Human herpesvirus-6 infection in liver transplantation

Rejection and infections are the two most common complications after liver transplantation. Human herpesvirus-6 (HHV-6) belongs to the betaherpesviruses, together with its close relatives cytomegalovirus (CMV) and human herpesvirus-7 (HHV-7). The impact of CMV in liver transplantation is well characterized, but the roles of the other two betaherpesviruses have been acknowledged only recently. Although, HHV-6 reactivation after transplantation is usually asymptomatic, the virus may infect the liver transplant, cause an intragraft lymphocyte dominated inflammatory reaction and graft dysfunction. HHV-6 is also suggested to be associated with liver allograft rejection but the mechanisms are unclear. The aim of this study was to investigate the intragraft immunological processes associated with HHV-6, the involvement of HHV-6 in acute liver failure (ALF) and the hepatic HHV-6 infection of the same patients after transplantation. In addition, the occurrence of HHV-6 and HHV-7 was investigated in liver transplant patients with symptomatic CMV infection. HHV-6 infection of the liver graft was associated with portal lymphocyte infiltration and with a significant increase of adhesion molecules (ICAM-1 and VCAM-1) and the number of cells expressing their ligand molecules (LFA-1, VLA-4) and class II antigens. HHV-6 infection was associated with significant immunological changes, but the immune response was limited to lymphocyte infiltration and the adhesion molecule level. However, one third of these patients developed chronic rejection during the follow-up. Of the patients with ALF of unknown origin, most patients demonstrated HHV-6 antigens in the liver, whereas the opposite was seen in ALF patients with a known disease. After transplantation, HHV-6 recurrence was found in the liver transplant in half of these patients with pre-transplant HHV-6 infection of the liver, whereas no post-transplant HHV-6 infection of the liver was seen in patients without pre-transplant HHV-6. Our studies further demonstrated that both HHV-6 and HHV-7 antigenemia often appeared in association with CMV disease in liver transplant patients. The time-related occurrence of the viruses differed, as HHV-6 appeared early after transplantation and regularly preceded CMV whereas HHV-7 often appeared concurrently with CMV. In conclusion, these results indicate that all three betaherpesviruses are common after liver transplantation, often associated with each other. The immunological events caused by HHV-6 in the liver transplant may be involved in, or trigger mechanisms of allograft rejection. In addition, HHV-6 could be one of the causes of ALF, and pre-transplant HHV-6 infection in ALF patients is a risk factor for post-transplant HHV-6 infection of the graft. These results strongly support the clinical significance of HHV-6 in liver transplantation. Even though the reactivation is usually asymptomatic, in some individuals HHV-6 infection may lead to severe manifestations, such as liver failure or in