Confirmation of the low clinical effect of human herpesvirus-6 and -7 infections after renal transplantation

Human herpesvirus‐6 and ‐7 (HHV‐6 and HHV‐7) may lead to pathological manifestations in renal transplant recipients. The aim of this study was to investigate beta‐herpesvirus infections in 50 adult kidney transplant recipients after transplantation to examine the effect, interactions, and pathogenic consequences of infection and the effect of immunosuppressive regimens and Human cytomegalovirus (HCMV) prophylaxis with VACV. Beta‐herpesviruses loads in the blood of 50 adult kidney transplant recipients over a 6‐month period after transplantation and 198 blood donors were determined using polymerase chain reaction. The rate of HHV‐6 detection in peripheral mononuclear cells (PBMCs) was higher in patients with end‐stage renal disease and during the post‐transplantation follow‐up than in healthy subjects (33% and 68% vs. 12%, respectively). The detection rate of HHV‐7 in PBMCs was similar between patients, both before grafting and during the follow‐up for transplant recipients (69% and 88%, respectively), and healthy subjects (78%), and correlated with the number of lymphocytes. HCMV in plasma was detected only in patients during the post‐transplant period (24%). VACV prophylaxis had no negative effect on the replication of HHV‐6 or HHV‐7, and univariate analyses demonstrated associations between HHV‐6 infection and acute graft rejection [Odds ratio (OR) = 2.94, 95% confidence interval (CI), 1.05–8.2, P = 0.04], and between HHV‐7 infection and cholestasis [OR = 2.61 (95% CI, 1.08–6.3), P = 0.03]. Immunosuppressive regimens had no effect on beta‐herpesviruses infections. This study revealed the differing behavior of HCMV, HHV‐6, and HHV‐7 in kidney transplant recipients, and confirmed the association of HHV‐6 with graft rejection. J. Med. Virol. 84:450–456, 2012. © 2011 Wiley Periodicals, Inc.     

Mapping regions of Epstein-Barr virus (EBV) glycoprotein B (gB) important for fusion function with gH/gL

Glycoproteins gB and gH/gL are required for entry of Epstein-Barr virus (EBV) into cells, but the role of each glycoprotein and how they function together to mediate fusion is unclear. Analysis of the functional homology of gB from the closely related primate gammaherpesvirus, rhesus lymphocryptovirus (Rh-LCV), showed that EBV gB could not complement Rh gB due to a species-specific dependence between gB and gL. To map domains of gB required for this interaction, we constructed a panel of EBV/Rh gB chimeric proteins. Analysis showed that insertion of Rh gB from residues 456 to 807 restored fusion function of EBV gB with Rh gH/gL, suggesting this region of gB is important for interaction with gH/gL. Split YFP bimolecular complementation (BiFC) provided evidence of an interaction between EBV gB and gH/gL. Together, our results suggest the importance of a gB-gH/gL interaction in EBV-mediated fusion with B cells requiring the region of EBV gB from 456 to 807.     

Case report: primary human herpesvirus-6 associated with an afebrile seizure in a 3-week-old infant.

We describe a 3-week-old male infant with an afebrile seizure in whom serologic and polymerase chain reaction (PCR) findings support concomitant primary human herpesvirus 6 (HHV-6) infection. Although HHV-6 infection has been associated with first-time febrile seizures and encephalitis in both immunocompetent and immunocompromised hosts, it has not been associated previously with afebrile seizures in healthy infants. This report provides additional evidence of the neuropathogenic potential of HHV-6.     

Antigenic relationships among human herpesvirus-6 isolates.

