Reactivation of human herpesvirus 6 during pregnancy

Pregnancy, infection, and epigenetic regulation: A complex scenario

A unique immunological condition, pregnancy ensures fetus from maternal rejection, allows adequate fetal development, and protects against microorganisms. Infections during pregnancy may lead to devastating consequences for pregnant women and fetuses, resulting in the mother's death, miscarriage, premature childbirth, or neonate with congenital infection and severe diseases and defects. Epigenetic (heritable changes in gene expression) mechanisms like DNA methylation, chromatin modification, and gene expression modulation during gestation are linked with the number of defects in the fetus and adolescents. The feto-maternal crosstalk for fetal survival during the entire gestational stages are tightly regulated by various cellular pathways, including epigenetic mechanisms that respond to both internal as well outer environmental factors, which can influence the fetal development across the gestational stages. Due to the intense physiological, endocrinological, and immunological changes, pregnant women are more susceptible to bacterial, viral, parasitic, and fungal infections than the general population. Microbial infections with viruses (LCMV, SARS-CoV, MERS-CoV, and SARS-CoV-2) and bacteria (Clostridium perfringens, Coxiella burnetii, Listeria monocytogenes, Salmonella enteritidis) further increase the risk to maternal and fetal life and developmental outcome. If the infections remain untreated, the possibility of maternal and fetal death exists. This article focused on the severity and susceptibility to infections caused by Salmonella, Listeria, LCMV, and SARS-CoV-2 during pregnancy and their impact on maternal health and the fetus. How epigenetic regulation during pregnancy plays a vital role in deciding the fetus's developmental outcome under various conditions, including infection and other stress. A better understanding of the host-pathogen interaction, the characterization of the maternal immune system, and the epigenetic regulations during pregnancy may help protect the mother and fetus from infection-mediated outcomes.

Dynamics of salivary human herpesvirus-6 and -7 shedding in pregnant women

OBJECTIVES

Reactivation of Betaherpesvirinae (Human herpesvirus 6A: HHV-6A, -6B, HHV-7) may be associated with mental illness and host fatigue. This study aimed to determine whether viral reactivation, measured by monitoring salivary viral DNA load, can be used to monitor depression in pregnant and postpartum women.

METHODS

Saliva samples were collected from 64 pregnant women at five-point of observation periods. The HHV-6 and HHV-7 specific qPCRs were carried out to measure viral DNA load. When HHV-6 DNA was detected in saliva, nested PCR was used to discriminate between HHV-6A and B.

RESULTS

In both viruses, a significant correlation was observed between detection frequency and viral DNA load in saliva. In the low-shedding group, HHV-6 DNA was significantly higher in the third trimester (P<0.0001), the time of delivery (P=0.0003), one month after birth (P=0.0023) compared to the first trimester, and HHV-7 was at the time of delivery (P=0.0277) and one month after birth (P=0.0235). Most of detected HHV-6 DNAs in saliva were HHV-6B. Both viral DNA loads were significantly lower (HHV-6:P=0.0101, HHV-7:P=0.0044) in the subjects with abnormal EPDS scores.

CONCLUSIONS

Detection rate and viral DNA load of both viruses in saliva increased after the third trimester. Salivary virus DNA shedding was significantly lower in subjects with an abnormal EPDS score. This article is protected by copyright. All rights reserved.

Chronic Alcoholism and HHV-6 Infection Synergistically Promote Neuroinflammatory Microglial Phenotypes in the Substantia Nigra of the Adult Human Brain

Both chronic alcoholism and human herpesvirus-6 (HHV-6) infection have been identified as promoters of neuroinflammation and known to cause movement-related disorders. Substantia Nigra (SN), the dopaminergic neuron-rich region of the basal ganglia, is involved in regulating motor function and the reward system. Hence, we hypothesize the presence of possible synergism between alcoholism and HHV-6 infection in the SN region and report a comprehensive quantification and characterization of microglial functions and morphology in postmortem brain tissue from 44 healthy, age-matched alcoholics and chronic alcoholics. A decrease in the perivascular CD68+ microglia in alcoholics was noted in both the gray and white matter. Additionally, the CD68+/Iba1− microglial subpopulation was found to be the dominant type in the controls. Conversely, in alcoholics, dystrophic changes in microglia were seen with a significant increase in Iba1 expression and perivascular to diffuse migration. An increase in CD11b expression was noted in alcoholics, with the Iba1+/CD11b− subtype promoting inflammation. All the controls were found to be negative for HHV-6 whilst the alcoholics demonstrated HHV-6 positivity in both gray and white matter. Amongst HHV-6 positive alcoholics, all the above-mentioned changes were found to be heightened when compared with HHV-6 negative alcoholics, thereby highlighting the compounding relationship between alcoholism and HHV-6 infection that promotes microglia-mediated neuroinflammation.

Maternal natural killer cells at the intersection between reproduction and mucosal immunity

Many maternal immune cells populate the decidua, which is the mucosal lining of the uterus transformed during pregnancy. Here, abundant natural killer (NK) cells and macrophages help the uterine vasculature adapt to fetal demands for gas and nutrients, thereby supporting fetal growth. Fetal trophoblast cells budding off the forming placenta and invading deep into maternal tissues come into contact with these and other immune cells. Besides their homeostatic functions, decidual NK cells can respond to pathogens during infection, but in doing so, they may become conflicted between destroying the invader and sustaining fetoplacental growth. We review how maternal NK cells balance their double duty both in the local microenvironment of the uterus and systemically, during toxoplasmosis, influenza, cytomegalovirus, malaria and other infections that threat pregnancy. We also discuss recent developments in the understanding of NK-cell responses to SARS-Cov-2 infection and the possible dangers of COVID-19 during pregnancy.

Is the ZIKV Congenital Syndrome and Microcephaly Due to Syndemism with Latent Virus Coinfection?