transplant patients, graft dysfunction and rejection.Hylkimisreaktio ja infektiot ovat maksansiirtopotilaiden merkittävimpiä komplikaatioita. Ihmisen herpesvirus-6 (HHV-6) aiheuttaa vauvarokon varhaislapsuudessa, jää muiden herpesvirusten tavoin primääri-infektion jälkeen elimistöön piilevänä ja voi aktivoitua elinsiirron yhteydessä. HHV-6 kuuluu beetaherpesviruksiin yhdessä läheisten sukulaistensa cytomegaloviruksen (CMV) ja ihmisen herpesvirus-7:n (HHV-7) kanssa. CMV:n merkitys suorien ja epäsuorien komplikaatioiden aiheuttajana elinsiirtopotilailla on tunnettu, mutta HHV-6:n ja HHV-7:n merkityksestä tiedetään vähemmän. Useimmiten HHV-6:n aktivoituminen maksansiirtopotilailla tapahtuu oireitta, mutta virus voi myös infektoida elinsiirrännäisen, huonontaa siirrännäisen toimintaa ja aiheuttaa tulehdusreaktion. HHV-6:n uskotaan olevan yhteydessä hylkimisreaktioon, mutta tutkimustieto aiheesta on rajallista ja vaikutustapa epäselvä. Tämän väitöskirjatutkimuksen tarkoituksena oli tutkia maksasiirteen immunologisia tapahtumia HHV-6 infektion yhteydessä, HHV-6:n yhteyttä tuntemattomasta syystä aiheutuneeseen äkilliseen maksan vajaatoimintaan, ja samojen potilaiden uuden maksan infektoitumista HHV-6:lla. Lisäksi tutkittiin HHV-6:n ja HHV-7:n esiintymistä oireisen CMV-infektion yhteydessä maksansiirron jälkeen. HHV-6 infektion todettiin olevan yhteydessä maksasiirteen lisääntyneeseen tulehdusreaktioon ja merkittäviin immunologisiin muutoksiin, vaikkei potilailla todettu samanaikaista hylkimisreaktiota. Tutkimuksessa todettiin kuitenkin useiden immunoaktivaatioon liittyvien, myös hylkimiselle tyypillisten, molekyylien lisääntynyttä esiintymistä maksasiirteessä. Kolmanneksella näistä potilaista havaittiin myöhemmin krooninen hylkiminen. Äkillisen maksan vajaatoiminnan syy jää lähes puolella potilaista epäselväksi. Suurimmalla osalla näistä potilaista voitiin osoittaa HHV-6 maksassa, kun taas tunnetun syyn ryhmässä HHV-6 oli harvinainen. Maksansiirron jälkeen HHV-6 aiheutti uuden maksan infektion puolella potilaista, joilla ennen siirtoa oli HHV-6, muttei yhdelläkään niistä potilaista, joilla sitä ei ollut ennen siirtoa. Kaikki kolme beetaherpesvirusta esiintyivät yleisesti maksansiirron jälkeen ja usein myös yhdessä. Ajallisesti esiintymiset kuitenkin erosivat: HHV-6 esiintyi ensimmäisenä keskimäärin pari viikkoa maksansiirron jälkeen, kun taas CMV ja HHV-7 esiintyivät usein samanaikaisesti HHV-6:a myöhemmin. Beetaherpesvirusten aktivaatio on yleistä maksansiirron jälkeen ja kaikki kolme virusta ilmenevät usein samanaikaisesti. Immunologiset tapahtumat, joita HHV-6 maksasiirteessä aiheuttaa, saattavat olla yhteydessä hylkimisreaktion kehittymiseen tai altistaa sille. HHV-6 saattaa olla yksi äkillisen maksan vajaatoiminnan syistä, ja altistaa maksasiirteen infektoitumiseen samoilla potilailla. Tulokset vahvistavat käsitystä, että vaikka HHV-6 aktivaatio on useimmilla maksansiirtopotilailla oireeton se johtaa joillain yksilöillä vakavampiin ilmenemismuotoihin, kuten maksan vajaatoimintaan tai lisääntyneeseen hylkimistaipumukseen