Human herpesvirus 6 (HHV-6) prototype isolate GS is a newly identified lymphotropic herpesvirus and several subsequent herpes isolates were recognized as HHV-6 by their hybridization to a HHV-6(GS) DNA probe pZVH14. DNA restriction analysis and in vitro tropism studies show that HHV-6 isolates can be divided into two groups, designated group A and group B. Antigenic relationships among 15 HHV-6 isolates belonging to these two groups were examined using rabbit antibodies against HHV-6(GS) infected cells, 11 monoclonal antibodies against three glycoproteins and four non-glycoproteins of HHV-6(GS), and sera from 136 healthy adults. More than 20 polypeptides from all these isolates were immunoprecipitated by rabbit polyclonal antibodies against HHV-6(GS) infected cells. Reactivities of monoclonal antibodies segregated these isolates into the same two groups. Group A contains HHV-6(GS), HHV-6(U1102) from a Ugandan acquired immunodeficiency syndrome (AIDS) patient, and nine other HHV-6 isolates from various disorders. HHV-6(Z-29) from a Zairian AIDS patient, HHV-6(SF) isolated from the saliva of a human immunodeficiency virus (HIV)-infected individual, HHV-6(OK) from a child with exanthem subitum, and HHV-6(DC) from a leukopenia patient are in group B. Eighty-one percent of the sera showed similar antibody titer in immunofluorescence assay with group A HHV-6(GS) and group B HHV-6(Z-29) infected cells and 19% of the sera showed two- to four-fold antibody titer differences. The mobilities of many of the polypeptides immunoprecipitated from group A HHV-6(GS) and group B HHV-6(Z-29) infected cells were different and sera showed differences in the quantities and nature of polypeptides immunoprecipitated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mathematical model to simulate the cellular dynamics of infection with human herpesvirus-6 in EBV-negative infectious mononucleosis

Acute infection with human herpesvirus-6 induces physiological cell proliferation in persons without major immune deficiency. It thus can serve as a parameter to validate a mathematical model designed to simulate cell proliferation under physiological and pathological conditions. Such a mathematical model is presented to simulate various cell changes of the T-cell immune system during the course of HHV-6 infection. Model development follows several steps, beginning with a basic model containing physiological T-cell pools to the introduction of infectious stimuli in the final model. A search algorithm designed to optimize the system parameters, as well as initial variables of the model, is presented. The results of simulation runs for acute HHV-6 infection of the final computational model correspond well to the data, as documented in human patients; they suggest that the computational model presented for the simulation of T-cell levels in a given viral infection may well serve as a tool for similar studies of other viral infections, including those that lead to cellular aplasia or neoplasia.     

Deciphering the clinical impact of acute human herpesvirus 6 (HHV-6) infections

Human herpesvirus 6 (HHV-6) is a ubiquitous virus inducing a life-long latent infection of its human host. Acute infections (AIs) have been recognized as the cause of severe diseases. These AIs correspond to primary infections (PIs), mainly occurring in young children, endogenous reactivations (ENRs), observed at any age, and putative exogenous reinfections (EXRs). The diagnosis of AIs is now essentially based on the quantification of viral load in bodily fluids and organs by means of real time PCR. However, this diagnosis is currently bothered by the lack of well established viral load thresholds for the different levels of virus replication, the concomitant infection with the two variants HHV-6A and HHV-6B, and the existence, albeit at low frequency, of chromosomal integration of viral DNA. An additional challenge is the difficulty to establish the causality relationship between AI and disease. Although many AIs are asymptomatic or poorly symptomatic with a spontaneous favourable outcome, some have been credited with serious clinical manifestations affecting central nervous system, liver, gastrointestinal tract, lungs, and bone marrow. The main favouring factor for such serious diseases is cellular immune deficiency. These severe diseases can be exemplified by encephalitis cases either associated with PI in young children or with ENR, especially in haematopoietic stem cell transplant recipients. The antiviral drugs ganciclovir, foscarnet and cidofovir have proven to be efficient against AIs and related diseases but the indications and conditions of their use are not yet formally approved. This emphasizes the need for controlled studies addressing both the clinical impact and therapy of HHV-6 AIs.     

Detection of herpesvirus-6A in a case of subacute cerebellitis and myoclonic dystonia

This is a case study of a child who developed roseola infantum first, then varicella, and was later affected by acute cerebellar syndrome, severe truncal ataxia, and myoclonic dystonia. Human herpesvirus 6 (HHV-6) A and B were detected in the cerebrospinal fluid (CSF) and peripheral blood, respectively, upon ataxia onset. The intricacy of this case suggests multifaceted conclusions ranging from the need for a multidirectional approach to neurological diseases, to confirmation of a more pronounced neurotropism of HHV-6A and a possible role of viruses in myoclonic dystonia syndrome, although this last hypothesis should be confirmed by larger studies.     