The emergence of the Zika virus (ZIKV) mirrors its evolutionary nature and, thus, its ability to grow in diversity or complexity (i.e., related to genome, host response, environment changes, tropism, and pathogenicity), leading to it recently joining the circle of closed congenital pathogens. The causal relation of ZIKV to microcephaly is still a much-debated issue. The identification of outbreak foci being in certain endemic urban areas characterized by a high-density population emphasizes that mixed infections might spearhead the recent appearance of a wide range of diseases that were initially attributed to ZIKV. Globally, such coinfections may have both positive and negative effects on viral replication, tropism, host response, and the viral genome. In other words, the possibility of coinfection may necessitate revisiting what is considered to be known regarding the pathogenesis and epidemiology of ZIKV diseases. ZIKV viral coinfections are already being reported with other arboviruses (e.g., chikungunya virus (CHIKV) and dengue virus (DENV)) as well as congenital pathogens (e.g., human immunodeficiency virus (HIV) and cytomegalovirus (HCMV)). However, descriptions of human latent viruses and their impacts on ZIKV disease outcomes in hosts are currently lacking. This review proposes to select some interesting human latent viruses (i.e., herpes simplex virus 2 (HSV-2), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), human parvovirus B19 (B19V), and human papillomavirus (HPV)), whose virological features and co-exposition with ZIKV may provide evidence of the syndemism process, shedding some light on the emergence of the ZIKV-induced global congenital syndrome in South America.

Comprehensive health assessment of green turtles Chelonia mydas nesting in southeastern Florida, USA

Important indicators of population health needed for large-scale sea turtle population recovery efforts include demographics, disease and mortality trends, condition indices, and baseline blood data. With this comprehensive health assessment of adult female green sea turtles Chelonia mydas nesting on Juno Beach, Florida, USA, we (1) established comprehensive baseline health indices; (2) identified individuals with evidence of infection by chelonid alphaherpesviruses 5 and 6 (ChHV5, ChHV6), which are implicated in fibropapillomatosis and respiratory and skin disease, respectively; and (3) compared measured health indices between turtles that did versus those that did not test positive for ChHV5 and/or ChHV6. All 60 turtles included in the study were in good body condition with no external fibropapillomatosis tumors. Hematological and biochemical reference intervals were established. Via quantitative PCR (qPCR), 5/60 turtles (8%) tested positive for ChHV5, and all turtles were negative for ChHV6. Of 41 turtles tested for antibodies to ChHV5 and ChHV6, 29% and 15% tested positive, respectively, and 10% tested positive for antibodies to both viruses. Notably, there were no statistically significant differences between health variables for nesting turtles that tested positive for ChHV5 DNA versus those that tested negative; and also no differences between turtles that tested positive for ChHV5 or ChHV6 antibodies and those that did not. This suggests that these viruses are enzootically stable in Florida’s adult green turtles. This study provides a health profile of nesting green turtles in southeastern Florida applicable to temporal and spatial investigations of this and other populations.

Antibodies to Human Herpesviruses in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients

Myalgic encephalomyelitis, also referred to as chronic fatigue syndrome (ME/CFS) is a debilitating disease characterized by myalgia and a sometimes severe limitation of physical activity and cognition. It is exacerbated by physical and mental activity. Its cause is unknown, but frequently starts with an infection. The eliciting infection (commonly infectious mononucleosis or an upper respiratory infection) can be more or less well diagnosed. Among the human herpesviruses (HHV-1-8), HHV-4 (Epstein-Barr virus; EBV), HHV-6 (including HHV-6A and HHV-6B), and HHV-7, have been implicated in the pathogenesis of ME/CFS. It was therefore logical to search for serological evidence of past herpesvirus infection/reactivation in several cohorts of ME/CFS patients (all diagnosed using the Canada criteria). Control samples were from Swedish blood donors. We used whole purified virus, recombinant proteins, and synthetic peptides as antigens in a suspension multiplex immunoassay (SMIA) for immunoglobulin G (IgG). The study on herpesviral peptides based on antigenicity with human sera yielded novel epitope information. Overall, IgG anti-herpes-viral reactivities of ME/CFS patients and controls did not show significant differences. However, the high precision and internally controlled format allowed us to observe minor relative differences between antibody reactivities of some herpesviral antigens in ME/CFS versus controls. ME/CFS samples reacted somewhat differently from controls with whole virus HHV-1 antigens and recombinant EBV EBNA6 and EA antigens. We conclude that ME/CFS samples had similar levels of IgG reactivity as blood donor samples with HHV-1-7 antigens. The subtle serological differences should not be over-interpreted, but they may indicate that the immune system of some ME/CFS patients interact with the ubiquitous herpesviruses in a way different from that of healthy controls.

Pityriasis rosea in pregnancy: report of a spousal occurrence and craniosynostosis in the healthy newborn

BACKGROUND

Pityriasis rosea is a papulosquamous disease. It may occur during pregnancy; in this setting, it has occasionally been associated with adverse outcomes.

PURPOSE

A woman who developed pityriasis rosea at the beginning of her eighth week of gestation is described. The outcomes in newborns delivered by pregnant women who developed pityriasis rosea during gestation are summarized.

METHOD

A 28-year-old woman developed pityriasis rosea during her eighth week of pregnancy. Her husband had pityriasis rosea two months earlier. PubMed was searched for the following terms: conjugal, craniosynostosis, newborn, pityriasis, pregnancy, rosea, sagittal, spouse. The papers were reviewed and the references cited were evaluated.

RESULTS

Our patient delivered a healthy male infant after 41 weeks of gestation. He had normal weight, height, and Apgar scores. Isolated sagittal craniosynostosis was diagnosed and was successfully treated at nine weeks after birth without complications.

CONCLUSION

Several retrospective studies have investigated the possibility of adverse outcomes in infants born to women who developed pityriasis rosea during pregnancy, such as stillbirth, low gestational weight, hypotonia, and premature delivery. However, there are also reports of healthy newborns in women who have had pityriasis rosea during gestation. Our patient carried the fetus one week post-term and delivered a healthy boy via C-section; isolated sagittal craniosynostosis was later diagnosed and successfully repaired. The occurrence of craniosynostosis in a woman who developed pityriasis rosea during her first trimester of pregnancy may be two coincidental events.