Early diagnosis of primary human herpesvirus 6 infection in childhood: Serology, polymerase chain reaction, and virus load

Qualitative and quantitative polymerase chain reaction (PCR) for human herpesvirus 6 (HHV-6) DNA in whole blood and plasma was correlated with serology and clinical assessment in 143 children hospitalized for undifferentiated febrile illness to evaluate options for diagnosis of primary HHV-6 infection on the acute blood specimen. PCR and serology for HHV-7 were done in parallel to define serologic cross-reactions. Using HHV-6 seroconversion as the reference standard, detection of HHV-6 DNA in whole blood in the absence of antibody in the plasma was the most reliable evidence of primary HHV-6 infection. Detection of HHV-6 DNA in plasma and a high virus load in whole blood (>3.3 log 10 copies/5 μL) had a sensitivity of 90% and 100%, respectively, in diagnosing primary HHV-6 infection. However, both were occasionally found in patients with other infections, possibly associated with HHV-6 reactivation. Maternal antibody may confound interpretation of serology in patients under 3 months of age.published_or_final_versio

An Assessment of the Effect of Human Herpesvirus-6 Replication on Active Cytomegalovirus Infection after Allogeneic Stem Cell Transplantation

Human herpesvirus-6 (HHV-6) may enhance cytomegalovirus (CMV) replication in allogeneic stem cell transplant (allo-SCT) recipients either through direct or indirect mechanisms. Definitive evidence supporting this hypothesis are lacking. We investigated the effect of HHV-6 replication on active CMV infection in 68 allo-SCT recipients. Analysis of plasma HHV-6 and CMV DNAemia was performed by real-time PCR. Enumeration of pp65 and IE-1 CMV-specific IFNγ CD8+ and CD4+T cells was performed by intracellular cytokine staining. HHV-6 DNAemia occurred in 39.8% of patients, and was significantly associated with subsequent CMV DNAemia in univariate (P=.01), but not in multivariate analysis (P=.65). The peak of HHV-6 DNAemia was not predictive of the development of CMV DNAemia. Timing and kinetics of active CMV infection were comparable in patients either with or without a preceding episode of HHV-6 DNAemia. The occurrence of HHV-6 DNAemia had no impact on CMV-specific T cell immunity reconstitution early after transplant. The receipt of a graft from an HLA-mismatched donor was independently associated with HHV-6 (P=.009) and CMV reactivation (P=.04). The data favor the hypothesis that a state of severe immunosuppression leads to HHV-6 and CMV coactivation, but argue against a role of HHV-6 in predisposing to the development of CMV DNAemia or influencing the course of active CMV infection

Human herpesvirus 6 infection impairs Toll-like receptor signaling

Human herpesvirus 6 (HHV-6) has a tropism for immunocompetent cells, including T lymphocytes, monocytes/macrophages, and dendritic cells (DCs) suggesting that HHV-6 infection affects the immunosurveillance system. Toll-like receptor (TLR) system plays an important role in innate immunity against various pathogens. In the present study, we investigated the effect of HHV-6 infection on the expression and intracellular signaling of TLRs in DCs. Although expression levels of TLRs were not decreased or slightly elevated following HHV-6 infection, the amounts of cytokines produced following stimulation with ligands for TLRs appeared to be dramatically decreased in HHV-6-infected DCs as compared to mock-infected DCs. Similarly, phosphorylation levels of TAK-1, IκB kinase, and IκB-α following stimulation of HHV-6-infected DCs with lipopolysaccharide, which is the ligand for TLR4, appeared to be decreased. These data show that HHV-6 impairs intracellular signaling through TLRs indicating the novel mechanism of HHV-6-mediated immunomodulation

Human herpesvirus-6 viral load and antibody titer in serum samples of patients with multiple sclerosis

BackgroundDespite the number of cases with definite diagnosis of multiple sclerosis (MS) being on increase, the role of human herpesvirus-6 (HHV-6) infection as a trigger for MS disease still is deliberated. Based on antibody detection and quantitative HHV-6 polymerase chain reaction assay, this study was achieved to find out the possible association between infection with HHV-6 and clinical progression of MS disease.MethodsA total of 108 serum samples were obtained from 30 MS patients followed prospectively for a 6-month period. These samples were analyzed for the presence of HHV-6 DNA by nested polymerase chain reaction enzyme-linked immunosorbent assay and for anti-HHV-6 IgG titer. Activation of the disease was determined by either magnetic resonance imaging or by clinical status of the patients. Control groups were also included.ResultsThe average antibody index for the MS patients in the first sample collection was higher than both control groups (p = 0.001). HHV-6 DNA was detected in the serum samples of 10 of 30 MS patients. The mean HHV-6 viral load in patients with relapsing-remitting multiple sclerosis (RRMS) with and without relapse was 973 and 714, respectively. Seven patients showed an exacerbation during the study period. Of those, four patients had HHV-6 DNA in their collected samples. The prevalence of HHV-6 DNA was significantly higher in patients with MS as compared with control groups (p = 0.001).ConclusionsThe results indicate that HHV-6 is implicated somehow in MS disease. Over time, rising HHV-6 IgG antibody titers together with an exacerbation and detection of HHV-6 DNA in serum samples of some MS patients suggests possible association between the reactivation of the virus and disease progression

Human herpesvirus 6 major immediate early promoter has strong activity in T cells and is useful for heterologous gene expression

