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.

Reactivation of human herpesviruses 6 and 7 in Kawasaki disease.

Objectives: Kawasaki disease (KD) is one of the most common childhood vasculitides. Some serological studies have suggested an etiological relationship between KD and human herpesvirus (HHV)-6 or HHV-7. However, primary or reactivated HHV-6 and -7 has not been fully investigated in patients with KD. Methods: Twenty-three patients with KD were prospectively enrolled in this study. Peripheral blood was collected in the acute and convalescence phases, and HHV-6 and -7 viral loads were measured by real-time PCR. Results: In the acute phase, HHV-6 and -7 DNA was detected in 7 (30%) patients each, compared to 13 (57%) and 9 (39%) patients in the convalescence phase, respectively. HHV-6 and -7 DNA loads were significantly higher in the convalescence phase than in the acute phase. Significant increases in HHV-6 and -7 DNA loads were not observed in disease control patients. Taking into account HHV-6 and -7 serostatus, reactivation of HHV-6 and -7 was observed in 7 and 9 patients, respectively. KD patients with HHV-6 reactivation showed higher C-reactive protein levels and more frequently required steroid therapies than patients without reactivation. Conclusion: HHV-6 and -7 reactivation is frequent in KD patients. HHV-6 reactivation might exacerbate the severity of KD.

Summary of the 10th International Conference on Human Herpesviruses-6 and -7 (HHV-6A, -6B, and HHV-7).

The 10th International Conference on Human herpesviruses-6 and -7 (HHV-6A, HHV-6B, and HHV-7) was held at the Freie Universität, Berlin, Germany from July 23-26, 2017. It attracted more than 130 basic, translational and clinical scientists from 19 countries. Important new information was presented regarding: the biology of HHV-6A and -6B; the biology and epidemiology of inherited chromosomally integrated HHV-6A and -6B; improved diagnostic tests; animal models for and animal viruses with similarities to HHV-6A, -6B, and -7; established and possible disease associations; and new treatment strategies. Here, we summarize work presented at the meeting that is of particular interest.

Possible chromosomal and germline integration of human herpesvirus 7.

Human herpesvirus 7 (HHV-7) is a betaherpesvirus, and is phylogenetically related to both HHV-6A and HHV-6B. The presence of telomeric repeat sequences at both ends of its genome should make it equally likely to integrate into the human telomere as HHV-6. However, numerous studies have failed to detect germline integration of HHV-7, suggesting an important difference between the HHV-6A/-6B and HHV-7 genomes. In search of possible germline integrated HHV-7, we developed a sensitive and quantitative real-time PCR assay and discovered that primers designed against some parts of the HHV-7 genome can frequently miss HHV-7 positive clinical samples even though they work efficiently in cell-culture-derived HHV-7 positive materials. Using a primer pair against the U90 ORF of HHV-7, we identified a possible case of germline integration of HHV-7 with one copy of viral genome per cell in both peripheral blood cells and hair follicles. Chromosomal integration of HHV-7 in these individuals was confirmed by fluorescence in situ hybridization analysis. Germline integration of HHV-7 was further confirmed by detection of ~2.6 copies of HHV-7 in the hair follicles of one of the parents. Our results shed light on the complex nature of the HHV-7 genome in human-derived materials in comparison to cell-culture-derived materials and show the need for stringent criteria in the selection of primers for epidemiological HHV-7 studies.

Acute human herpes virus 7 (HHV-7) encephalitis in an immunocompetent adult patient: a case report and review of literature.

We report a case of an acute HHV-7 encephalitis involving the nucleus of the VI cranial nerve in an immunocompetent host. The patient was an adult male admitted to our Clinic with headache, diplopia, fever, nausea, vertigo, asthenia and general malaise. PCR for viral and bacterial genomes was run on both serum and cerebral spinal fluid (CSF) after performing lumbar puncture, resulting positive only for HHV-7 DNA on CSF. MRI showed hyperintensity in FLAIR signal in the dorsal pons, in the area of the VI cranial nerve nucleus. Empirical therapy with Acyclovir and Dexamethasone was started at the time of admission and was continued after the microbiology results. After three days of therapy diplopia, fever and other previous clinical manifestations improved and the patient recovered normal sight. Our case report contributes to a better understanding of the presentation, diagnosis and treatment of HHV-7 encephalitis in immunocompetent patients due to reactivation in adult age.

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

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

A fatal case of DRESS induced by strontium ranelate associated with HHV-7 reactivation.

