Using longitudinally sampled viral nucleotide sequences to characterize the drivers of HIV-1 transmission.

OBJECTIVES: Understanding the drivers of HIV-1 transmission is of importance for curbing the ongoing epidemic. Phylogenetic methods based on single viral sequences allow us to assess whether two individuals are part of the same viral outbreak, but cannot on their own assess who potentially transmitted the virus. We developed and assessed a molecular epidemiology method with the main aim to screen cohort studies for and to characterize individuals who are 'potential HIV-1 transmitters', in order to understand the drivers of HIV-1 transmission. METHODS: We developed and validated a molecular epidemiology approach using longitudinally sampled viral Sanger sequences to characterize potential HIV-1 transmitters in the Swiss HIV Cohort Study. RESULTS: Our method was able to identify 279 potential HIV-1 transmitters and allowed us to determine the main epidemiological and virological drivers of transmission. We found that the directionality of transmission was consistent with infection times for 72.9% of 85 potential HIV-1 transmissions with accurate infection date estimates. Being a potential HIV-1 transmitter was associated with risk factors including viral load [adjusted odds ratiomultivariable (95% confidence interval): 1.86 (1.49-2.32)], syphilis coinfection [1.52 (1.06-2.19)], and recreational drug use [1.45 (1.06-1.98)]. By contrast for the potential HIV-1 recipients, this association was weaker or even absent [1.18 (0.82-1.72), 0.89 (0.52-1.55) and 1.53 (0.98-2.39), respectively], indicating that inferred directionality of transmission is useful at the population level. CONCLUSIONS: Our results indicate that longitudinally sampled Sanger sequences do not provide sufficient information to identify transmitters with high certainty at the individual level, but that they allow the drivers of transmission at the population level to be characterized.

Clostridium difficile infection is associated with graft loss in solid organ transplant recipients.

Clostridium difficile infection (CDI) is a leading cause of infectious diarrhea in solid organ transplant recipients (SOT). We aimed to assess incidence, risk factors, and outcome of CDI within the Swiss Transplant Cohort Study (STCS). We performed a case-control study of SOT recipients in the STCS diagnosed with CDI between May 2008 and August 2013. We matched 2 control subjects per case by age at transplantation, sex, and transplanted organ. A multivariable analysis was performed using conditional logistic regression to identify risk factors and evaluate outcome of CDI. Two thousand one hundred fifty-eight SOT recipients, comprising 87 cases of CDI and 174 matched controls were included. The overall CDI rate per 10 000 patient days was 0.47 (95% confidence interval ([CI] 0.38-0.58), with the highest rate in lung (1.48, 95% CI 0.93-2.24). In multivariable analysis, proven infections (hazard ratio [HR] 2.82, 95% CI 1.29-6.19) and antibiotic treatments (HR 4.51, 95% CI 2.03-10.0) during the preceding 3 months were independently associated with the development of CDI. Despite mild clinical presentations, recipients acquiring CDI posttransplantation had an increased risk of graft loss (HR 2.24, 95% CI 1.15-4.37; P = .02). These findings may help to improve the management of SOT recipients.

BK Polyomavirus-Specific 9mer CD8 T Cell Responses Correlate With Clearance of BK Viremia in Kidney Transplant Recipients: First Report From the Swiss Transplant Cohort Study.

BK polyomavirus (BKPyV) causes premature kidney transplant (KT) failure in 1-15% of patients. Because antivirals are lacking, most programs screen for BKPyV-viremia and, if positive, reduce immunosuppression. To evaluate the relationship of viremia and BKPyV-specific immunity, we examined prospectively cryopreserved plasma and peripheral blood mononuclear cells at the time of transplantation (T0) and at 6 mo (T6) and 12 mo (T12) after transplant from 28 viremic KT patients and 68 nonviremic controls matched for the transplantation period. BKPyV IgG seroprevalence was comparable between cases (89.3%) and controls (91.2%; p = 0.8635), but cases had lower antibody levels (p = 0.022) at T0. Antibody levels increased at T6 and T12 but were not correlated with viremia clearance. BKPyV-specific T cell responses to pools of overlapping 15mers (15mer peptide pool [15mP]) or immunodominant CD8 9mers (9mer peptide pool [9mP]) from the early viral gene region were not different between cases and controls at T0; however, clearance of viremia was associated with stronger 9mP responses at T6 (p = 0.042) and T12 (p = 0.048), whereas 15mP responses were not informative (T6 p = 0.359; T12 p = 0.856). BKPyV-specific T cells could be expanded in vitro from all patients after transplant, permitting identification of 78 immunodominant 9mer epitopes including 50 new ones across different HLA class I. Thus, 9mP-responses may be a novel marker of reconstituting CD8 T cell function that warrants further study as a complement of plasma BKPyV loads for guiding immunosuppression reduction.