<p>Abstract</p> <p>Background</p> <p>Human herpesvirus-6 (HHV-6) is a beta-herpesvirus. HHV-6 infects and replicates in T cells. The HHV-6-encoded major immediate early gene (MIE) is expressed at the immediate-early infection phase. Human cytomegalovirus major immediate early promoter (CMV MIEp) is commercially available for the expression of various heterologous genes. Here we identified the HHV-6 MIE promoter (MIEp) and compared its activity with that of CMV MIEp in various cell lines.</p> <p>Methods</p> <p>The HHV-6 MIEp and some HHV-6 MIEp variants were amplified by PCR from HHV-6B strain HST. These fragments and CMV MIEp were subcloned into the pGL-3 luciferase reporter plasmid and subjected to luciferase reporter assay. In addition, to investigate whether the HHV-6 MIEp could be used as the promoter for expression of foreign genes in a recombinant varicella-zoster virus, we inserted HHV-6 MIEp-DsRed expression casette into the varicella-zoster virus genome.</p> <p>Results</p> <p>HHV-6 MIEp showed strong activity in T cells compared with CMV MIEp, and the presence of intron 1 of the MIE gene increased its activity. The NF-κB-binding site, which lies within the R3 repeat, was critical for this activity. Moreover, the HHV-6 MIEp drove heterologous gene expression in recombinant varicella-zoster virus-infected cells.</p> <p>Conclusions</p> <p>These data suggest that HHV-6 MIEp functions more strongly than CMV MIEp in various T-cell lines.</p

Dominance of variant A in Human Herpesvirus 6 viraemia after renal transplantation

<p>Abstract</p> <p>Background</p> <p>Human herpesvirus 6 (HHV-6), mostly variant B reactivation in renal transplant patients has been published by other authors, but the pathogenetic role of HHV-6 variant A has not been clarified. Our aims were to examine the prevalence of HHV-6, to determine the variants, and to investigate the interaction between HHV-6 viraemia, human cytomegalovirus (HCMV) infection and clinical symptoms.</p> <p>Methods</p> <p>Variant-specific HHV-6 nested PCR and quantitative real-time PCR were used to examine blood samples from renal transplant patients and healthy blood donors for the presence and load of HHV-6 DNA and to determine the variants. Active HHV-6 infection was proved by RT-PCR, and active HCMV infection was diagnosed by pp65 antigenaemia test.</p> <p>Results</p> <p>HHV-6 viraemia was significantly more frequent in renal transplant patients compared to healthy blood donors (9/200 vs. 0/200; p = 0.004), while prevalence of HHV-6 latency was not significantly different (13/200 vs. 19/200; p > 0.05). Dominance of variant A was revealed in viraemias (8/9), and the frequency of HHV-6A was significantly higher in active infections compared with latency in renal transplant patients (8/9 vs. 2/13; p = 0.0015). Latency was established predominantly by HHV-6B both in renal transplant patients and in healthy blood donors (11/13 and 18/19). There was no statistical significant difference in occurrence of HCMV and HHV-6 viraemia in renal transplant patients (7/200 vs. 9/200). Statistical analysis did not reveal interaction between HHV-6 viraemia and clinical symptoms in our study.</p> <p>Conclusions</p> <p>Contrary to previous publications HHV-6A viraemia was found to be predominant in renal transplant patients. Frequency of variant A was significantly higher in cases of active infection then in latency.</p

Endogenization and excision of human herpesvirus 6 in human genomes

Sequences homologous to human herpesvirus 6 (HHV-6) are integrated within the nuclear genome of about 1% of humans, but it is not clear how this came about. It is also uncertain whether integrated HHV-6 can reactive into an infectious virus. HHV-6 integrates into telomeres, and this has recently been associated with polymorphisms affecting MOV10L1. MOV10L1 is located on the subtelomere of chromosome 22q (chr22q) and is required to make PIWI-interacting RNAs (piRNAs). As piRNAs block germline integration of transposons, piRNA-mediated repression of HHV-6 integration has been proposed to explain this association.In vitro, recombination of the HHV-6 genome along its terminal direct repeats (DRs) leads to excision from the telomere and viral reactivation, but the expected "solo-DR scar" has not been describedin vivo. Here we screened for integrated HHV-6 in 7,485 Japanese subjects using whole-genome sequencing (WGS). Integrated HHV-6 was associated with polymorphisms on chr22q. However, in contrast to prior work, we find that the reported MOV10L1 polymorphism is physically linked to an ancient endogenous HHV-6A variant integrated into the telomere of chr22q in East Asians. Unexpectedly, an HHV-6B variant has also endogenized in chr22q; two endogenous HHV-6 variants at this locus thus account for 72% of all integrated HHV-6 in Japan. We also report human genomes carrying only one portion of the HHV-6B genome, a solo-DR, supporting in vivo excision and possible viral reactivation. Together these results explain the recently-reported association between integrated HHV-6 and MOV10L1/piRNAs, suggest potential exaptation of HHV-6 in its coevolution with human chr22q, and clarify the evolution and risk of reactivation of the only intact (non-retro)viral genome known to be present in human germlines

