Development and utilization of a quantitative polymerase chain reaction assay to evaluate human polyomavirus JC DNA load

AIM: Quantitative polymerase chain reaction (PCR) analysis to evaluate virus load in comparison with the patient's base-line virus levels would be an optimal diagnostic approach to monitoring human polyomavirus infections and to investigate their possible involvement in the onset of nephropathy in this patient group. Studies on the correlation between viral burden and renal disease have pointed to the incidence of JC virus (JCV) related progressive multifocal leukoencephalopathy (PML) occurring in renal and haematopoietic stem cell transplant recipients. METHODS: We developed a reliable internally-controlled quantitative PCR assay to measure JCV-DNA in fluid samples of urine, serum and cerebrospinal fluid (CSF) by densitometric analysis of the amplification products. The assay was also used to evaluate the JCV load in CFS samples from patients with suspected demyelinating syndrome and in urine and serum samples from healthy subjects and renal transplant recipients. RESULTS: All CSF samples from the 51 patients with suspected demyelinating syndrome tested JCV-DNA negative: none of them had a diagnosed PML. Analysis of the prevalence of JCV-viruria and JCV-viraemia confirmed our previous data. JCV-viruria was detected in 17% of renal transplant recipients and 26.6% of healthy controls; JCV-viraemia was found in 3.4% of transplant patients and 0% in controls. Noteworthy was a lower prevalence of JCV-viraemia in the 116 (3.4%) renal transplant patients than the prevalence previously reported for the 51 (11.8%) patients with suspected demyelinating syndrome. The mean viral load of viruria was much higher in the healthy controls than in the transplant recipients [104020 DNA copies/mL (DS+/-62284) vs 4136 DNA copies/mL (DS+/-77371)]. CONCLUSIONS: The quantitative PCR assay developed in our lab offers in 2 h time a reliable true quantification of viral DNA by densitometric analysis of the amplification product. To check for the possible presence of potential Taq polymerase inhibitors an internal control (the homemade pJCV-C plasmid) is used. The relation between polyomavirus infections and their possible involvement in post-transplant pathologies need further investigation. It would be useful to monitor the JCV-DNA load in urine and serum from more renal transplant recipients, including patients with nephropathy or active graft rejection over a longer period of time.     

异基因造血干细胞移植后巨细胞病毒及多瘤病毒感染相关临床特征

目的探讨异基因造血干细胞移植(allo-HSCT)术后人巨细胞病毒(HCMV)和多瘤病毒(BKV和JCV)感染相关临床特征。方法收集2016年6月—2017年12月共53例行allo-HSCT的恶性血液病患者临床资料。移植当天开始监测患者外周血与尿的HCMV、BKV和JCV核酸载量,每周一次至100 d。分析病毒感染的发生率、发生时间、相关临床表现及危险因素。结果 51例患者发生病毒感染,感染率为96.23%。其中,HCMV感染率为54.72%(29/53)、BKV感染率为77.36%(41/53)、JCV感染率为28.30%(15/53)。肺部感染、急性移植物抗宿主病(aGVHD)和出血性膀胱炎(HC)的发生率分别为54.72%、58.49%和20.75%。危险因素分析显示:发生aGVHD(OR=24.61,95%CI:2.30～46.24)、预处理采用全身照射(OR=33.39,95%CI:1.57～79.13)及使用ATG(OR=24.77,95%CI:1.16～52.58)是影响HCMV血症的独立危险因素,HLA全相合(OR=0.003,95%CI:0.00～0.10)可降低发生HCMV血症的风险;预处理采用全身照射(OR=15.10,95%CI:1.14～39.27)是影响BKV尿症的独立危险因素,供受者血型相合(OR=0.07,95%CI:0.01～0.64)可降低发生BKV尿症的风险。结论移植术后应尽早监测受者血及尿中HCMV及多瘤病毒感染情况,以期及时预防及减少并发症的发生。     

BK virus.

BK virus is a human polyoma virus that infects the renal epithelium and remains latent until immunosuppression triggers reactivation. After reactivation, BK virus can be detected in the urine by methods currently available in the clinical laboratory. Correlations can be made between BK viruria and the occurrence of both renal and hepatic pathologies. BK virus is emerging as a significant pathogen in transplant patients. Additionally, the presence of BK virus DNA in primary brain and pancreatic tumors suggests that it may have oncogenic potential. Thus far, attempts to treat BK virus infection have been ineffective, though research has opened new avenues for treatment possibilities. Prevention of BK virus and other latent viral reactivation remains a challenge to viral research.     