Ocular toxoplasmosis: background and evidence for an antibiotic prophylaxis

PURPOSE OF REVIEW

The purpose of this review was to provide an overview of current data on antibiotic prophylaxis in ocular toxoplasmosis.

RECENT FINDINGS

Studies showing the prophylactic effect of long-term antibiotics are discussed. Prophylaxis seems to be justified in patients with a high risk of recurrence because of antibiotic's potential side-effects. Therefore, predisposing factors leading to a higher risk of recurrence and the time period during which an antibiotic prophylaxis is most appropriate are reviewed. Finally, a patient-individualized treatment recommendation is summarized.

SUMMARY

In the current literature, two prospective, randomized case-control studies exist, which show the protective effect of an antibiotic prophylaxis. Hematologic, gastrointestinal and dermatologic complications are potential side-effects. Especially during the first year after suffering a recurrence, an antibiotic prophylaxis seems to be justified. The risk of a recurrence is inter alia influenced by the duration of the disease, the immune status of the host and the patient's age. Therefore, an antibiotic prophylaxis should be considered for patients who have recently been infected with ocular toxoplasmosis, for middle-aged and elderly patients and patients with a compromised immune system. This should be discussed with each patient individually, especially if the lesion is close to the macula.

Longitudinal study of Asian elephants, Elephas maximus, indicates intermittent shedding of elephant endotheliotropic herpesvirus 1 during pregnancy

Introduction

EEHV-1 is a viral infection of elephants that has been associated with a fatal haemorrhagic syndrome in Asian elephants. Previous studies have suggested that pregnant animals may shed more virus than non-pregnant animals.

Methods

This study examined whether pregnancy affected the frequency or magnitude of shedding of elephant endotheliotropic herpesvirus 1 (EEHV1) using Taq man real-time PCR on trunk washes from four female elephants from a UK collection over three time periods between 2011 and 2014. These periods included pregnancies in two animals (period 1 and period 3). Behavioural observations made by keepers were also assessed.

Results

During period 1 there was a high degree of social hierarchical instability which led to a hierarchy change, and was associated with aggressive behaviour. Also during period 1 EEHV-1 shedding was of a higher magnitude and frequency than in the latter two time periods.

Conclusions

These results suggest that there is no clear relationship between shedding and pregnancy, and that behavioural stressors may be related to an increase in EEHV-1 shedding.

Prevalence of human herpesvirus 6A and 6B during pregnancy

The aim of the present study was to assess the frequency of human herpesvirus 6A (HHV-6A) and human herpesvirus 6B (HHV-6B) infection during pregnancy. 100-100 blood samples were collected from pregnant and non-pregnant women, then nucleic acid was isolated from both plasma and leukocytes fraction. Nested and real-time PCR were used to detect and differentiate HHV-6A and HHV-6B DNA and to determine viral loads. Reverse transcription PCR (RT-PCR) for HHV-6 U79/80 mRNA was performed in order to reveal active HHV-6 replication.HHV-6A and HHV-6B active infections were not detected in blood samples neither from pregnant nor from non-pregnant women. Frequency of HHV-6B and HHV-6A latency did not show difference between the studied groups (15% vs. 16%). HHV-6B latency was dominant in both studied groups (14/15 and 15/16). Beside these results, in leukocyte samples of one pregnant and three non-pregnant women high HHV-6A viral loads (1.28 × 10⁵ - 5.07 × 10⁵ GEq / 1.5 × 10⁶ leukocytes) were detected, and viral DNA was also found in plasma samples. Although RT-PCR did not confirm virus replication, but chromosomal integration was also not proved unequivocally, the number of 0.08-0.33 HHV-6 copy / 1 leukocyte refers more to postnatal infection.

Risk of Recurrence of Preexisting Ocular Toxoplasmosis during Pregnancy

PURPOSE

Comparison between the risk of recurrence during pregnancy with nonpregnant periods in patients with ocular toxoplasmosis (OT).

METHODS

Records of 40 women were retrospectively reviewed. The women were subdivided into either a pregnant group or a control group formed by nonpregnant women during follow-up. Comparable cases from the literature were added. Mean number of recurrences per year was compared.

RESULTS

Eleven women with pregnancies could be included. Six cases from the literature were added (total n = 17). Mean number of recurrences per year during versus not during pregnancy was 0.16 (SD 0.39) versus 0.32 (SD 0.30; p = 0.088), respectively. In the control group (n = 29) the mean number of recurrences per year (0.31; SD 0.27) was significantly higher when compared to cases during pregnant periods (p = 0.002).

CONCLUSION

Adding to published series, the presented data do not provide evidence for a relevant impact of pregnancy on recurrence behavior in OT.

Recurrence rates of ocular toxoplasmosis during pregnancy

PURPOSE

To investigate whether recurrence rates of ocular toxoplasmosis are higher during pregnancy in women of childbearing age.

DESIGN

Retrospective longitudinal cohort study.

METHODS

We reviewed medical records of all women seen at a university eye clinic (Utrecht, Netherlands) during episodes of active toxoplasmic retinochoroiditis that occurred while the women were of childbearing age (16-42 years). Each woman was sent a questionnaire requesting information regarding all pregnancies and episodes of ocular toxoplasmosis, whether or not episodes were observed at the eye clinic. Conditional fixed-effects Poisson regression was used to model incidence rate ratios of recurrence during pregnant versus nonpregnant intervals, adjusted for potential confounders, including age at time of active toxoplasmic retinochoroiditis and interval since last episode of active disease, which are known to influence risk for recurrence.

