivity of a 30-min HHV-7 LAMP reaction reached 250 copies/tube. The use of turbidity for the detection of the LAMP products gave a sensitivity of 500 and 250 copies/tube for 30- and 60-min reactions, respectively. Following these initial validation studies, clinical samples collected from two patients with primary HHV-7 infections were examined by HHV-7 LAMP. By use of agarose gel electrophoresis, HHV-7 LAMP products could be detected in acute-phase plasma samples but no LAMP product was detectable in convalescent-phase plasma samples from either patient. Since a turbidity assay is less sensitive than agarose gel electrophoresis, no HHV-7 LAMP product could be detected in plasma samples after a 30-min LAMP reaction. After a 60-min LAMP reaction, HHV-7 LAMP product could be detected in acute-phase plasma samples.

HHV-6 and 7 DNA loads in lung tissues collected from patients with interstitial pneumonia

The aim of this study is to determine whether human herpesvirus 6 (HHV-6) and HHV-7 might play an important role in causing interstitial pneumonia in patients who have not undergone transplantation. HHV-6 and HHV-7 DNAs were quantitated by real-time polymerase chain reaction (PCR) in paraffin embedded lung tissues collected from 24 patients having the disease. Control tissues (without fibrosis) were also collected from 19 of the 24 patients. Statistical analysis was carried out by the Wilcoxon signed rank test or the Mann-Whitney U-test. HHV-6 DNA was detected in 3 (12.5%) of the 24 target tissues and 3 (15.8%) of the 19 control tissues, respectively. In contrast, HHV-7 DNA was detected in 19 (79.2%) of the 24 target tissues and 11 (57.9%) of the 19 control tissues. Neither HHV-6 DNA load (P = 0.6395) nor HHV-7 DNA load (P = 0.5966) in target tissues differed between males and females. Neither HHV-6 DNA load (P = 0.9589) nor HHV-7 DNA load (P = 0.7419) in target tissues differed between cases with and without underlying collagen disease. While HHV-6 DNA load did not differ between the target and control tissues (P > 0.9999), the HHV-7 DNA load was significantly higher in the target tissue than in the control tissue (P = 0.0298). This study suggests that HHV-7 may play an important role in causing interstitial pneumonia in patients who are not transplant recipients.

Tissue HHV6 and 7 determination in pediatric solid organ recipients--a pilot study

Herpes virus infections remain a major challenge in solid organ transplantation. HHV6 and 7 blood viral load was associated with pathology after renal transplantation. Little is known about the significance of tissue HHV6 and 7 infections. A total of 18 tissue biopsies (13 kidney, three GI and two BAL) from nine pediatric transplant patients (five kidney, two liver, one combined liver and kidney and one bone marrow transplant) were subjected to blood HHV6 IgG and IgM testing. In addition, tissue HHV6 and 7 semi-quantitative PCR analysis with subsequent detection by ELISA and quantitative methods were applied to the same samples. We also studied four native kidney biopsies of children with other kidney disease. The results of the biopsies were correlated with clinical data. Of the transplant patients, 78% were HHV6 IgG positive. Six of nine had a positive IgM on at least one occasion, however, only two of nine transplant patients were symptomatic with a mixed CMV/EBV septic picture of multi-organ failure. Only these two patients had a significant tissue viral load for HHV6. Additionally, a very significant tissue viral load for HHV6 was detected in an immunocompromised patient 3 wk after a roseola-like febrile illness. The HHV6 copies were 31, 88 and 206 per 10 microL of DNA, respectively. In the patient who also had the fourth positive ELISA for HHV6 PCR product, the Multiplex PCR and restriction enzyme assay on its PCR product revealed a significant contribution by HHV7, while the HHV6-B signal was rather weak. Significant tissue HHV6 loads can be found in tissue biopsies from organ recipients with significant illness and also in native kidneys after primary infection. This may explain the high prevalence of HHV6 in transplanted kidneys. Further studies on HHV6 and 7 using molecular techniques should be supported.