健康成人外周血白细胞中BK病毒-DNA的研究

目的检测健康成人外周血白细胞(PBLs)中BK病毒(BKV)的感染率,探讨BKV的医院感染. 方法根据BKV保守的大T抗原(TAg)编码区序列合成引物,半套式PCR(snPCR)扩增100例健康成人PBLs样本中的BKV-DNA,统计分析不同年龄、性别组BKV-DNA的检出率及其差别. 结果 100例健康成人PBLs样本中BKV-DNA序列检出率为45%,不同年龄、性别组之间差异无显著性(P>0.05). 结论健康人PBLs是BKV在体内潜伏的重要贮主和传播运载体,BKV是重要的医院感染病原体之一.     

移植患者免疫抑制剂治疗后感染多瘤病毒及巨细胞病毒的现状

目的 探讨移植患者在接受免疫抑制剂他克莫司(FK506)治疗后感染多瘤病毒(BKV)与巨细胞病毒(CMV)情况,为器官移植研究提供流行病学依据.方法 采用FQ-PCR检测605例肝、肾、骨髓移植患者BKV和CMV的感染载量,ELISA检测患者FK506的血药浓度,并对结果进行统计分析.结果 605份标本中,共检测BKV感染者79例,感染率为13.06％,CMV感染148例,感染率为24.46％,双重病毒感染者为35例,感染率为5.79％;肝移植患者感染BKV和CMV阳性率为12.61％和15.97％,肾移植则分别为13.33％和27.08％,而6例骨髓移植标本则未发现病毒感染;CMV感染阳性率明显高于BKV,而病毒感染阳性者,则其FK506血药浓度较高(P＜0.05).结论 移植患者在使用免疫抑制剂FK506后易感染BKV和CMV,并且感染程度与FK506血药浓度相关.     

北京市孕妇BK病毒感染情况的调查

对北京市467名孕妇进行人类多瘤病毒BK的抗体测定,其中包括妊娠28周前孕妇329名和妊娠足月孕妇138名,孕妇血清IgG抗体阳性率为77.94%,与未孕健康妇女的抗体阳性率无显著差别。孕妇IgM抗体阳性率为7.49%,未孕妇女未测出IgM。检测75名孕妇双份血清,抗体效价呈4倍以上增长的15例。以上说明,妊娠期中有BKV的近期激活。     

Biology,evolution, and medical importance of polyomaviruses: An update

The family Polyomaviridae encompasses non-enveloped viruses with a circular dsDNA genome that is typically approximately 5000 bp in length. Originally isolated from mammals, polyomavirus sequences have now been detected in invertebrates, fish, amphibians, reptiles and birds, although it remains to be determined whether all these animals are genuine hosts. The genomes of all polyomaviruses encode at least two regulatory proteins (large and small tumour antigen) and two structural proteins (capsid proteins VP1 and VP2) whose functions have been defined. The large and small tumour antigens have domains conserved among the polyomaviruses, which are responsible for specific interactions with cellular proteins and may result in alteration of the cell cycle. Additional open reading frames (ORFs) are present in the genomes of the different polyomavirus species. Some of these ORFs are transcribed and translated in viral proteins, but their functions remain poorly understood. Polyomaviruses have a restricted host specificity. This may indicate that co-divergence with their hosts, which has been demonstrated in a few cases, was an important factor during polyomavirus diversification. However, a strict co-divergence scenario fails to explain family-wide patterns of diversity, suggesting an important contribution of lineage duplication and, possibly to a lesser extent, recombination and cross-species transmission. Polyomaviruses are pathogens that can cause various malignant and non-malignant diseases in birds and mammals, including humans, but so far they have not been linked to disease in lower vertebrates. In immunosuppressed individuals, reactivation of polyomavirus BK or JC can cause serious disease of the urogenital tract and brain, respectively, while Merkel cell polyomavirus is most probably associated with the development of a highly aggressive neuroendocrine skin tumour in elderly or patients with pre-existing conditions. This review provides an update on the life cycle, prevalence, disease association, and evolution of the viruses belonging to this family.     