RESULTS

Questionnaires were returned by 50 (58%) of 86 women, 34 of whom had had 69 pregnancies during 584 person-years of study. There were 128 episodes of ocular toxoplasmosis during the study period (6 during pregnancy). First episodes of ocular toxoplasmosis occurred between ages 9.6 and 38.5 years. The youngest age at pregnancy was 16.1 years; the oldest age at childbirth was 40.9 years. The incidence-rate ratios for pregnant versus nonpregnant intervals were in the direction of lower recurrence rates during pregnancy, with point estimates of 0.54 and 0.75 under 2 different approaches, but the ratios were not significantly different from the null value (P values of 0.16 and 0.55).

CONCLUSIONS

Recurrence rates of ocular toxoplasmosis are probably not higher during pregnancy, in contrast to traditional beliefs.

Role of the infections in recurrent spontaneous abortion

Embryo-fetal infections have been reported to cause recurrent spontaneous abortions (RSAs) at a rate lower than 4%. The possible mechanisms include production of toxic metabolic byproducts, fetal or placental infection, chronic endometrial infection, and chorio-amnionitis. Viruses appear to be the most frequently involved pathogens, since some of them can produce chronic or recurrent maternal infection. In particular, cytomegalovirus during pregnancy can reach the placenta by viremia, following both primary and recurrent infection, or by ascending route from the cervix, mostly following reactivation. Another herpesvirus, herpes simplex virus type 2, less frequently type 1, causes recurrent infections of the genital tract, which can involve the feto-placental unit. Parvoviruses have also been implicated in the development of repeated fetal loss. Among bacterial infections, Chlamydia trachomatis, Ureaplasma urealyticum,and Mycoplasma hominis have been mostly associated with occurrence of RSA. An increased risk of abortion among women with bacterial vaginosis (BV) during early pregnancy was also shown, but questions arise about the role of chronic BV in its occurrence. Although a definitive relationship between recurrently active infections and RSA is still lacking, mostly due to difficulties in demonstrating the pathogenic role of each individual isolated pathogen, diagnosis and therapy of RSA-related infections should be attempted. The diagnosis of infectious agents as a possible cause of RSA might lead to a therapeutic approach with antiviral drugs and antibiotics or using immunoglobulins, which can display both anti-infective neutralizing and immunomodulating properties.

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

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

Clinical features of ocular toxoplasmosis during pregnancy

PURPOSE

To evaluate the ocular characteristics of active ocular toxoplasmosis (OT) during pregnancy in nine female patients and to compare these attacks with those in the nonpregnant periods.

METHODS

Retrospective analysis of active OT during pregnancy and the nonpregnant periods. Outcome measurements consisted of the duration of attacks, the size of the retinal lesions, treatment strategies, and diverse ocular features and outcomes.

RESULTS

The 9 patients had 10 attacks during pregnancy and 24 attacks while not pregnant. One woman had recurrences during several pregnancies, and in total, three female patients had attacks only when pregnant. In general, the severity of the attacks during the pregnant and nonpregnant periods did not differ.

CONCLUSION

The attacks during pregnancy were not distinctively different in severity, duration, or outcome from the OT attacks outside pregnancy.

Chromosomal integration of human herpesvirus 6 is the major mode of congenital human herpesvirus 6 infection

OBJECTIVE

We examined the frequency and characteristics of chromosomally integrated human herpesvirus 6 among congenitally infected children.

METHODS

Infants with and without congenital human herpesvirus 6 infection were prospectively monitored. Cord blood mononuclear cell, peripheral blood mononuclear cell, saliva, urine, and hair follicle samples were examined for human herpesvirus 6 DNA. Human herpesvirus 6 RNA, serum antibody, and chromosomally integrated human herpesvirus 6 levels were also assessed.

RESULTS

Among 85 infants, 43 had congenital infections and 42 had postnatal infections. Most congenital infections (86%) resulted from chromosomally integrated human herpesvirus 6; 6 infants (14%) had transplacental infections. Children with chromosomally integrated human herpesvirus 6 had high viral loads in all sites (mean: 5-6 log(10) genomic copies per mug of cellular DNA); among children with transplacental infection or postnatal infection, human herpesvirus 6 DNA was absent in hair samples and inconsistent in other samples, and viral loads were significantly lower. One parent of each child with chromosomally integrated human herpesvirus 6 who had parental hair samples tested had hair containing human herpesvirus 6 DNA. Variant A caused 32% of chromosomally integrated human herpesvirus 6 infections, compared with 2% of postnatal infections. Replicating human herpesvirus 6 was detected only among chromosomally integrated human herpesvirus 6 samples (8% of cord blood mononuclear cells and peripheral blood mononuclear cells). Cord blood human herpesvirus 6 antibody levels were similar among children with chromosomally integrated human herpesvirus 6, transplacental infection, and postnatal infection and between children with maternal and paternal chromosomally integrated human herpesvirus 6 transmission.

CONCLUSIONS

Human herpesvirus 6 congenital infection results primarily from chromosomally integrated virus which is passed through the germ-line. Infants with chromosomally integrated human herpesvirus 6 had high viral loads in all specimens, produced human herpesvirus 6 antibody, and mRNA. The clinical relevance needs study as 1 of 116 newborns may have chromosomally integrated human herpesvirus 6 blood specimens.