Epstein-Barr virus gH/gL has multiple sites of vulnerability for virus neutralization and fusion inhibition

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Longitudinal analysis of human cytomegalovirus glycoprotein B (gB)-specific and neutralizing antibodies in AIDS patients either with or without cytomegalovirus end-organ disease

Serum neutralizing and glycoprotein B (gB)-specific antibody levels were monitored prospectively in AIDS patients who either did or did not develop human cytomegalovirus (HCMV) end-organ disease, to delineate further the role of antibodies in protecting against HCMV disease. Antibody levels declined substantially (at least 4-fold) only in patients who developed HCMV disease; this decline in turn occurred concurrently with antigenemia. Nevertheless, AIDS patients who remained free of HCMV disease and did not become antigenemic during the follow-up period maintained stable levels of serum antibodies, with only minor fluctuations. The impact of HAART on the levels of functional anti-HCMV antibodies was investigated in a number of AIDS patients. Serum levels and kinetics of gB and neutralizing antibodies did not differ significantly between patients who responded biologically and virologically to therapy and those who failed to respond. In addition, CD4 + cell counts and HIV viral RNA levels did not correlate with anti-HCMV antibody titers.     

新生儿晚期黄疸人巨细胞病毒gB基因分型研究

目的了解引起新生儿晚期黄疸患者人巨细胞病毒（HCMV）gB基因型的分布,探讨HCMVgB基因多态性与黄疸之间的关系。结论采用荧光定量PCR法检测本院新生儿科98例晚期黄疸新生儿标本HCMV-DNA含量,巢式聚合酶链反应扩增阳性标本HCMVgB基因,并进行DNA测序,绘制种系进化树。利用HinfⅠ和RsaⅠ对gB基因进行限制性片段长度多态性（RFLP）分析。结果 30例晚期黄疸新生儿HCMV荧光定量PCR检测阳性,阳性率为30.6%。种系进化树分析结果显示gB基因分为4个基因型,gB1型15株（50%）,gB2型5株（16.7%）,gB3型9株（30.0%）,gB1/3混合型1株（3.3%）。以HCMV实验室标准株AD169作为参考,将序列进行同源性比较,gB1型同源性为94.7%～95.0%,gB2型同源性93.1%～93.4%,gB3型同源性94.7%,gB1/3型同源性93.7%。RFLP分析将gB基因分为4个基因型,分型结果与种系进化树分型一致。结论 HCMV感染是导致新生儿晚期黄疸的原因之一;gB基因的DNA序列比较保守,但仍存在一定的多态性,晚期黄疸新生儿中HCMV感染以gB1、gB3型为主。     

A case of human herpesvirus-6 lymphadenitis with infectious mononucleosis-like syndrome

The findings of a 20 year old woman with lymphadenopathy that was probably caused by an acute human herpesvirus-6 (HHV-6) infection are reported. She clinically demonstrated various signs of acute infection such as a high fever, skin rash, liver dysfunction, leukocytosis, an elevation of the erythrocyte sedimentation rate, and a positive change of C reactive protein, which mimicked the symptoms of infectious mononucleosis, but no positive titers for an Epstein-Barr virus infection were observed. HHV-6 DNA was detected using Southern blot analysis, polymerase chain reaction, and in situ hybridization in the affected node. Histologically, the lymph node showed an enlarged paracortex and infiltration of transformed lymphocytes and immunoblast-like cells with some histiocytes and eosino-phils. Almost all the transformed lymphocytes and immunoblasts were positive for UCHL-1 (CD45RO), MT-1 (CD43), and OPD-4 (CD4), and some of these positive cells demonstrated HHV-6 DNA.     