Population genetic tests suggest that the epidemiologies of JCV and BKV are strikingly different

The JCV and BKV viruses have been used as markers for the study of human evolution by assuming that these viruses coevolved with their host. However, it is currently unclear whether the details of the population expansion of these viruses and humans agree. To study this in more detail, large numbers of complete genomes were used for population genetic tests to detect evidence for population expansion. Relative to the neutral expectation of no selective forces and no demographic changes, the JCV data set contained a striking excess of synonymous and non-synonymous mutations that occur only once in the data set. The same was found for non-synonymous mutations of BKV, but not at all for synonymous mutations of BKV. The different frequency spectra of mutations in JCV and BKV do not result from the inclusion of patients with clinical symptoms associated with BKV and JCV, such as nephropathy or progressive multifocal leucoencefalopathy, nor from the different numbers of genomes available for JCV and BKV. Instead, the distribution of unique mutations and population genetic models that use older mutation classes indicate a striking difference of the historical demographies of JCV and BKV with only the former virus exhibiting the evidence of demographic expansion. Our analyses expand on recent population genetic analyses that document a global population expansion of JCV by taking into account the impact of deleterious mutations and by comparing both human viruses. The striking difference between the demographics of BKV and JCV suggests that important aspects of their epidemiology remain to be discovered.     

Human Polyomavirus 9 Infection in Kidney Transplant Patients

Several human polyomaviruses of unknown prevalence and pathogenicity have been identified, including human polyomavirus 9 (HPyV9). To determine rates of HPyV9 infection among immunosuppressed patients, we screened serum samples from 101 kidney transplant patients in the Netherlands for HPyV9 DNA and seroreactivity. A total of 21 patients had positive results for HPyV9 DNA; positivity rates peaked at 3 months after transplantation, but the highest viral loads were measured just after transplantation. During 18 months of follow-up, HPyV9 seroprevalence increased from 33% to 46% among transplant patients; seroprevalence remained stable at ≈30% in a control group of healthy blood donors in whom no HPyV9 DNA was detected. Further analysis revealed an association between detection of HPyV9 and detection of BK polyomavirus but not of cytomegalovirus. Our data indicate that HPyV9 infection is frequent in kidney transplant patients, but the nature of infection—endogenous or donor-derived—and pathogenic potential of this virus remain unknown.     

An immunoinformatic approach to universal therapeutic vaccine design against BK virus

In kidney transplant recipients (KTRs) long-term immunosuppression leads to BK virus (BKV) reactivation, with an increased incidence of BKV-associated pathologies and allograft rejection. The current approaches to limit BKV infection include a reduction in immunosuppression and use of anti-BKV drugs, which are clinically sub-optimal and lead to undesirable therapeutic outcomes. Here, we adopted an immune-based approach to augment the endogenous BKV specific T-cells. Using reverse vaccinology based in silico analyses, we designed a peptide-based multi-epitope vaccine for BKV (MVBKV). A major advantage of our approach is that the selected epitopes show an affinity towards all the 12 superfamilies of HLA class I alleles and 27 reference alleles of HLA class II. This suggests MVBKV’s universal nature and its potential effectiveness in a wide-population base. To improve MVBKV’s immunogenic properties, a synthetic Toll-like Receptor (TLR) 4 peptide ligand (RS09) was added to the final vaccine construct. The sequences of the individual epitopes were molecularly linked to form a 3D-stable synthetic protein. Overall, our immunoinformatic-based approach led to the design of a new MVBKV vaccine, which remains to be validated experimentally.     