We report the first case of drug rash with eosinophilia and systemic symptoms (DRESS) following strontium ranelate (SR) treatment associated with systemic human HHV-7 reactivation. DRESS syndrome is a severe adverse drug-induced reaction presenting as a diffuse maculopapular skin rash with fever, hematological abnormalities (leukocytosis, eosinophilia, and/or atypical lymphocytosis), and multiorgan involvement. In our patient, diagnosis of DRESS was confirmed by the presence of six of the seven diagnostic criteria established in 2006 by the Japanese Research Committee on Severe Cutaneous Adverse Drug Reaction: maculopapular skin rash developing at least 3 weeks after starting therapy with a limited number of drugs, prolonged clinical symptoms after discontinuation of the causative drug, lymphadenopathy, fever, leukocyte abnormalities, and liver abnormalities. The diagnostic criteria of human herpesvirus (HHV)-6 reactivation have not been fulfilled in our patient, but a HHV-7 active infection was demonstrated by the presence of HHV-7 DNA and IgM in the patient's serum. In fact, in some DRESS instances, reactivation of HHVs other than HHV-6 may be detected, including HHV-7, Epstein-Barr virus (EBV), and cytomegalovirus (CMV). Our case underlines that not only HHV-6 but also HHV-7 systemic reactivation may be associated with a more severe and even fatal course of this syndrome.

Did a then unknown virus, HHV-6/7, give rise to the whooping cough vaccine controversy of the 1970s?

During the 1970s there was a gross loss of public confidence in infant diphtheria-tetanus-pertussis (DTP) vaccination in the UK. As well as febrile reactions and convulsions, permanent neurological damage was ascribed to the pertussis component of the vaccine, and those concerns resonated worldwide. The subsequent recognition of human herpes virus 6 (HHV-6) and 7 (HHV-7) as common sources of fever in infancy suggests that they were the main underlying cause of what was reported as DTP constitutional side-effects. With more precise data on the incidence of HHV-6/7 and other virus infections in early life it would be possible to model the concurrence of viral illnesses with routine immunizations. Adventitious viral infections may be the cause of side-effects ascribed to the numerous childhood immunizations now being given.

Pityriasis rosea in a hepatitis B-positive patient treated with pegylated interferon α2a: report of a case and review of the literature.

Pityriasis rosea (PR) is an acute, self-limiting exanthematous disease caused by the endogenous reactivation of human herpesvirus (HHV)-6 and/or HHV-7 infection in conditions of altered immunity. In addition, many drugs have been incriminated as possible triggers of PR-like eruptions, characterized by clinical, morphological and histopathological features that differ from typical PR. Here, we report a case of PR in a patient with chronic hepatitis B, receiving pegylated interferon α2a (PEG-IFN-α2a). PR, arising after the second administration of the PEG-IFN-α2a, might be considered a clinical expression of the patient's altered immune condition as reported in the immune reconstitution inflammatory syndrome affecting patients with human immunodeficiency virus infection after high-dose antiretroviral therapy.

Kikuchi-Fujimoto disease: a case supporting a role for human herpesvirus 7 involvement in the pathogenesis.

Kikuchi's disease, also known as histiocytic necrotizing lymphadenitis, is a rare, benign, and self-limited disorder of unknown cause that is usually characterized by cervical lymphadenopathy and fever. The etiology and pathogenesis remain unknown, but the clinical presentation, course, and histologic changes suggest an immune response of T cells and histiocytes to an infectious agent. Numerous inciting agents have been proposed. However, the association between human herpesvirus 7 and Kikuchi's disease has been rarely reported as a possible etiologic agent of Kikuchi's disease. We report the case of a 24-year-old Caucasian female patient with cervical lymphadenopathy and isolated pruriginous maculo-papular lesions who was diagnosed of Kikuchi's disease in whom the presence of human herpesvirus 7 DNA was documented in the affected lymph node specimen in the absent of other viruses. Therefore, a possible etiologic relation between the Kikuchi's disease of this patient and human herpesvirus 7 was established, supporting a role for human herpesvirus 7 involvement in the pathogenesis.

Relationship between beta-herpesviruses reactivation and development of complications after autologous peripheral blood stem cell transplantation.

