HHV-6 in liver transplantation : A literature review

Human herpesvirus 6 (HHV-6A and HHV-6B) can cause primary infection or reactivate from latency in liver transplant recipients, which can result in a variety of clinical syndromes, including fever, hepatitis, encephalitis and higher rates of graft dysfunction as well as indirect effects including increased risks of mortality, CMV disease, hepatitis C progression and greater fibrosis scores. Although HHV-6 infection is currently diagnosed by quantifying viral DNA in plasma or blood, biopsy to demonstrate histopathological effects of HHV-6 remains the gold standard for diagnosis of end-organ disease. HHV-6 reactivation may be restricted to the infected organ with no evidence of active infection in the blood. HHV-6 infections in liver transplant patients are mostly asymptomatic, but clinically significant tissue-invasive infections have been treated successfully with ganciclovir, foscarnet or cidofovir. Inherited chromosomally integrated HHV-6 (ciHHV-6), in either the recipient or the donor organ, may create confusion about systemic HHV-6 infection. Recipients with inherited ciHHV-6 may have an increased risk of opportunistic infection and graft rejection. This article reviews the current scientific data on the clinical effects, risk factors, pathogenesis, diagnosis and treatment of HHV-6 infections in liver transplant recipients.Peer reviewe

Distribution of the major histocompatibility complex antigens in human and rat kidney

Distribution of the major histocompatibility complex antigens in human and rat kidney. We have compared the distribution of the major histocompatibility complex (MHC) antigens in human and rat kidney using monospecific antisera to class I and II antigens of the MHC. FITC/TRITC double immunofluorescence was used to demonstrate these antigens in frozen sections and the Staphylococcus aureus Cowan I rosette assay on the cell surface. In both species, the MHC antigens were prominently present on the passenger leukocytes. Immunofluorescence analysis of human kidney demonstrated that the class I, β2-microglobulin (β2m), and class II antigens were present in the vascular endothelial cells and class I antigens in the renal tubular cells. The Staphylococcus assay demonstrated that these antigens were also exposed on the respective cell surfaces. In clear contrast, in the rat, class I, the β2m, and class II antigens were absent from the kidney vascular endothelium of large vessels and intertubular capillaries; however, large amounts of class II antigens were seen inside the proximal renal tubular cells. The Staphylococcus assay indicated that none or very little of these antigens were exposed on the kidney parenchymal cell surface. These differences may explain why rat renal transplants are relatively non-immunogenic and easily accepted, whereas human renal transplant recipients must be immunosuppressed ad infinitum.Distribution des antigènes du complexe d'histocompatibilité principal du rein d'homme et de rat. Nous avons comparé la distribution des antigènes du complexe d'histocompatibilité principal (MHC) dans du rein d'homme et de rat en utilisant des antisérums monospécifiques des antigènes des classes I et II du MHC. Une double immunofluorescence FITC/TRITC a été utilisée pour démontrer ces antigènes dans des sections congelées et le dosage des rosettes de Staphylocoque doré Cowan I pour les démontrer à la surface cellulaire. Dans les deux espèces, les antigènes MHC étaient essentiellement présents sur les leucocytes de passage. L'analyse en immunofluorescence de rein humain a démontré que les antigènes de classe I, 1 β2-microglobuline (β2m) et de classe II étaient présents dans les cellules endothéliales vasculaires, et ceux de classe I dans les cellules tubulaires rénales. Le dosage Staphylocoque a démontré que ces antigènes étaient également exposés sur les surfaces cellulaires respectives. De facon clairement opposée, chez le rat, les antigènes de classe I, 1 β2m et de classe II étaient absents de l'endothélium vasculaire rénal des gros vaisseaux et des capillaires intertubulaires; cependant, de grandes quantités d'antigènes de classe II étaient visibles à l'intérieur des cellules tubulaires rénales proximales. L'essai Staphylocoque a indiqué qu'aucun ou très peu de ces antigènes étaient exposés à la surface des cellules parenchymateuses rénales. Ces différences pourraient expliquer pourquoi les greffons rénaux de rat sont relativement non immunogènes et facilement tolérés, alors que les receveurs de transplants rénaux humains doivent être immunodéprimés indéfiniment

An International Multicenter Performance Analysis of Cytomegalovirus Load Tests

A new quantitative polymerase chain reaction assay, COBAS AmpliPrep/COBAS TaqMan CMV Test, was developed using the first World Health Organization cytomegalovirus standard. It demonstrated a high level of interlaboratory agreement and precision compared to quantitative results obtained with tests used by 5 different laboratorie

BK polyomavirus microRNA expression and sequence variation in polyomavirus-associated nephropathy