Human herpesvirus 6 DNA levels in cerebrospinal fluid due to primary infection differ from those due to chromosomal viral integration and have implications for diagnosis of encephalitis

The prevalence and concentration of human herpesvirus 6 (HHV-6) DNA in the cerebrospinal fluid (CSF) of the immunocompetent in primary infection was compared with that in viral chromosomal integration. Samples from 510 individuals with suspected encephalitis, 200 young children and 310 older children and/or adults, and 12 other patients were tested. HHV-6 DNA concentration (log(10) copies/ml) was measured in CSF, serum, and whole blood using PCR. Serum HHV-6 immunoglobulin G antibody was measured by indirect immunofluorescence. Primary infection was defined by antibody seroconversion and/or a low concentration of HHV-6 DNA (<3.0 log(10) copies/ml) in a seronegative serum. Chromosomal integration was defined by a high concentration of viral DNA in serum (>/=3.5 log(10) copies/ml) or whole blood (>/=6.0 log(10) copies/ml). The prevalences of CSF HHV-6 DNA in primary infection and chromosomal integration were 2.5% and 2.0%, respectively, in the young children (<2 years) and 0% and 1.3%, respectively, in the older children and/or adults. The mean concentration of CSF HHV-6 DNA in 9 children with primary infection (2.4 log(10) copies/ml) was significantly lower than that of 21 patients with viral chromosomal integration (4.0 log(10) copies/ml). Only HHV-6B DNA was found in primary infection, whereas in viral integration, 4 patients had HHV-6A and 17 patients HHV-6B. Apart from primary infection, chromosomal integration is the most likely cause of HHV-6 DNA in the CSF of the immunocompetent. Our results show that any diagnosis of HHV-6 encephalitis or other type of active central nervous system infection should not be made without first excluding chromosomal HHV-6 integration by measuring DNA load in CSF, serum, and/or whole blood.

The prevalence of chromosomally integrated human herpesvirus 6 genomes in the blood of UK blood donors

A lesser-recognized form of human herpesvirus 6 (HHV-6) persistence is integration of the viral genome in a host chromosome and high viral copy numbers in blood or sera are characteristic of this phenomenon. A cross-sectional study was performed to determine the frequency of high HHV-6 viral loads in whole blood (>6 log(10) copies/ml) in a population of blood donors in London, UK. Blood samples from 500 anonymized blood donors were collected from one donation center, DNA extracted, and quantitative realtime PCR used to measure viral load. Four samples (0.8%) were found to have high viral copy numbers of HHV-6 (median 6.7 log(10) copies/ml; range 6.5- 6.9 log(10) copies/ml). Cellular DNA was also quantitated using qRT-PCR for beta-globin. By comparing these two results, we calculated that there were between two and five copies of HHV-6 present per cell in these four donors. The median viral load detected in plasma from the four individuals was 3.8 log(10) copies/ml (range 3.5-4.0 log(10) copies/ml). All samples were HHV-6 variant B. In addition, a retrospective analysis of all diagnostic blood samples performed for HHV-6 in our center showed a prevalence of 2.9% of high viral loads characteristic of integration. In conclusion, high viral copy numbers of HHV-6, representing a population of viral integration, is detected in 0.8% of UK blood donors. The presence of high HHV-6 viral loads in healthy normal individuals reiterates the need to consider the confounding effect of HHV-6 viral integration in any laboratory diagnosis of HHV-6 infection.

Pregnancy and human herpesvirus 8 reactivation in human immunodeficiency virus type 1-infected women

To investigate the impact of pregnancy on human herpesvirus 8 (HHV-8) reactivation in human immunodeficiency virus type 1 (HIV-1)-infected women, the HHV-8 DNA presence and load were analyzed in peripheral blood mononuclear cells (PBMCs) and cervicovaginal secretions (CVSs) from 15 pregnant women coinfected with HIV-1 and HHV-8. HHV-8 detection was analyzed in relation to anti-HHV-8 antibodies and HIV-1-related parameters. Nucleotide sequence analysis of an ORFK1 hypervariable region of the HHV-8 strains was performed. HHV-8 was detected in maternal PBMCs (5/15 women) from the second trimester and in CVSs (5/15 women) mainly from the third trimester. The HHV-8 load significantly increased late in pregnancy in both maternal compartments and was associated with a significant increase in HIV-1 shedding in the genital tract. Antilytic antibodies were significantly more common in HHV-8 DNA-positive women. An elevated HHV-8 load was found in the PBMCs of an infant born to a mother with large amounts of HHV-8 in both compartments at delivery. Different ORFK1 subtypes were found in maternal samples, whereas the same subtype was identified in the mother-child pair. These data suggest that pregnancy may induce HHV-8 replication in HIV-1-infected women. An augmented HHV-8 load may, in turn, influence mother-to-child transmission, since one of the HIV-1-infected mothers with HHV-8 reactivation transmitted her ORFK1 subtype to the infant, who showed a high level of HHV-8 viremia indicative of a primary infection. This finding documents for the first time the perinatal transmission of a specific HHV-8 subtype. Vertical transmission may thus play a role in HHV-8 spread also in areas of subendemicity among HIV-1-infected women.

Prevalence and avidity of human herpesvirus-6 specific IgG antibodies in pregnant women in Hungary

The prevalence, the level and the avidity of human herpesvirus-6 (HHV-6) specific IgG were examined in pregnant women and age-matched female blood donors. The study group consisted of 180 women (age 14-45); 60 women with normal pregnancy, 60 pregnant women with fetuses suspected of having any viral infection and 60 healthy blood donors with no history of pregnancy. Plasma or serum samples were tested for HHV-6 IgG antibodies by an immunofluorescence assay. Ninety-eight percent of blood donors and 97% of 120 pregnant women had IgG antibodies to HHV-6. The rate of seropositivity in women with normal pregnancies and women with fetuses suspected to have viral infection was the same. Pregnant women (n = 120) had significantly lower antibody titer than blood donors. No significant differences were found in the same respect between the two groups of pregnant women. Low avidity of IgG antibodies to HHV-6 was detected in 5% of pregnant women.

The natural history and laboratory diagnosis of human herpesviruses-6 and -7 infections in the immunocompetent

BACKGROUND

Human herpesviruses-6 and -7 (HHV-6/7) are widespread in all populations. In some individuals HHV-6 is found integrated into human chromosomes, which results in a high viral load in blood. HHV-6 variant B (HHV-6B) and HHV-7 primary infections, although usually silent, not infrequently cause the childhood exanthem roseola infantum and are sometimes accompanied by neurological illness. HHV-6 variant A (HHV-6A) is not associated with any disease.