Preventive Strategies Against Cytomegalovirus and Incidence of α-Herpesvirus Infections in Solid Organ Transplant Recipients: A Nationwide Cohort Study.

We assessed the impact of antiviral preventive strategies on the incidence of herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections in a nationwide cohort of transplant recipients. Risk factors for the development of HSV or VZV infection were assessed by Cox proportional hazards regression. We included 2781 patients (56% kidney, 20% liver, 10% lung, 7.3% heart, 6.7% others). Overall, 1264 (45%) patients received antiviral prophylaxis (ganciclovir or valganciclovir, n = 1145; acyclovir or valacyclovir, n = 138). Incidence of HSV and VZV infections was 28.9 and 12.1 cases, respectively, per 1000 person-years. Incidence of HSV and VZV infections at 1 year after transplant was 4.6% (95% confidence interval [CI] 3.5-5.8) in patients receiving antiviral prophylaxis versus 12.3% (95% CI 10.7-14) in patients without prophylaxis; this was observed particularly for HSV infections (3% [95% CI 2.2-4] versus 9.8% [95% CI 8.4-11.4], respectively). A lower rate of HSV and VZV infections was also seen in donor or recipient cytomegalovirus-positive patients receiving ganciclovir or valganciclovir prophylaxis compared with a preemptive approach. Female sex (hazard ratio [HR] 1.663, p = 0.001), HSV seropositivity (HR 5.198, p < 0.001), previous episodes of rejection (HR 1.95, p = 0.004), and use of a preemptive approach (HR 2.841, p = 0.017) were significantly associated with a higher risk of HSV infection. Although HSV and VZV infections were common after transplantation, antiviral prophylaxis significantly reduced symptomatic HSV infections.

Epidemiology and Immediate Indirect Effects of Respiratory Viruses in Lung Transplant Recipients: A 5-Year Prospective Study.

The epidemiology of respiratory viruses (RVs) in lung transplant recipients (LTRs) and the relationship of RVs to lung function, acute rejection (AR) and opportunistic infections in these patients are not well known. We performed a prospective cohort study (2009-2014) by collecting nasopharyngeal swabs (NPSs) from asymptomatic LTRs during seasonal changes and from LTRs with upper respiratory tract infectious disease (URTID), lower respiratory tract infectious disease (LRTID) and AR. NPSs were analyzed by multiplex polymerase chain reaction. Overall, 1094 NPSs were collected from 98 patients with a 23.6% positivity rate and mean follow-up of 3.4 years (interquartile range 2.5-4.0 years). Approximately half of URTIDs (47 of 97, 48.5%) and tracheobronchitis cases (22 of 56, 39.3%) were caused by picornavirus, whereas pneumonia was caused mainly by paramyxovirus (four of nine, 44.4%) and influenza (two of nine, 22.2%). In LTRs with LRTID, lung function changed significantly at 1 mo (p = 0.03) and 3 mo (p = 0.04). In a nested case-control analysis, AR was associated with RVs (hazard ratio [HR] 6.54), Pseudomonas aeruginosa was associated with LRTID (HR 8.54), and cytomegalovirus (CMV) replication or disease was associated with URTID (HR 2.53) in the previous 3 mo. There was no association between RVs and Aspergillus spp. colonization or infection (HR 0.71). In conclusion, we documented a high incidence of RV infections in LTRs. LRTID produced significant lung function abnormalities. Associations were observed between AR and RVs, between P. aeruginosa colonization or infection and LRTID, and between CMV replication or disease and URTID.

Emergence of Acquired HIV-1 Drug Resistance Almost Stopped in Switzerland: A 15-Year Prospective Cohort Analysis.