Assessing putative interplay between human herpesvirus-6 infection and alcohol abuse in substantia nigra

The previous studies have demonstrated that the central nervous system (CNS) is particularly vulnerable to alcohol induced changes, for example, alcohol increases the risk of Parkinson’s disease by affecting Substantia nigra (SN). Also called the “Black Substance”, it is the dopaminergic neurons rich part of the basal ganglia located in the midbrain. Human herpesvirus-6 (HHV-6) is a linear double stranded DNA virus; infection is ubiquitous and can induce various neurological diseases. HHV-6 replicates most efficiently in activated primary T cells, however, studies show that the virus can also replicate in a wide array of host cells, for example in monocytes, macrophages, astrocytes, oligodendrocytes and neurons. The aim of the study is to detect the presence of HHV-6 in SN region of chronic alcoholics and healthy individuals. Post mortem tissue samples of SN grey and white matter from 42 individuals (control group, age matched alcoholics and non-age matched alcoholics) were analysed in this study. DNA was extracted using black PREP FFPE DNA kit. To detect viral genomic sequences and variant, we were using nPCR technique. Viral loads were detected using HHV-6 Real-TM Quant kit. Fluorescent immunehistochemical staining and confocal microscopy were applied. The presence of HHV-6 DNA was detected in 19, 05% (8/42) of the SN region. All positive HHV-6 FFPE tissue samples were from alcoholic individuals. In white matter HHV-6 was detected in 62, 5% (5/8), and in grey matter – 87,5% (7/8) out of HHV-6 positive cases. All control individuals were HHV-6 negative. HHV-6B variant was detected in all positive individuals. Viral load was detected in the one alcoholic individuals’ white matter – 101207, 97 copies/1x106 cells.HHV-6 immunopositivity was detected in both grey and white matter. These findings provide evidence that HHV-6 can integrate and replicate in the SN region. In addition, the evidence from this study shows then the potential role of HHV-6 and alcohol use may affect brain homeostasis.publishersversionPeer reviewe

Effect of Human Herpesviruses 6 and 7 Infection on the Clinical Course of Rheumatoid Arthritis

Publisher Copyright: © 2016 by Anda Kadiša. Copyright: Copyright 2018 Elsevier B.V., All rights reserved.Rheumatoid arthritis (RA) is a chronic systemic autoimmune inflammatory disease affecting joints and causing symmetrical chronic progressive aseptic synovitis and erosive-destructive changes. Viruses and viral infections are considered to be the main risk factors for autoimmune disease development (especially for individuals with genetic predisposition). The goal of this study was to evaluate the frequency of HHV-6 and HHV-7 persistent infection and its activity phase in RA and osteoarthritis (OA) patients, and healthy persons. We examined also the influence of HHV-6 and-7 infections on RA activity, aggressiveness, radiographical stage, and frequency of complications as well as the presence of HHV-6 infection markers in synovial fluid and synovial tissues of RA joints of affected patients. Despite the lack of significant correlation between frequency of persistent single HHV-6, single HHV-7, and concurrent HHV-6 and HHV-7 infection and RA clinical course, we found that both active and latent HHV-6 and/or HHV-7 infection increased RA activity and progression in several clinical and laboratory parameters. Regarding the severity of the course of RA, we observed also a high prevalence of RA complications in the patient group with active single HHV-6 infection and also a more severe radiographical stage in RA patients with active concurrent HHV-6 and HHV-7 infection. Moreover, viral infection markers were found in synovial fluid and synovial tissues of affected joints of RA patients. This suggests that HHV-6 and/or HHV-7 infection has effect on the disease clinical course, but virus reactivation may be a consequence of immunosuppressive treatment.Peer reviewe