OBJECTIVES

The present review focuses on the immunocompetent individual and considers the epidemiology of the two viruses and their role as human pathogens. It discusses the importance of satisfactory diagnostic tests to distinguish them, compares those currently available, and recommends how best to differentiate primary from persistent infection in each case.

RESULTS

It is explained that at the present time antibody avidity immunofluorescence tests are the most reliable discriminators of the two types of infection. In primary infection these tests can be supplemented by PCR for viral DNA in blood but careful interpretation is required for HHV-6 in view of the high persistent viral DNA load seen with chromosomal integration. Since the contribution of primary HHV-6 and -7 infections to the burden of severe neurological illness in young children is only now emerging as significant, the need to test for these viruses in such cases is stressed.

CONCLUSIONS

1. Primary HHV-6/7 infections must be distinguished from persistent infections. 2. Chromosomal integration of HHV-6 requires urgent study. 3. HHV-6A/B must be distinguished in clinical situations. 4. Where serious neurological disease/encephalitis is temporally related to immunisation it is particularly important to test for HHV-6/7 primary infection since otherwise the condition might wrongly be diagnosed as a vaccine reaction. 5. Because less is currently known about HHV-7 and HHV-6A than HHV-6B, future studies should concentrate on the former two. 6. Improvements in diagnostic tests are required for each virus.

Risk of transmission of herpesviruses through cord blood transplantation

Cord blood (CB) progenitor cells are increasingly used for transplantation in children because of the lower risk of graft-versus-host disease compared with unrelated bone marrow and comparable rates of disease-free survival. There is concern that CB might carry a higher risk of opportunistic infections. Human herpesviruses (HHV) are common pathogens in transplant recipients. CB donors are routinely tested for the presence of anti-cytomegalovirus (CMV) immunoglobulin M to reduce the risk of collecting CMV-infected CB. To assess the incidence of beta and gamma HHV infection of CB collected under standard procedures, we tested 362 CB samples for the presence of CMV; HHV-6, -7, and -8; and Epstein-Barr virus DNA by polymerase chain reaction. HHV-6 DNA was found in 2 samples, yielding an incidence of 0.55% (95% confidence interval, 0.1%-2%). None of the other viral DNAs was found, resulting in a 95% confidence interval of 0% to 1% for the incidence of CMV, Epstein-Barr virus, HHV-7, and HHV-8. Because the seroprevalence of HHV-8 among the CB donors in this study was only 4%, these findings cannot be extended to HHV-8-endemic areas. Our data show that screening prospective CB donors with anti-CMV immunoglobulin M practically eliminates the risk of CB CMV transmission, but HHV-6 warrants CB testing by polymerase chain reaction.

Human herpesviruses-6 and -7 infections

PURPOSE OF REVIEW

To summarize the biology and clinical consequences of infection with the closely related human herpesviruses-6 and -7 (HHV-6/7) in children.

RECENT FINDINGS

Over the last year there has been a paucity of paediatric publications on HHV-6 and only two studies focused on HHV-7. Steady progress has been made regarding the biology and clinical consequences of HHV-6 infection whereas the effect of HHV-7 infection remains a neglected topic. However, both viruses have been shown to contribute significantly and equally to the burden of disease in young children with suspected encephalitis or severe convulsions with fever. There continues to be uncertainty as to the effects of HHV-6 infection after stem cell transplant, although there is general agreement that it contributes to encephalitis. In contrast, HHV-7 seems to have little clinical impact after stem cell transplant, although central nervous system infection and disease have recently been reported in children. Understanding the contribution of chromosomal integration and inheritance of both HHV-6 variants A and B (HHV-6A/B) and their effect on diagnosis is emerging.

SUMMARY

There is an urgent need for more research on HHV-6 and -7 in children, particularly in relation to chromosomal integration of HHV-6A and B, and clinical consequences of HHV-7 infection.

Unexpected occasional persistence of high levels of HHV-6 DNA in sera: Detection of variants A and B

Previously it was thought that in the immunocompetent human herpesvirus-6 [HHV-6] DNA was present transiently in serum during early primary infection but not thereafter. In this study, HHV-6 serum IgG avidity was detected by immunofluorescence and HHV-6 variants A/B [HHV-6A/B] serum DNA by semi-quantitative PCR [titre-log(10) copies/ml] in: (a) young children <3 years old from an encephalitis Survey, and a control Anonymised Serum Bank and (b) children/adults referred for diagnosis. The results showed that 11 out of 15 children [all <2 years] with primary infection proven by seroconversion had transient low levels of serum HHV-6B DNA [mean titre 2.6]. However, 3.3% (6/184) of Survey Children had significantly higher levels [mean titre 5.3; 2 HHV-6A; 4 HHV-6B; P < 0.001]. Similarly high level serum DNA [mean titre 4.0; 4 HHV-6A; 6 HHV-6B] was found in 1.5% (10/653) of the Serum Bank Children. Moreover, seven young children <3 years old [four Survey Children and three referred for diagnosis] had high titre serum HHV-6 DNA [mean 4.8] persisting i.e., in all available samples [median 186 days]. Three older children >3 years old and 4 adults [3 of whom were the mothers of 3 of the young children with persisting HHV-6] also had persisting high titre viral DNA [mean 4.2; median 108 days]. Thus in contrast to acute primary infection, where only HHV-6B DNA is found transiently, both HHV-6A and B DNA persist in serum at high titre in occasional individuals of all ages. The significance of this newly described phenomenon in relation to diagnosis, clinical consequences and congenital infection are discussed.