BACKGROUND: Drug resistance is a major barrier to successful antiretroviral treatment (ART). Therefore, it is important to monitor time trends at a population level. METHODS: We included 11 084 ART-experienced patients from the Swiss HIV Cohort Study (SHCS) between 1999 and 2013. The SHCS is highly representative and includes 72% of patients receiving ART in Switzerland. Drug resistance was defined as the presence of ≥1 major mutation in a genotypic resistance test. To estimate the prevalence of drug resistance, data for patients with no resistance test was imputed based on the patient's risk of harboring drug-resistant viruses. RESULTS: The emergence of new drug resistance mutations declined dramatically from 401 to 23 patients between 1999 and 2013. The upper estimated prevalence limit of drug resistance among ART-experienced patients decreased from 57.0% in 1999 to 37.1% in 2013. The prevalence of 3-class resistance decreased from 9.0% to 4.4% and was always <0.4% for patients who initiated ART after 2006. Most patients actively participating in the SHCS in 2013 with drug-resistant viruses initiated ART before 1999 (59.8%). Nevertheless, in 2013, 94.5% of patients who initiated ART before 1999 had good remaining treatment options based on Stanford algorithm. CONCLUSIONS: Human immunodeficiency virus type 1 drug resistance among ART-experienced patients in Switzerland is a well-controlled relic from the era before combination ART. Emergence of drug resistance can be virtually stopped with new potent therapies and close monitoring.

BK Polyomavirus Infection and Renourinary Tumorigenesis.

BK polyomavirus (BKPyV) infection represents a major problem in transplantation, particularly for renal recipients developing polyomavirus-associated nephropathy (PyVAN). The possibility that BKPyV may also be oncogenic is not routinely considered. Twenty high-grade renourinary tumors expressing polyomavirus large T antigen in the entirety of the neoplasm in 19 cases, including the metastases in six, have been reported in transplant recipients with a history of PyVAN or evidence of BKPyV infection. Morphological and phenotypical features consistent with inactivation of the tumor suppressors pRB and p53 were found in the bladder tumors, suggesting a carcinogenesis mechanism involving the BKPyV large tumor oncoprotein/antigen. The pathogenesis of these tumors is unclear, but given the generally long interval between transplantation and tumor development, the risk for neoplasms after BKPyV infections may well be multifactorial. Other elements potentially implicated include exposure to additional exogenous carcinogens, further viral mutations, and cell genomic instability secondary to viral integration, as occurs with the Merkel cell PyV-associated carcinoma. The still scarce but increasingly reported association between longstanding PyVAN and renourinary neoplasms requires a concerted effort from the transplant community to better understand, diagnose, and treat the putative association between the BKPyV and these neoplasms.

HIV-1 Transmission During Recent Infection and During Treatment Interruptions as Major Drivers of New Infections in the Swiss HIV Cohort Study.

BACKGROUND: Reducing the fraction of transmissions during recent human immunodeficiency virus (HIV) infection is essential for the population-level success of "treatment as prevention". METHODS: A phylogenetic tree was constructed with 19 604 Swiss sequences and 90 994 non-Swiss background sequences. Swiss transmission pairs were identified using 104 combinations of genetic distance (1%-2.5%) and bootstrap (50%-100%) thresholds, to examine the effect of those criteria. Monophyletic pairs were classified as recent or chronic transmission based on the time interval between estimated seroconversion dates. Logistic regression with adjustment for clinical and demographic characteristics was used to identify risk factors associated with transmission during recent or chronic infection. FINDINGS: Seroconversion dates were estimated for 4079 patients on the phylogeny, and comprised between 71 (distance, 1%; bootstrap, 100%) to 378 transmission pairs (distance, 2.5%; bootstrap, 50%). We found that 43.7% (range, 41%-56%) of the transmissions occurred during the first year of infection. Stricter phylogenetic definition of transmission pairs was associated with higher recent-phase transmission fraction. Chronic-phase viral load area under the curve (adjusted odds ratio, 3; 95% confidence interval, 1.64-5.48) and time to antiretroviral therapy (ART) start (adjusted odds ratio 1.4/y; 1.11-1.77) were associated with chronic-phase transmission as opposed to recent transmission. Importantly, at least 14% of the chronic-phase transmission events occurred after the transmitter had interrupted ART. CONCLUSIONS: We demonstrate a high fraction of transmission during recent HIV infection but also chronic transmissions after interruption of ART in Switzerland. Both represent key issues for treatment as prevention and underline the importance of early diagnosis and of early and continuous treatment.

BK Polyomavirus Replication in Renal Tubular Epithelial Cells Is Inhibited by Sirolimus, but Activated by Tacrolimus Through a Pathway Involving FKBP-12.