Background: BK polyomavirus (BKPyV) infection is a common asymptomatic viral infection in the general population. Severe complications are seen in immunocompromised individuals, such as polyomavirus-associated nephropathy (PyVAN) in renal transplant recipients. Information on BKPyV microRNA expressions is scarce, although polyomavirus-encoded microRNAs have been shown to control viral replication and assist in immune evasion. Whereas the pathogenic role of rearrangements in JC polyomavirus has been well established, little is known about BKPyV rearrangements in PyVAN. Objectives: To assess viral microRNA expression and transcriptional control region (TCR) sequence variation in PyVAN patients. Study design: bkv-miR-B1-3p and bkv-miR-B1-5p microRNA expression was quantified in 55 plasma samples from 9 PyVAN patients and 2 controls using specific miRNA assays. TCR architectures among the viral populations in each patient were characterized by massive parallel sequencing. Results: bkv-miR-B1-3p and bkv-miR-B1-5p miRNA expression was established in 85.5% and 98.2% of samples, respectively. On average, an 8.9-fold (bkv-miR-B1-3p) and 8.7-fold (bkv-miR-B1-5p) higher expression levels were detected in PyVAN patients as compared to controls. Rearranged BKPyV strains with duplications and deletions were detected in 7/9 PyVAN patients, but 77.6-99.9% of all sequence reads in all samples represented archetype strains. Conclusions: The frequent detection and increased expression of miRNAs suggest involvement in PyVAN pathogenesis. Despite the predominance of archetype BKPyV strains, the frequent detection of minor rearranged viral populations urges further study on their role in severe kidney disease. Our results suggest that miRNA expression is increased in PyVAN patients, as well as in the presence of rearranged viral strains.Peer reviewe

Cytomegalovirus sequence variability, amplicon length, and DNase-sensitive non-encapsidated genomes are obstacles to standardization and commutability of plasma viral load results

Background: Cytomegalovirus (CMV) management post-transplantation relies on quantification in blood, but inter-laboratory and inter-assay variability impairs commutability. An international multicenter study demonstrated that variability is mitigated by standardizing plasma volumes, automating DNA extraction and amplification, and calibration to the 1st-CMV-WHO-International-Standard as in the FDA-approved Roche-CAP/CTMCMV. However, Roche-CAP/CTM-CMV showed under-quantification and false-negative results in a quality assurance program (UK-NEQAS-2014). Objectives: To evaluate factors contributing to quantification variability of CMV viral load and to develop optimized CMV-UL54-QNAT. Study design: The UL54 target of the UK-NEQAS-2014 variant was sequenced and compared to 329 available CMV GenBank sequences. Four Basel-CMV-UL54-QNAT assays of 361 bp, 254 bp, 151 bp, and 95 bp amplicons were developed that only differed in reverse primer positions. The assays were validated using plasmid dilutions, UK-NEQAS-2014 sample, as well as 107 frozen and 69 prospectively collected plasma samples from transplant patients submitted for CMV QNAT, with and without DNase-digestion prior to nucleic acid extraction. Results: Eight of 43 mutations were identified as relevant in the UK-NEQAS-2014 target. All Basel-CMV-UL54 QNATs quantified the UK-NEQAS-2014 but revealed 10-fold increasing CMV loads as amplicon size decreased. The inverse correlation of amplicon size and viral loads was confirmed using 1st-WHO-International-Standard and patient samples. DNase pre-treatment reduced plasma CMV loads by > 90% indicating the presence of unprotected CMV genomic DNA. Conclusions: Sequence variability, amplicon length, and non-encapsidated genomes obstruct standardization and commutability of CMV loads needed to develop thresholds for clinical research and management. Besides regular sequence surveys, matrix and extraction standardization, we propose developing reference calibrators using 100 bp amplicons.Peer reviewe

Simultaneous BK Polyomavirus (BKPyV)-associated nephropathy and hemorrhagic cystitis after living donor kidney transplantation

BK polyomavirus (BKPyV) commonly reactivates after kidney transplantation, and can cause polyomavirus-associated nephropathy (PyVAN), whereas after allogeneic stem cell transplantation the most frequent manifestation of BKPyV is polyomavirus-associated hemorrhagic cystitis (PyVHC). Despite high-level BKPyV replication in both, the pathogenesis and manifestation of both BKPyV entities appears to differ substantially. We describe an unusual case of simultaneous PyVAN and PyVHC presenting with acute symptoms in a BKPyV-IgG positive recipient eight months after kidney transplantation from a haploidentical living donor, who was BKPyV-IgG negative. Symptoms of cystitis and viremia subsided rapidly after reduction of immunosuppression. (C) 2015 Elsevier B.V. All rights reserved.Peer reviewe

Cytomegalovirus infection of human kidney cells in vitro

Cytomegalovirus infection of human kidney cells in vitro. To study which structures of a kidney allograft are the main targets for cytomegalovirus (CMV), human glomerular epithelial and mesangial cells, as well as tubular epithelial and endothelial cells were isolated by steel meshes of different pore sizes and enzymatic treatments. The various cultured cell types were characterized by morphology and specific antibodies. Human CMV was inoculated onto cell monolayers using two different culture methods: conventional tissue culture and rapid shell vial culture. To analyze whether CMV had a direct effect on the immunologic properties of kidney parenchymal cells, MHC class I and class II antigen expression was estimated before and after the infection. CMV infected all kidney cells identically. All cells expressed class I strongly after the infection, but they were class I positive prior to infection. Class II antigens were not expressed on the cell surface either before or after the infection. In conclusion, human kidney cells of glomerular, tubular and vascular origin were all infected by CMV without any difference. CMV had no significant direct effects on the antigenic properties of the cells