The relationship between beta-herpesviruses reactivation and the development of complications after autologous peripheral blood stem cell transplantation was investigated. Viral genomic sequences were detected by the polymerase chain reaction, virus-specific antibodies by ELISA, and human herpesvirus (HHV)-6 variants by restriction endonuclease analysis. Virus reactivation, serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6, soluble IL-2 receptor (sIL-2R), IL-2, and IL-4 were compared with clinical features in 44 patients before and after transplantation. Anti-CMV and anti-HHV-6 antibodies were found in 70.5% and 81.8% of patients, respectively. The frequency of plasma viremia was significantly higher in patients after transplantation (41% vs. 11.4%). Reactivation of more than one virus was identified in 55.6% of patients and reactivation of HHV-7 alone in 44.4%. In cases of concurrent infection, HHV-7 was reactivated before HHV-6, and both HHV-6 and HHV-7 were reactivated before CMV. There was a significant increase in HHV-6 load in peripheral blood leukocytes DNA during viremia. In all cases HHV-6B variant was detected. Complications after transplantation occurred in 27.3% of patients and virus reactivation was detected in all patients with complications. The significant increases in the rate of HHV-6 and HHV-7 reactivation and in serum levels of TNF-α, IL-1ß, and sIL-2R, as well as aggravated immunosuppression, suggest that both viruses were involved in the complications after autologous peripheral blood stem cell transplantation, via their immunomodulatory activity. The kinetics of reactivation suggests a potential role of HHV-7 as a co-factor of HHV-6 reactivation, and of both HHV-6 and HHV-7 as co-factors of CMV reactivation.

[Six cases of spring DRESS]. / Six cas de DRESS printaniers.

BACKGROUND: An association between herpes virus reactivations and Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) is accepted. We report six cases of DRESS with viral reactivation occurring within a single 1-month period. We attempted to find a common factor for these six cases and carried out clinical and virological examinations. Before and after this "epidemic", the mean number of cases of DRESS seen at the same centre was one per quarter, making the occurrence of six cases within a single month all the more remarkable and prompting us to seek an explanation. PATIENTS AND METHODS: All six patients had taken a partly causative medication from different drug classes three to six weeks prior to the start of symptoms and herpes virus was detected in the blood of all of these subjects at the time of DRESS onset (four reactivations and two primary infections), and one patient subsequently displayed herpetic meningoencephalitis 95 days after the initial episode, associated with recurrence of DRESS. DISCUSSION: There was no common denominator among these six DRESS patients in terms of either drug class or reactivation of a particular type of herpes virus, which raises the possibility of a single unidentified environmental agent. DRESS does not appear fully explainable in terms of a cellular response to drug antigens but seems rather to result from complex interactions between the drug-induced immune response, viral reactivation and antiviral immune response. Several investigators have reported sequential reactivation of herpes viruses in DRESS. A viral epidemic could thus cause a "DRESS epidemic" in patients on medication. CONCLUSION: These cases point to the possible existence of a shared initial environmental factor (infectious or not) that favours reactivation of herpes viruses and induces DRESS in patients on medication. Before and after this "DRESS epidemic", about one patient each quarter was admitted to hospital for DRESS.

Pityriasis Rosea after COVID-19 Infection.

Dear Editor, Pityriasis rosea (PR) is a common, self-limited erythematous papulosquamous dermatosis that mainly affects young adults. It is believed to represent a delayed reaction to viral infections and is usually associated with endogenous systemic reactivation of human herpesvirus (HHV) 6 and / or 7 (1). A 46-year-old man presented to our Department with a two-week history of skin rash associated with mild pruritus. He described the appearance of an erythematous centrally scaled lesion at the right part of his abdomen, followed by the spreading of red oval mildly scaling lesions on the trunk, neck, and proximal parts of the upper extremities, which showed in the physical examination (Figure 1, a and b). He was otherwise healthy and taking no medications. Six weeks prior to the appearance of the initial skin lesion, the patient had coronavirus disease 2019 (COVID-19) infection with mild clinical presentation (fever up to 38 °C lasting for four days and mild headache) and with symptoms of post COVID-19 syndrome (excessive tiredness). He denied oropharyngeal lesions. Potassium hydroxide, syphilis, and laboratory tests were within normal limits. Within two weeks of topical betamethasone dipropionate treatment, the lesions disappeared completely. In addition to reactivation of HHV-6 or HHV-7, PR can be triggered by some drugs (like angiotensin-converting enzyme inhibitors alone or in combination with hydrochlorothiazide, sartans plus hydrochlorothiazide, allopurinol, nimesulide, and acetyl salicylic acid (2) and vaccines (such as smallpox, poliomyelitis, influenza, human papillomavirus, diphtheria, tuberculosis, hepatitis B, pneumococcus, and yellow fever vaccines) (3). There is a growing number of published cases that link PR to COVID-19 infection, with PR appearing either in the acute phase of COVID-19 or, as in our patient, in the post COVID-19 period (4-9). Unlike in our patient, oropharyngeal lesions were observed in approximately 16% of patients with typical PR (10). It has been suggested that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces reactivation of other viruses, such as HHV-6, HHV-7, varicella zoster virus, and Epstein-Barr virus (5). PR has also been reported to follow COVID-19 vaccination (11). As our patient did not receive a COVID-19 vaccine, we cannot evaluate the latter based on the present case. We speculate that PR could be a delayed skin manifestation of COVID-19 infection, triggered either by SARS-CoV-2 immediately or indirectly by the reactivation of other viruses such as HHV-6 or HHV-7. However, the etiopathogenetic mechanisms remain largely unknown and further studies are needed in order to clarify the correlation between SARS-CoV-2 and PR.