广西瑶、侗、苗、壮等民族外周血白细胞中BK病毒的研究

目的了解广西瑶、侗、苗、壮等少数民族外周血白细胞中多瘤病毒BKV的感染情况，掌握该区人群BKV的携带情况，阐明BKV在人体内的传播方式。方法于2006年1月-2008年5月采集广西瑶、侗、苗、壮等少数民族及汉族健康人外周血标本各2500份，提取淋巴细胞基因组DNA，用巢式PCR方法扩增BKV的保守区编码序列，统计分析不同少数民族、年龄、性别组BKV—DNA检出率。结果2500份健康人外周血白细胞（PBLs）样品中BKV—DNA序列检出率为60．6％，不同民族、性别、年龄组之间无显著性差异（P〉0．05）。结论BKV在广西瑶、侗、苗、壮等少数民族及汉族健康人PBLs中存在较高的感染率，本研究证实了PBLs是BKV在体内的潜伏细胞及传播载体，应加强对BKV条件致病性的认识，积极防治、减少BKV相关性肾病（BKVN）的发生率。     

Seroprevalence of trichodysplasia spinulosa-associated polyomavirus

We identified a new polyomavirus in skin lesions from a patient with trichodysplasia spinulosa (TS). Apart from TS being an extremely rare disease, little is known of its epidemiology. On the basis of knowledge regarding other polyomaviruses, we anticipated that infections with trichodysplasia spinulosa-associated polyomavirus (TSV) occur frequently and become symptomatic only in immunocompromised patients. To investigate this hypothesis, we developed and used a Luminex-based TSV viral protein 1 immunoassay, excluded cross-reactivity with phylogenetically related Merkel cell polyomavirus, and measured TSV seroreactivity. Highest reactivity was found in a TS patient. In 528 healthy persons in the Netherlands, a wide range of seroreactivities was measured and resulted in an overall TSV seroprevalence of 70% (range 10% in small children to 80% in adults). In 80 renal transplant patients, seroprevalence was 89%. Infection with the new TSV polyomavirus is common and occurs primarily at a young age.     

Comparison of the immunogenicity of Dukoral® oral cholera vaccine between renal transplant recipients on either a calcineurin inhibitor or mycophenolate – A controlled trial

BackgroundThe evidence for recommendations regarding vaccination in solid organ transplant recipients is sparse. There is little data comparing vaccine responses between groups on different immunosuppressive drugs. This study was conducted to evaluate the antibody response to Dukoral® oral cholera vaccine in renal transplant recipients (RTR).MethodsIn a single-center non-randomized controlled clinical trial, healthy volunteers (n = 21) and renal transplant recipients (n = 30) were vaccinated with the oral whole cell/recombinant B subunit cholera vaccine Dukoral® (Valneva Inc., Vienna, Austria). The RTR were stratified according to their maintenance immunosuppressive therapy: either prednisone and a calcineurin inhibitor (cyclosporine A or tacrolimus; P/CNI group; n = 15) or prednisone and mycophenolate (P/MMF group; n = 15). All volunteers ingested Dukoral® at baseline and at day 14. Serum samples were drawn at day 0 and day 21. The primary outcome was seroconversion, defined as either a 3-fold IgA serum titer increase in anti-cholera toxin B antibodies and/or a 4-fold rise in the serum vibriocidal titer.ResultsFollow-up was complete. Seroconversion after vaccination was 57% (standard error, SE 9%) in RTR and 81% (SE 9%) in healthy controls (Relative Risk, RR 0.70; 95% CI 0.48–1.02). When stratified according to maintenance immunosuppression, the seroconversion rate was 67% (SE 12%) in the P/CNI group (RR compared with controls 0.82; 95% CI 0.55–1.25) and 47% (SE 13%) in the P/MMF group (RR compared with controls 0.58; 95% CI 0.32–1.03).ConclusionAdverse events were mild to moderate and transient. The response to Dukoral was weaker and the seroconversion rate was lower in renal transplant recipients than in healthy controls. In particular, those using mycophenolate had a poor response. Nevertheless, more than half of the transplant recipients seroconverted. Therefore oral vaccines should not be discarded as a potential tool for protection of solid organ transplant recipients.This trial is registered in clinicaltrials.gov under NCT01109914.     