High-level JCPyV viruria after kidney transplantation-Clinical and histopathological findings

Background:The significance of JC polyomavirus (JCPyV) after kidney transplantation ranges from irrelevant to full-blown nephropathy or PML. Objectives: To investigate the clinical significance of high-level JCPyV viruria and JCPyV primary infections after kidney transplantation. Study design: JCPyV viruria was detected in routine screening by quantitative real-time PCR in 40/238 kidney transplant recipients and was high-level (> 10(7)copies/ml) in 17 patients. A protocol biopsy at the time of JCPyV viruria was available from 10 patients. Results: Peak urine viral loads were 1.0 x 10(7)-2.5 x 10(9)copies/ml in the 17 high-level viruria patients. 6/15 (40%) patients with high-level JCPyV viruria with pretransplant sera available were JCPyV IgG negative suggesting that JCPyV viruria resulted from the donor graft in most cases. No acute graft dysfunction was associated with JCPyV viruria. No positive SV40 staining was detected in protocol biopsies, and nospecific histopathology was associated with high-level viruria; JCPyV nephropathy was not found. No differences were seen in histopathology or graft function at 3 years in patients with high-level viruria compared to non-JCPyV viruric patients transplanted during the same time period, and outcome was similar in patients with presumably primary and reactivated JCPyV. The mean estimated GFR at last follow-up was 44 ml/min (range 12-60 ml/min). One graft with high-level viruria was lost 9 years posttransplant due to recurrent IgA nephropathy Conclusions: High-level JCPyV viruria seems to be associated with primary JCPyV infection reflecting the average seroprevalence of 60%, but is not stringently associated with inferior graft function or survival, or histopathological changes. c 2016 Elsevier B.V. All rights reserved.Peer reviewe

Impact of human herpes virus 6 in liver transplantation

Human herpes virus 6 (HHV-6) infects > 95% of humans. Primary infection which occurs mostly during the first 2 years of life in the form of roseola infantum, non-specific febrile illness, or an asymptomatic illness, results in latency. Reactivation of latent HHV-6 is common after liver transplantation. Since the majority of human beings harbor the latent virus, HHV-6 infections after liver transplantation are most probably caused by endogenous reactivation or superinfection. In a minority of cases, primary HHV-6 infection may occur when an HHV-6-seronegative individual receives a liver allograft from an HHV-6-seropositive donor. The vast majority of HHV-6 infections after liver transplantation are asymptomatic. Only in a minority of cases, when HHV-6 causes a febrile illness associated with rash and myelosuppression, hepatitis, gastroenteritis, pneumonitis, and encephalitis after liver transplantation. In addition, HHV-6 has been implicated in a variety of indirect effects, such as allograft rejection and increased predisposition to and severity of other infections, including cytomegalovirus, hepatitis C virus, and opportunistic fungi. Because of the uncommon nature of the clinical illnesses directly attributed to HHV-6, there is currently no recommended HHV-6-specific approach prevention after liver transplantation. Asymptomatic HHV-6 infection does not require antiviral treatment, while treatment of established HHV-6 disease is treated with intravenous ganciclovir, foscarnet, or cidofovir and this should be complemented by a reduction in immunosuppression

The burden of cytomegalovirus infection remains high in high-risk kidney transplant recipients despite six-month valganciclovir prophylaxis

Cytomegalovirus continues to be a concern after transplantation despite prophylaxis regimens. Our aim was to analyse post-prophylaxis primary cytomegalovirus infections among kidney transplant recipients after 6-month valganciclovir prophylaxis and to determine the usefulness of surveillance after prophylaxis. Data from all cytomegalovirus D+/R- kidney transplant recipients from January 2004 to October 2018 at our center who received 6-month prophylaxis with valganciclovir were retrospectively analysed (N = 481). Detailed analyses were performed for 136 patients who were monitored every 2-4 weeks for DNAemia after the discontinuation of prophylaxis. Post-prophylaxis primary cytomegalovirus infection occurred in 182/481 (38%) patients median 264 days after transplantation (IQR: 226-367) and median 84 days after the end of prophylaxis (IQR: 46-187). In 49% patients, cytomegalovirus infection occurred over 3 months after the end of prophylaxis. Cytomegalovirus infection was not associated with lower patient or graft survival and no independent risk factors for infection were found. From patients monitored closely, 71/136 (52%) patients developed post-prophylaxis primary cytomegalovirus infection. Altogether, 52/136 (38%) patients were diagnosed with probable post-prophylaxis cytomegalovirus disease and 19/136 (14%) patients had asymptomatic CMV infection. Recurrent infection occurred in 38/71 (39%) patients. The incidence of post-prophylaxis primary cytomegalovirus infection among D+/R- kidney transplant recipients remains high despite 6-month prophylaxis. Surveillance after prophylaxis was challenging as a considerable portion of the infections occurred late and already symptomatic.Peer reviewe