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.

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 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.

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.

Relapsing Pityriasis Rosea With HHV-7 Reactivation in an 11-Year-Old Girl.

Pityriasis rosea (PR) usually presents as acute exanthema with oval erythematous-squamous lesions localized on the trunk, arms, and legs with spontaneous remission. We present an unusual case of PR with frequent relapses during a period of 7 years. An 11-year-old white female patient presented with many pruritic erythematous oval lesions on her trunk. A second episode followed 2 years later with several pruritic erythematous lesions on her lower limbs. During the following 5 years, the patient had several relapses per year, with 1 to 3 lesions on changing localizations. PR was diagnosed on the basis of the clinical presentation and detection of human herpesvirus 7 DNA. Spontaneous remission occurred without treatment in each episode. Relapsing PR is a rare form of PR characterized by a lower number of lesions and smaller sized lesions compared with the classic form of PR. Pediatricians should consider the diagnosis of relapsing PR even if only a single or few erythematous lesions are present.

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.

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.

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.

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.

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.

Analysis of the shedding of three ß-herpesviruses DNA in Polish patients subjected to allogeneic hematopoietic stem cell transplantation: Six-year follow up.

BACKGROUND: Infections with human ß-herpesviruses are common worldwide and are still frequent in patients after hematopoietic stem cell transplantation. Some data suggest that HHV-6 and HHV-7 could take part in CMV reactivation from latency and/or progression of CMV disease in immunosupressed patients. OBJECTIVES: The aims of this study were: (1) to summarise retrospectively the results of ß-herpesviruses DNA detection in a large group of adult allogeneic haematopoietic stem cell transplant recipients; and (2) to find a potential correlation between viruses belonging to this subfamily. STUDY DESIGN: AlloHSCT recipients (N=142) were examined in the early post-transplant period (median=89 days). The presence of CMV, HHV-6 and HHV-7 was confirmed through detection and quantification of viral DNA, isolated from 1679 sera samples. RESULTS: CMV DNA alone was detected in 23.9% of patients, while single HHV-6 and HHV-7 were detected in 14.8% and 9.9% of individuals, respectively. The reactivation of more than one virus was identified in 31% of analysed patients. In cases of concurrent infection, HHV-7 was detected at the same time as HHV-6, and both of them were usually reactivated before CMV. The kinetics of virus reactivation and measured viral load may suggest a potential role of HHV-6 and HHV-7 as co-factors in CMV reactivation. CONCLUSIONS: The observed kinetics of virus reactivation may strongly suggest a potential role of HHV-6 and/or HHV-7 as co-factors of CMV reactivation. The co-infection with these ß-herpesviruses could predispose patients after hematopoietic stem cell transplantation to a longer and more severe CMV infection.

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.

Association between Herpesviruses and Chronic Periodontitis: A Meta-Analysis Based on Case-Control Studies.

OBJECTIVE: Numerous studies have investigated the associations between herpesviruses and chronic periodontitis; however, the results remain controversial. To derive a more precise estimation, a meta-analysis on all available studies was performed to identify the association between herpesviruses and chronic periodontitis. METHODS: A computerized literature search was conducted in December 2014 to identify eligible case-control studies from the PUBMED and EMBASE databases according to inclusion and exclusion criteria. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were used to assess the association between herpesviruses and risk of chronic periodontitis. A fixed or random effects model was determined based on a heterogeneity test. Sensitivity analysis was conducted to investigate stability and reliability. Publication bias was investigated using the Begg rank correlation test and Egger's funnel plot. RESULTS: Ten eligible studies were included to investigate the association between Epstein-Barr virus (EBV) and chronic periodontitis. The results showed that EBV has a significant association with chronic periodontitis compared with periodontally healthy group (OR = 5.74, 95% CI = 2.53-13.00, P<0.001). The association between human cytomegalovirus (HCMV) and chronic periodontitis was analyzed in 10 studies. The pooled result showed that HCMV also has a significant association with chronic periodontitis (OR = 3.59, 95% CI = 1.41-9.16, P = 0.007). Similar results were found in the sensitivity analyses. No significant publication bias was observed. Two eligible studies were included to investigate the association between herpes simplex virus (HSV) and chronic periodontitis risk. The association between HSV and chronic periodontitis was inconclusive (OR = 2.81 95% CI = 0.95-8.27, P = 0.06). Only one included study investigated the association between human herpesvirus 7 (HHV-7) and chronic periodontitis risk (OR = 1.00, 95% CI = 0.21-4.86). CONCLUSION: The findings of this meta-analysis suggest that two members of the herpesvirus family, EBV and HCMV, are significantly associated with chronic periodontitis. There is insufficient evidence to support associations between HSV, HHV-7 and chronic periodontitis.