BK polyomavirus (BKPyV) replication causes nephropathy and premature kidney transplant failure. Insufficient BKPyV-specific T cell control is regarded as a key mechanism, but direct effects of immunosuppressive drugs on BKPyV replication might play an additional role. We compared the effects of mammalian target of rapamycin (mTOR)- and calcineurin-inhibitors on BKPyV replication in primary human renal tubular epithelial cells. Sirolimus impaired BKPyV replication with a 90% inhibitory concentration of 4 ng/mL by interfering with mTOR-SP6-kinase activation. Sirolimus inhibition was rapid and effective up to 24 h postinfection during viral early gene expression, but not thereafter, during viral late gene expression. The mTORC-1 kinase inhibitor torin-1 showed a similar inhibition profile, supporting the notion that early steps of BKPyV replication depend on mTOR activity. Cyclosporine A also inhibited BKPyV replication, while tacrolimus activated BKPyV replication and reversed sirolimus inhibition. FK binding protein 12kda (FKBP-12) siRNA knockdown abrogated sirolimus inhibition and increased BKPyV replication similar to adding tacrolimus. Thus, sirolimus and tacrolimus exert opposite effects on BKPyV replication in renal tubular epithelial cells by a mechanism involving FKBP-12 as common target. Immunosuppressive drugs may therefore contribute directly to the risk of BKPyV replication and nephropathy besides suppressing T cell functions. The data provide rationales for clinical trials aiming at reducing the risk of BKPyV replication and disease in kidney transplantation.

Characterization of Immunodominant BK Polyomavirus 9mer Epitope T Cell Responses.

Uncontrolled BK polyomavirus (BKPyV) replication in kidney transplant recipients (KTRs) causes polyomavirus-associated nephropathy and allograft loss. Reducing immunosuppression is associated with clearing viremia and nephropathy and increasing BKPyV-specific T cell responses in most patients; however, current immunoassays have limited sensitivity, target mostly CD4(+) T cells, and largely fail to predict onset and clearance of BKPyV replication. To characterize BKPyV-specific CD8(+) T cells, bioinformatics were used to predict 9mer epitopes in the early viral gene region (EVGR) presented by 14 common HLAs in Europe and North America. Thirty-nine EVGR epitopes were experimentally confirmed by interferon-γ enzyme-linked immunospot assays in at least 30% of BKPyV IgG-seropositive healthy participants. Most 9mers clustered in domains, and some were presented by more than one HLA class I, as typically seen for immunodominant epitopes. Specific T cell binding using MHC class I streptamers was demonstrated for 21 of 39 (54%) epitopes. In a prospective cohort of 118 pediatric KTRs, 19 patients protected or recovering from BKPyV viremia were experimentally tested, and 13 epitopes were validated. Single HLA mismatches were not associated with viremia, suggesting that failing immune control likely involves multiple factors including maintenance immunosuppression. Combining BKPyV load and T cell assays using immunodominant epitopes may help in evaluating risk and reducing immunosuppression and may lead to safe adoptive T cell transfer.

Multicentric performance analysis of HCV quantification assays and its potential relevance for HCV treatment.

An accurate quantification of low viremic HCV RNA plasma samples has gained importance since the approval of direct acting antivirals and since only one single measurement predicts the necessity of a prolonged or shortened therapy. As reported previously, HCV quantification assays such as Abbott RealTime HCV and Roche COBAS AmpliPrep/COBAS TaqMan HCV version 2 (CTM v2) may vary in sensitivity and precision particularly in low-level viremia. Importantly, substantial variations were previously demonstrated between some of these assays compared to the Roche High Pure System/COBAS TaqMan assay (HPS) reference assay, which was used to establish the clinical decision points in clinical studies. In this study, the reproducibility of assay performances across several laboratories was assessed by analysing quantification results generated by six independent laboratories (3× RealTime, 3× CTM v2) in comparison with one HPS reference laboratory. The 4th WHO Standard was diluted to 100, 25 and 10 IU/ml, and aliquots were tested in triplicates in 5 independent runs by each assay in the different laboratories to assess assay precision and detection rates. In a second approach, 2 clinical samples (GT 1a & GT 1b) were diluted to 100 and 25 IU/ml and tested as described above. While the result range for WHO 100 IU/ml replicates across all laboratories was similar in this analysis, the CVs of each laboratory ranged from 19.3 to 25.6 % for RealTime laboratories and were lower than CVs of CTM v2 laboratories with a range of 26.1-47.3 %, respectively, and also in comparison with the CV of the HPS reference laboratory (34.9 %). At WHO standard dilution of 25 IU/ml, 24 replicates were quantified by RealTime compared to 8 replicates with CTM v2. Results of clinical samples again revealed a higher variation of CTM v2 results as compared to RealTime values. (CVs at 100 IU/ml: RealTime: 13.1-21.0 % and CTM v2: 15.0-32.3 %; CVs at 25 IU/ml: RealTime 17.6-34.9 % and CTM v2 28.2-54.9 %). These findings confirm the superior precision of RealTime versus CTM v2 at low-level viremia even across different laboratories including the new clinical decision point at 25 IU/ml. A highly precise monitoring of HCV viral load during therapy will remain crucial for patient management with regard to futility rules, therapy efficacy and SVR.