Hepatic de novo lipogenesis after liver transplantation

BACKGROUND: The liver can synthesize fatty acids from carbohydrate (de novo lipogenesis [DNL]). We hypothesized that stimulation of this process may be involved in the development of obesity and dyslipidemia, 2 conditions frequently encountered after liver transplantation. METHODS: Hepatic fractional DNL and glucose metabolism were measured in 2 groups of 5 patients (age 36.8 +/- [SD] 14.9 years, BMI 26.3+/-5.3 kg/M2) 1 to 5 years after liver transplantation and 8 healthy subjects (age 28.1+/-5.3 years, BMI 27.2+/-4.5 kg/M2). Subjects were studied while receiving an isoenergetic nutrition (based on 1.1 x their basal energy expenditure) as hourly oral liquid formula during 10 hours. Their hepatic DNL was measured by infusing 1-13C acetate and measuring tracer incorporation in VLDL-palmitate. Their glucose metabolism was assessed by means of 6,6-2H2 glucose and indirect calorimetry. RESULTS: Two liver transplant recipients and 4 healthy subjects were obese, as defined by a BMI > 27 kg/M2. Fractional hepatic DNL was not different in the 2 groups of subjects: liver transplant recipients 3.1+/-1.7% vs 3.2+/-2.1% in healthy subjects. In both groups, DNL increased in proportion to BMI. When both groups were analyzed together, BMI was positively correlated with DNL (DNL = 0.28 x BMI - 4.28, r2 = .445, p < .05). Whole body glucose turnover was 15.0+/-4.4 micromol/kg per minute in liver transplant recipients and 15.8+/-4.1 micromol/kg per minute in healthy subjects (NS). Net carbohydrate oxidation tended to be lower in liver transplant recipients (8.1+/-2.6 micromol/kg per minute) than in healthy subjects (10.4+/-2.4 micromol/kg per minute; NS). Net nonoxidative glucose disposal (4.0+/-2.7 in liver transplant recipients vs 1.9+/-1.8 in healthy subjects, NS) and energy expenditure (0.065+/-0.01 vs 0.065+/-0.01 kJ/kg per minute) were similar in both groups. CONCLUSIONS: These results indicate that fractional hepatic DNL is not altered by liver transplantation during near continuous nutrition. The disposal of orally administered carbohydrate is also essentially unchanged. This strongly argues against a role of hepatic DNL in the pathogenesis of obesity and dyslipidemia after liver transplantation.     

The Impact of Kidney Transplantation on the Serum Fatty Acid Profile in Patients with End-Stage Kidney Disease

Epidemiological data indicate that metabolic disturbances and increased cardiovascular risk in renal transplant patients are a significant and common problem. Therefore, it is important to search for new solutions and, at the same time, counteract the negative effects of currently used therapies. In this study, we examined the effect of kidney transplantation on the serum levels of fatty acids (FAs) in order to assess the role of these compounds in the health of transplant patients. The FA profile was analyzed by gas chromatography-mass spectrometry in the serum of 35 kidney transplant recipients, just before transplantation and 3 months later. The content of total n-3 polyunsaturated FAs (PUFAs) decreased after transplantation (3.06 ± 0.13% vs. 2.66 ± 0.14%; p < 0.05). The total amount of ultra-long-chain FAs containing 26 and more carbon atoms was significantly reduced (0.08 ± 0.009% vs. 0.05 ± 0.007%; p < 0.05). The desaturation index (18:1/18:0) increased after transplantation (3.92 ± 0.11% vs. 4.36 ± 0.18%; p < 0.05). The study showed a significant reduction in n-3 PUFAs in renal transplant recipients 3 months after transplantation, which may contribute to increased cardiovascular risk in this patient population.     

Hospitalized congestive heart failure after renal transplantation in the United States

PURPOSE: African Americans have increased risk for congestive heart failure (CHF) compared to Caucasians in the general population, but the risk of CHF in African American renal transplant recipients has not been studied in a national renal transplant population. METHODS: Therefore, 33,479 renal transplant recipients in the United States Renal Data System (USRDS) from 1 July, 1994 to 30 June, 1997 were analyzed in an historical cohort study of the incidence, associated factors, and mortality of hospitalizations with a primary discharge diagnosis of CHF [International Classification of Diseases-9 (ICD9) Code 428.x]. RESULTS: African American renal transplant recipients had increased age-adjusted risk of hospitalizations for congestive heart failure compared to African Americans in the general population [rate ratio 4.60, 95% confidence interval (CI) 4.59-4.62]. In logistic regression analysis, African American recipients had increased risk of congestive heart failure after renal transplantation, independent of other factors. Among other significant factors associated with congestive heart failure, the strongest were graft loss and allograft rejection. No maintenance immunosuppressive medications were associated with CHF. In Cox regression analysis patients hospitalized for CHF had increased all-cause mortality compared with all other recipients (hazard ratio 3.69, 95% CI, 2.23-6.10), but African American recipients with CHF were not at significantly increased risk of mortality compared to Caucasian recipients with CHF. CONCLUSIONS: African Americans recipients were at high risk for CHF after transplant independent of other factors. The reasons for this increased risk should be the subject of further study. All potential transplant recipients should receive particular attention for the diagnosis and prevention of CHF in the transplant evaluation process, which includes preservation of allograft function.     