Human herpesvirus 6 and 7 reactivation and disease activity in multiple sclerosis.

UNLABELLED: Recent studies have focused on the associations between human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7), and multiple sclerosis (MS). The aim of this study was to investigate the associations between HHV-6 and HHV-7 reactivation and MS disease activity, and interleukin 12 (IL-12) and tumor necrosis factor α (TNF-α) production. MATERIAL AND METHODS: The frequency of plasma viremia by nested polymerase chain reaction and transcription of viral mRNA in peripheral blood mononuclear cells by reverse transcriptase-polymerase chain reaction (RT-PCR) of 14 relapsing/remitting (RR) and 14 secondary progressive (SP) MS patients were studied in comparison with clinical manifestation of the disease. Serum concentrations of cytokines IL-12 and TNF-α were analyzed by enzyme-linked immunosorbent assay. RESULTS: Plasma samples from 25 of the 28 MS patients with estimated latent/persistent HHV-6 and/or HHV-7 infection were examined during relapse and remission/relative remission. HHV-6 reactivation was found in 4 of the 7 RRMS and 4 of the 7 SPMS patients, and HHV-7 reactivation was identified in 3 of the 7 RRMS and 1 of the 7 SPMS patients (all in relapse). In 2 of the 3 RRMS patients without viremia in relapse, HHV-6 mRNA transcription was detected. In RRMS and SPMS patients with active HHV-6 and HHV-7 infection in relapse, the serum concentrations of IL-12 and TNF-α were significantly higher than in those with latent virus infection. CONCLUSIONS: HHV-6 and HHV-7 reactivation could be implicated in the exacerbation of MS via activation of Th1 lymphocyte subsets.

Infection of gamma/delta T lymphocytes by human herpesvirus 6: transcriptional induction of CD4 and susceptibility to HIV infection.

Human herpesvirus 6 (HHV-6), a T-lymphotropic human herpesvirus, is a potentially immunosuppressive agent that has been suggested to play a role as a cofactor in the natural history of human immunodeficiency virus (HIV) infection. We studied the interactions between HHV-6 and gamma/delta T lymphocytes, a subset of T cells involved in the protective immune response against specific microorganisms. Polyclonal gamma/delta T cell populations, purified from the peripheral blood of healthy adults and activated in vitro with phytohemagglutinin, were exposed to HHV-6, strain GS (subgroup A), at the approximate multiplicity of infection (MOI) of 1. Signs of virus replication were detected as early as 72 h after infection, as documented by immunofluorescence, electron microscopy, and transmission of extracellular virus. Progression of the infection was associated with the appearance of typical cytomorphological changes and, eventually, massive cell death. In contrast, no signs of infection or cytopathic effects were detected after exposure of gamma/delta T lymphocytes to HHV-7, a CD4+ T-lymphotropic virus closely related to HHV-6. Polyclonal gamma/delta T cells displayed cytolytic activity against both autologous and heterologous target cells infected with HHV-6 and maintained this activity for at least 72 h after infection with HHV-6, despite the high MOI used. As previously documented in mature CD8+ alpha/beta T cells and natural killer cells, HHV-6 infection induced gamma/delta T lymphocytes to express de novo CD4 messenger RNA and protein, as detected by reverse transcriptase-polymerase chain reaction and fluorocytometry, respectively. Whereas purified CD4- gamma/delta T cell populations were per se refractory to HIV infection, they became susceptible to productive infection by HIV-1, strain IIIB, after induction of CD4 expression by HHV-6. These results demonstrate that gamma/delta T cells can be directly targeted and killed by a herpesvirus and may have implications for the potential role of HHV-6 in AIDS.

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

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

Human Herpesvirus 7-Related Acute Encephalopathy with Biphasic Seizures and Late Reduced Diffusion.

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a recently described entity so far exclusively in East Asian children. AESD diagnosis is based on clinicoradiologic criteria, often without pleocytic CSF and characterized by hyperglycemia and transaminasemia. Here, we present the first case of human herpesvirus 7-related AESD in an immunocompetent child >2 years old and of Caucasian origin.