Update on human herpesvirus 6 biology, clinical features, and therapy

Human herpesvirus 6 (HHV-6) is a betaherpesvirus that is closely related to human cytomegalovirus. It was discovered in 1986, and HHV-6 literature has expanded considerably in the past 10 years. We here present an up-to-date and complete overview of the recent developments concerning HHV-6 biological features, clinical associations, and therapeutic approaches. HHV-6 gene expression regulation and gene products have been systematically characterized, and the multiple interactions between HHV-6 and the host immune system have been explored. Moreover, the discovery of the cellular receptor for HHV-6, CD46, has shed a new light on HHV-6 cell tropism. Furthermore, the in vitro interactions between HHV-6 and other viruses, particularly human immunodeficiency virus, and their relevance for the in vivo situation are discussed, as well as the transactivating capacities of several HHV-6 proteins. The insight into the clinical spectrum of HHV-6 is still evolving and, apart from being recognized as a major pathogen in transplant recipients (as exemplified by the rising number of prospective clinical studies), its role in central nervous system disease has become increasingly apparent. Finally, we present an overview of therapeutic options for HHV-6 therapy (including modes of action and resistance mechanisms).

Human herpesvirus type 6 and type 1 infection increases susceptibility to nonmelanoma skin tumors

In order to investigate herpesvirus (HHV) role in the susceptibility to skin cancer, we compared HHV6 and HHV1 incidence in DNA samples extracted from 120 lesions and 41 normal skin tissues. HHV6 (31.7%) and HHV1 (23.8%) were detected more frequently in skin cancer than in control individuals (14.6 and 5%, respectively) (P=0.0391 and P=0.00094, respectively). The risk of presenting basal cell carcinomas (BCC) was more than 3 times higher for HHV-6 infected patients (OR=3.182; 95% CI: 1.125-8.997). The risk for HHV-1 infected individuals of presenting BCC and squamous cell carcinomas was increased 8 and 6 times, respectively (OR=8.125; 95% CI: 1.735-38.043 and OR=6.290; 95% CI: 1.283-30.856, respectively).

Human herpes virus 6 or Epstein-Barr virus were not detected in Guthrie cards from children who later developed leukaemia

To investigate if children who later developed acute lymphoblastic leukaemia (ALL) were prenatally infected with HHV-6 and/or EBV, Guthrie cards taken at birth were analysed by PCR. Guthrie cards from 54 patients with ALL and 47 healthy controls matched for age and birth place were tested negative for both HHV-6 and EBV DNA. All samples contained amplifiable DNA when tested by HLA-DQ PCR. Our negative findings suggest that childhood ALL is unlikely to be associated with an in utero infection with EBV or HHV-6.

Congenital infections with human herpesvirus 6 (HHV6) and human herpesvirus 7 (HHV7)

OBJECTIVE

To examine whether: (1) congenital human herpesvirus 6 (HHV6) and human herpesvirus 7 (HHV7) infections occur; whether (2) their manifestations differ from postnatal infections; and whether (3) HHV6 and HHV7 infections differ despite their close relatedness.

STUDY DESIGN

HHV6 and HHV7 infections acquired congenitally and postnatally in normal children were compared using viral isolation, serology, reverse-transcription polymerase chain reaction (RT-PCR) and nested DNA-PCR for HHV6 variant A (HHV6A), HHV6 variant B (HHV6B), and HHV7.

RESULTS

HHV6 DNA was detected in 57 (1%) of 5638 cord bloods. HHV7 DNA, however, was not detected in 2129 cord bloods. Congenital HHV6 infections differed from postnatal infections, which were acute febrile illnesses. Congenital infections were asymptomatic, 10% demonstrated reactivation at birth, and HHV6 DNA persistence in follow-up blood samples was significantly more frequent. One-third of congenital infections were HHV6A, whereas all postnatal infections were HHV6B.

CONCLUSIONS

Congenital HHV6 infections occurred in 1% of births, similar to the rate for cytomegalovirus infection. Congenital infections were clinically and virologically distinct from postnatal infections. Congenital HHV7 infections, however, were not detected, suggesting considerable differences in transmission and pathogenesis in these closely related beta-herpesviruses.

Congenital infection with human herpesvirus 6 variant B associated with neonatal seizures and poor neurological outcome

Human herpesvirus 6 (HHV 6) has neurotropic and neuroinvasive properties. The virus has been found in the cerebrospinal fluid of many children with aseptic meningoencephalitis. Intrauterine transmission has been documented by HHV 6 DNA detection in cord blood specimens of apparently healthy newborns and in fetuses following spontaneous abortions. A patient is described with early neonatal afebrile seizures resulting from a congenital HHV 6 variant B infection disclosed by repeated detection of viral genome by polymerase chain reaction (PCR) in cerebrospinal fluid in the first days of life. At follow-up, magnetic resonance imaging (MRI) studies disclosed hyperintensities in the periventricular white matter and basal ganglia, associated with cerebral atrophy. Further follow-up at 18 months revealed poor neurological outcome with mild neurodevelopmental retardation, strabismus and hypertonia of legs. This report provides evidence of neurological involvement after HHV 6 vertical transmission, and the association with neurological sequelae.

Human herpesvirus 6: molecular biology and clinical features

Human herpesvirus 6 (HHV-6) exists as distinct variants HHV-6A and HHV-6B. The complete genomes of HHV-6A and HHV-6B have been sequenced. HHV-6B contains 97 unique genes. CD46 is the cell receptor for HHV-6, explaining its broad tissue tropism but its restricted host-species range. HHV-6 utilizes a number of strategies to down-regulate the host immune response, including molecular mimicry by production of a functional chemokine and chemokine receptors. Immunosuppression is enhanced by depletion of CD4 T lymphocytes via direct infection of intra-thymic progenitors and by apoptosis induction. Infection is widespread in infants between 6 months and 2 years of age. A minority of infants develop roseola infantum, but undifferentiated febrile illness is more common. Reactivation from latency occurs in immunocompromised hosts. Organ-specific clinical syndromes occasionally result, but indirect effects including interactions with other viruses such as human immunodeficiency virus type 1 and human cytomegalovirus or graft dysfunction in transplant recipients may be more significant complications in this population. Recent advances in quantitative PCR are providing additional insights into the natural history of infection in paediatric populations and immunocompromised hosts.