Controlled study of human herpesvirus 6 detection in acquired immunodeficiency syndrome-associated non-Hodgkin's lymphoma

Human herpesvirus 6 (HHV-6) is a recently identified lymphotropic herpesvirus, which has been isolated from patients with acquired immunodeficiency syndrome (AIDS) or lymphoproliferative diseases. Two variants A and B of HHV-6 have been described, variant B being more common in children with exanthema subitum. HHV-6 infection was studied in cases of AIDS-associated non-Hodgkin's lymphoma (NHL), and in three control populations in order to evaluate the possible etiologicai role of HHV-6 in this lymphoproliferative disease. Tumor specimens from various organs were obtained from 27 patients with AIDS-associated NHL and 20 human immunodeficiency virus (HlV)-seronegative patients with NHL. Lymph node specimens were obtained from four HIV-seropositive and nine HIV-seronegative patients with lymph node follicular hyperplasia. A specific polymerase chain reaction (PCR) was used to detect HHV-6 DNA. Subsequently HHV-6 variant was identified by using variant-specific PCR. Human cytomegalovirus (CMV) infection was detected in parallel by means of specific PCR. HHV-6 DNA was detected in 12 of 27 tumor tissues (44%), including 8 of 15 lymph node specimens (53%) from patients with AIDS-associated NHL. The corresponding values in HIV-seronegative patients with NHL were 35% (7/20) and 36% (5/14), respectively. Lymph node specimens were positive for HHV-6 in two of four (50%) HIV-seropositive and five of nine (55%) HIV-seronegative patients with follicular hyperplasia. Variant A was detected in two cases of AIDS-associated NHL, variant B in one case, and both variants in six cases. The distribution of HHV-6 variants exhibited a similar pattern in the three control groups. CMV was only detected in 3 of 27 tumor tissues (11%) from patients with AIDS-associated NHL. The prevalence of HHV-6 DNA and the distribution of its variants did not differ significantly among the four populations studied. HHV-6 was more prevalent than CMV, a closely related herpesvirus. Most cases of HHV-6 infection involved both HHV-6 variants A and B. These results do not support strongly that HHV-6 infection is closely associated with the occurrence of NHL in AIDS patients but demonstrate that mixed HHV-6 infections are more common than previously assumed. © 1995 Wiley-Liss, inc.     

Genotypic analysis of two hypervariable human cytomegalovirus genes

Most human cytomegalovirus (HCMV) genes are highly conserved in sequence among strains, but some exhibit a substantial degree of variation. Two of these genes are UL146, which encodes a CXC chemokine, and UL139, which is predicted to encode a membrane glycoprotein. The sequences of these genes were determined from a collection of 184 HCMV samples obtained from Africa, Australia, Asia, Europe, and North America. UL146 is hypervariable throughout, whereas variation in UL139 is concentrated in a sequence encoding a potentially highly glycosylated region. The UL146 sequences fell into 14 genotypes, as did all previously reported sequences. The UL139 sequences grouped into 8 genotypes, and all previously reported sequences fell into a subset of these. There were minor differences among continents in genotypic frequencies for UL146 and UL139, but no clear geographical separation, and identical nucleotide sequences were represented among communities distant from each other. The frequent detection of multiple genotypes indicated that mixed infections are common. For both genes, the degree of divergence was sufficient to preclude reliable sequence alignments between genotypes in the most variable regions, and the mode of evolution involved in generating the genotypes could not be discerned. Within genotypes, constraint appears to have been the predominant mode, and positive selection was detected marginally at best. No evidence was found for linkage disequilibrium. The emerging scenario is that the HCMV genotypes developed in early human populations (or even earlier), becoming established via founder or bottleneck effects, and have spread, recombined and mixed worldwide in more recent times.     

Human herpesvirus-6 infection: a prospective study evaluating HHV-6 DNA levels in liver from children with acute liver failure

The aim of this prospective study was to investigate the role of HHV-6 infection in children with acute onset of liver failure using real-time quantitative PCR. Twenty-three children (median age, 24 months) were included: 6 cases of fulminant hepatic failure of undetermined cause (group 1); 4 cases of fulminant hepatic failure of recognized cause (group 2); 3 cases of acute decompensation of chronic liver disease (group 3); and 10 cases of chronic liver disease (group 4). HHV-6 genomic DNA was detected and quantified using real-time PCR in plasma and livers obtained at the time of transplantation. HHV6-DNA detection rate was significantly higher among groups 1, 2, and 3 compared to group 4 (76.9% vs. 20% P = 0.02). Viral loads ranged from 6 to 32,500 copies/106 cells. Significantly higher viral loads were found in 4 of 9 children with acute onset of liver failure of unknown origin (group 1, n = 3; group 3, n = 1) and 1 child with fulminant autoimmune hepatitis (group 2) (P = 0.03). These results strongly support the hypothesis that HHV-6 may cause fulminant hepatic failure and acute decompensation of chronic liver disease in children. Nevertheless, a threshold viral load value still remains to be determined.     