Roseolovirus molecular biology: recent advances.

Human herpesviruses 6A, 6B, and 7 (HHV-6A, HHV-6B, and HHV-7) are classified within the roseolovirus genus of the betaherpesvirus subfamily. Most humans likely harbor at least two of these large DNA viruses, and 1% of humans harbor germline chromosomally integrated (ci) HHV-6A or HHV-6B genomes. Differences at the genetic level manifest as distinct biologic properties during infection and disease. We provide a brief synopsis of roseolovirus replication and highlight the unique properties of their lifecycle and what is known about the viral gene products that mediate these functions. In the nearly 30 years since their discovery, we have only begun to unlock the molecular strategies these highly evolved pathogens employ to establish and maintain chronic infections in humans.

Clinical impact of primary infection with roseoloviruses.

The roseoloviruses, human herpesvirus-6A -6B and -7 (HHV-6A, HHV-6B and HHV-7) cause acute infection, establish latency, and in the case of HHV-6A and HHV-6B, whole virus can integrate into the host chromosome. Primary infection with HHV-6B occurs in nearly all children and was first linked to the clinical syndrome roseola infantum. However, roseolovirus infection results in a spectrum of clinical disease, ranging from asymptomatic infection to acute febrile illnesses with severe neurologic complications and accounts for a significant portion of healthcare utilization by young children. Recent advances have underscored the association of HHV-6B and HHV-7 primary infection with febrile status epilepticus as well as the role of reactivation of latent infection in encephalitis following cord blood stem cell transplantation.

Roseoloviruses and their modulation of host defenses.

Human cytomegalovirus (HCMV), the prototypical human ß-herpesvirus, encodes approximately 40 known gene products that function to subvert our host defense mechanisms. From HCMV, we have learned about interferon signaling, cytokine function, chemokine signaling, natural killer (NK) cells' cytotoxicity toward tumors and virus-infected cells, antigen processing and presentation, and protective initiation of the apoptotic signaling cascade. With each successive discovery of novel host evasion mechanism encoded by the cytomegaloviruses, we illuminate what these herpesviruses have learned over the course of their 100 MYr-long evolution with their hosts. As much as we have learned from HCMV, the other members of the human ß-herpesvirus family, HHV-6 and HHV-7, are closely-related and yet largely unexplored. These viruses likely have much yet to teach us.

EBV, HCMV, HHV6, and HHV7 screening in bone marrow samples from children with acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is the most common cancer in childhood worldwide and Mexico has reported one of the highest incidence rates. An infectious etiology has been suggested and supported by epidemiological evidences; however, the identity of the involved agent(s) is not known. We considered that early transmitted lymphotropic herpes viruses were good candidates, since transforming mechanisms have been described for them and some are already associated with human cancers. In this study we interrogated the direct role of EBV, HCMV, HHV6, and HHV7 human herpes viruses in childhood ALL. Viral genomes were screened in 70 bone marrow samples from ALL patients through standard and a more sensitive nested PCR. Positive samples were detected only by nested PCR indicating a low level of infection. Our result argues that viral genomes were not present in all leukemic cells, and, hence, infection most likely was not part of the initial genetic lesions leading to ALL. The high statistical power of the study suggested that these agents are not involved in the genesis of ALL in Mexican children. Additional analysis showed that detected infections or coinfections were not associated with prognosis.