Reactivation of human herpesvirus 6 and 7 in pregnant women

To elucidate the roles of human herpesvirus (HHV)-6 and -7 in pregnant women, peripheral blood samples and genital tract secretions were collected serially from pregnant women, and both serological testing and polymerase chain reaction (PCR) were carried out to detect viral DNA in the secretions. HHV-6 or HHV-7 Immunoglobulin(Ig)M antibodies were not detected in 432 plasma samples collected from pregnant women and cord blood, but IgG antibodies against both viruses were detected in all plasma samples. Significant increases in HHV-6 and HHV-7 IgG antibodies were observed in two (1.6%) and three (2.4%) pregnant women respectively of a total of 123 cases. HHV-6 DNA was detected in the genital tract in three (3.7%) of 82 pregnant women at the first trimester, and in 10 (12.2%) of the same women in the third trimester. The detection rate in the third trimester was significantly higher than that in the first trimester (P = 0.043). Although HHV-7 DNA was detected in the genital tract of two (2.7%) and seven (9.6%) pregnant women of a total of 73 during the first and third trimesters respectively, there was no statistical difference in the detection rate of the viral DNA between the trimesters. Because a significant increase in HHV-6 IgG antibodies was detected in only two pregnant women, it was not possible to carry out statistical analysis to determine the relationship between HHV-6 infection and associated clinical features. Although there was a significant increase in HHV-7 antibody titers in three pregnant women, a positive correlation between the virus infection and the clinical features was not demonstrated. There was no statistical association between virus shedding in the genital tract and the clinical features examined in this study.

Fifth (human parvovirus) and sixth (herpesvirus 6) diseases

Fifth (erythema infectiosum) and sixth (roseola infantum) diseases are common rash illnesses of childhood that have long been recognized in clinical medicine. The discovery of the viruses that cause these illnesses has revealed relationships with other syndromes. Primary infection with the agent of erythema infectiosum, human parvovirus B19, is associated with transient aplastic crisis in hemolytic anemia, arthropathy in adults, chronic anemia in immunocompromised patients, and nonimmune fetal hydrops in pregnant women. The only documented illness associated with primary infection with human herpesvirus 6 is roseola or exanthema subitum in young children. However, reactivated infections in adults and immunocompromised patients may be associated with serious illness such as encephalitis/encephalopathy, and bone marrow suppression leading to transplant failure or graft-versus-host disease. Diagnostic studies for both viruses have been limited, although reliable serologic tests for human parvovirus B19 have recently become available. Diagnosis of human herpesvirus 6 remains problematic, because current tests cannot differentiate primary from reactivated disease. This is more of an issue for the putative relationship of these viruses to more chronic conditions, such as rheumatologic disease for human parvovirus B19 and multiple sclerosis for human herpesvirus 6. The relationship between the viruses and these conditions remains controversial, and better diagnostic tests and further information on viral pathogenesis for both viruses are required in order to make a reliable judgment in this regard.

Human herpesvirus 6: its impact and influence on infectious diseases and their management

Human herpesvirus (HHV)-6 was discovered 15 years ago and was then grouped as a member of the family human herpesviridae. Its first clinical manifestation was identified 2 years later as the agent responsible for exanthem subitum. With the advent of newer molecular techniques, its diagnosis is easier and prospective studies have shown that it is the most common pathogen responsible for febrile illness in infants. In some infants, it is associated with febrile convulsions. Two subtypes, A and B, have been identified, B subtype commonly being responsible for primary infection in infants. Primary infection in healthy adults is rare. Most of the clinical manifestations are mild, self-limiting and rarely fatal. Reactivation of HHV-6 is frequently found in bone marrow as well as solid organ transplant recipients. HHV-6 has been shown to be an independent risk factor responsible for recurrence of cytomegalovirus infection, especially in solid organ transplants. In bone marrow transplant recipients, HHV-6 has been associated with various manifestations like marrow suppression and graft versus host disease, although most infections present as usually mild febrile illness with or without rash. It has been reported to cause encephalitis in transplant recipients. Although HHV-6 has been shown to be responsible for upregulation of HIV in vitro studies, its exact role in AIDS is yet to be defined. In addition to its neurotropic manifestation of febrile convulsion in infancy, it has been found in plaques in the brain of multiple sclerosis and progressive multifocal leukoencephalopathy. Further studies are needed before its role in the pathogenesis of these neurological illnesses can be established. Its lymphotropic feature was responsible for its discovery and now it has only been detected in some lesions of primary ocular mucosa associated lymphoid tissue lymphoma. As HHV-6 is found to be responsible for more and more illnesses, especially causing serious illnesses in the immunocompromised, it is becoming necessary to find effective treatment. Some agents, like cidofovir and phosphonoformic acid, are effective in in vitro studies and some have shown effectiveness in a clinical setting. Further studies are needed to identify its role in the pathogenesis of various neurological and malignant lesions and AIDS. Various treatment regimens should be tested in clinical scenario and especially in immunocompromised transplant recipients.

Human herpesvirus-6 and -7 infections in children: agents of roseola and other syndromes

Human herpesvirus-6 (HHV-6) and -7 (HHV-7) infections typically are silent or manifested as mild febrile illnesses including classic roseola. In addition, case reports and epidemiologic data support the rare occurrence of HHV-6 encephalitis in immunocompromised as well as immunocompetent subjects. Although many other diseases have been putatively associated with HHV-6 or HHV-7, these associations are not well documented due to small numbers, use of tests incapable of distinguishing latent from replicating virus, potential virus cross-reactivity, or contradictory results. Further careful studies are needed to confirm these disease associations. Laboratory tests for diagnosing active HHV-6 and HHV-7 infections include virus culture, antigen detection, and polymerase chain reaction of cell-free biologic fluid. Although HHV-6 and HHV-7 are inhibited by several antiviral drugs in the laboratory, including ganciclovir and foscarnet, no clinical trials have assessed their benefit. Nevertheless, treatment may be considered for patients with serious HHV-6- or HHV-7-associated disease confirmed with accurate virologic tests.