BK-virus infections: a literature review

BK-virus is a very common polyomavirus in the global population, similar to the JC-virus responsible for Progressive Multifocal Leukoencephalopathy. BK-virus infections are an important diagnostic and therapeutic challenge in immuno-compromised patients, including: bone marrow transplant pediatric recipients in whom it may cause hemorrhagic cystitis, renal transplant recipients in whom it may cause interstitial nephropathy leading to graft loss, and in HIV infected patients in whom it may cause some types of encephalitis. Indeed, this poorly documented virus is responsible for infections with various clinical profiles, probably under-diagnosed, but could also be involved in the genesis of some cancers, especially cervix and prostate cancer. We reviewed the latest published data on this virus focusing on its possible pro-oncogenic properties. We also listed the diseases in which it is involved, with an emphasis on rare and insufficiently investigated entities. Finally, we studied the new tools available for diagnosis and treatment, and their importance in current practice.     

Evolution of four BK virus subtypes

BK viruses (BKV) comprise four subtypes that are distinguishable by serological and molecular methods with the latter indicating up to four subgroups within subtype I. In this study, the phylogeny of all BKV subtypes was analyzed. Phylogenetic analyses of the viral structural protein VP1, concatenated sequences including the T-Ag, t-Ag, VP1 and VP2 genes and the entire coding region of BKV, each employing several tree inference methods, consistently revealed seven strongly supported clades that correlate with BKV subtypes and subgroups. In general, subtype II and III viruses were found to be sister groups, the genetic distances between which were significantly lower than those between either and the other BKV subtypes. Two benchmarks of human evolution (emergence of modern humans, 200,000 years ago; out-of-Africa migration, 100,000 years ago) were assumed for the internal calibration of BKV evolution. Utilization of either calibration point resulted in the diversification of most BKV subgroups coinciding with human radiation less than 50,000 years ago. Another approach, external calibration by linking BKV divergence to the evolution of mammals, was rejected as it advances BKV divergence prior to the emergence of modern humans.     

他克莫司个体内高变异度与肾移植受者移植结局的关系探讨

目的探讨他克莫司(tacrolimus，Tac)个体内变异度(intra-patient variability，IPV)是否与肾移植受者慢性移植物失功密切相关。 方法选取2009年1月至2016年12月在四川大学华西医院肾移植中心进行肾移植且在术后长期随访的肾移植受者共1167人，用移植后7~12月期间的Tac全血浓度计算得到Tac IPV。设定的结局(含终点)包括：(1)移植物衰竭，再移植，(再)开始透析，或肾小球滤过率(glomerular filtration rate，eGFR)≤15 ml/min，活检证实的急性排斥反应(biopsy-proven acute rejection，BPAR)；(2)组织学确定的移植肾小球病；(3)移植后12个月到最后一次随访期间，血清肌酐浓度加倍；(4)最后一次随访。分析不同IPV组肾移植受者肾脏功能差异，生存时间差异以及出现慢性移植物失功的情况。 结果纳入研究的1167位患者中，有79(6.8%)位到达了移植物失功的终点。肾移植受者移植后7~12月Tac IPV平均值为25.7%；高IPV组移植后第15个月血清肌酐显著高于低IPV组(P<0.05)，第15、21、24个月eGFR显著低于低IPV组(P<0.05)。多因素Cox回归分析结果显示：Tac IPV对肾移植预后的预测有一定作用，但并不显著(P=0.051，Harzards ratio：1.015，95%CI：1.000-1.031)。而受者的年龄、性别、移植后6 h的移植物功能，是移植物存活的独立预测因子。 结论高Tac IPV与肾移植受者移植物失功有一定临床相关性，同时高Tac IPV是预测肾移植受者移植后两年内肾脏功能的重要实验室指标。