Analysis of human herpesvirus-6 IE1 sequence variation in clinical samples

Herpesvirus immediate early (IE) proteins are known to play key roles in establishing productive infections, regulating reactivation from latency, and creating a cellular environment favourable to viral replication. Human herpesvirus-6 (HHV-6) IE genes have not been studied as intensively as their homologues in the prototype betaherpesvirus human cytomegalovirus (HCMV). Whilst the HCMV IE1 gene is relatively conserved, early studies indicated that HHV-6 IE1 exhibited a high level of sequence variation between HHV-6A and HHV-6B isolates, although the observation was based primarily on virus stocks that had been isolated and propagated in vitro. In this study, we investigated the level of HHV-6 IE1 sequence variation in vivo by direct sequencing of circulating virus in clinical samples without prior in vitro culture. Sequences exactly matching those reported for reference HHV-6 isolates were identified in clinical samples, thus the HHV-6 laboratory strains used in the majority of in vitro studies appear to be representative of virus circulating in vivo with respect to the IE1 gene. The HHV-6 IE1 sequence is also conserved in reference strains that had been passaged extensively in vitro. The high degree of divergence between variant A and B type IE1 sequences was confirmed, but interestingly HHV-6B IE1 sequences were observed to further segregate into two distinct subgroups, with the laboratory strains Z29 and HST representative of these two subgroups. Within each HHV-6B subgroup, a remarkably high level of homology was observed. Thus the HHV-6 IE1 sequence appears highly stable, underlining its potential importance to the viral life cycle.     

A serological investigation of human herpesvirus 6 infections in liver transplant recipients and the detection of cross-reacting antibodies to cytomegalovirus.

Sera from 50 orthotopic liver transplant recipients were examined for antibodies to human herpesvirus 6 (HHV-6) and cytomegalovirus (CMV), and the findings correlated with the clinical condition of the patients. Both primary and secondary HHV-6 infections were detected serologically following liver transplantation. Interpretation of serological assays is complicated by CMV and HHV-6 antibody cross reactions which were common. Sera from 5 patients became HHV-6 antibody negative following absorption with CMV infected cells. Thirty patients were initially seronegative for HHV-6 antibodies, 12 remained so following transplantation, 5 developed cross reacting antibodies, and 13 seroconverted. The seroconversions occurred at 4 to 8 weeks post-transplant in the same time period as CMV antibody rises. HHV-6 IgM was detected in only 4 of the 13. Of the 7 patients who had serological evidence of active HHV-6 infections but no evidence of CMV infection, 4 (56%) had fever, 1 (14%) hepatitis, 1 (14%) lung dysfunction, and 3 (42%) neurological disorders. In the 12 patients who remained HHV-6 antibody negative, there were fewer fevers and neurological disorders.     

Infection of a human retinal pigment epithelial cell line with human herpesvirus 6 variant A

A retinal pigment epithelial (RPE) cell line (K-1034) was examined for its susceptibility to human herpesvirus 6 variant A (HHV-6A). Exposure of K-1034 cells to HHV-6A induced the formation of multinucleated giant cells, which was suppressed by an inhibitor of viral DNA synthesis. In the giant cells, herpesvirus nucleocapsids were demonstrated by electron microscopy and the viral glycoprotein B was detected by immunofluorescence assay. These results indicate that K-1034 cells are susceptible to HHV-6A and suggest that HHV-6A has an ability to directly destroy epithelial cells. J. Med. Virol. 53:105–110, 1997. © 1997 Wiley-Liss, Inc.