The "ABC" of Virus-Specific T Cell Immunity in Solid Organ Transplantation.

Transplant patients are at increased risk of viral complications due to impaired control of viral replication, resulting from HLA mismatching between graft and host and the immunosuppression needed to avert alloimmune reactions. In the past decade, quantitative viral load measurements have become widely available to identify patients at risk and to inform treatment decisions with respect to immunosuppressive drugs and antiviral therapies. Because viral loads are viewed as the result of viral replication and virus-specific immune control, virus-specific T cell monitoring has been explored to optimize management of adenovirus, BK polyomavirus and cytomegalovirus ("ABC") in transplant patients. Although most studies are descriptive using different technologies, the overall results show that the quantity and quality of virus-specific T cells inversely correlate with viral replication, whereby strong cellular immune responses are associated with containment of viral replication. The key obstacles to the introduction of assays for virus-specific T cells into clinical practice is the definition of reliable cutoffs for clinical decision making, the poor negative predictive value of some assays, and the absence of interventional trials justifying changes of antiviral treatment or immunosuppression. More clinical research is needed using optimized assays and targets before standardization and commutability can be envisaged as achieved for viral load testing.

Combination therapy for multidrug-resistant cytomegalovirus disease.

Multidrug-resistant (MDR) cytomegalovirus (CMV) emerged after transient responses to ganciclovir, foscarnet, and cidofovir in a CMV-seropositive recipient who underwent allogeneic hematopoietic stem cell transplantation from a CMV-seronegative donor. Experimental treatments using leflunomide and artesunate failed. Re-transplantation from a CMV-seropositive donor supported by adoptive transfer of pp65-specific T cells and maribavir was followed by lasting suppression. This case illustrates that successful MDR CMV therapy may require individualized multidisciplinary approaches.

Strong Impact of Smoking on Multimorbidity and Cardiovascular Risk Among Human Immunodeficiency Virus-Infected Individuals in Comparison With the General Population.

Background. Although acquired immune deficiency syndrome-associated morbidity has diminished due to excellent viral control, multimorbidity may be increasing among human immunodeficiency virus (HIV)-infected persons compared with the general population. Methods. We assessed the prevalence of comorbidities and multimorbidity in participants of the Swiss HIV Cohort Study (SHCS) compared with the population-based CoLaus study and the primary care-based FIRE (Family Medicine ICPC-Research using Electronic Medical Records) records. The incidence of the respective endpoints were assessed among SHCS and CoLaus participants. Poisson regression models were adjusted for age, sex, body mass index, and smoking. Results. Overall, 74 291 participants contributed data to prevalence analyses (3230 HIV-infected; 71 061 controls). In CoLaus, FIRE, and SHCS, multimorbidity was present among 26%, 13%, and 27% of participants. Compared with nonsmoking individuals from CoLaus, the incidence of cardiovascular disease was elevated among smoking individuals but independent of HIV status (HIV-negative smoking: incidence rate ratio [IRR] = 1.7, 95% confidence interval [CI] = 1.2-2.5; HIV-positive smoking: IRR = 1.7, 95% CI = 1.1-2.6; HIV-positive nonsmoking: IRR = 0.79, 95% CI = 0.44-1.4). Compared with nonsmoking HIV-negative persons, multivariable Poisson regression identified associations of HIV infection with hypertension (nonsmoking: IRR = 1.9, 95% CI = 1.5-2.4; smoking: IRR = 2.0, 95% CI = 1.6-2.4), kidney (nonsmoking: IRR = 2.7, 95% CI = 1.9-3.8; smoking: IRR = 2.6, 95% CI = 1.9-3.6), and liver disease (nonsmoking: IRR = 1.8, 95% CI = 1.4-2.4; smoking: IRR = 1.7, 95% CI = 1.4-2.2). No evidence was found for an association of HIV-infection or smoking with diabetes mellitus. Conclusions. Multimorbidity is more prevalent and incident in HIV-positive compared with HIV-negative individuals. Smoking, but not HIV status, has a strong impact on cardiovascular risk and multimorbidity.

Increases in Condomless Sex in the Swiss HIV Cohort Study.

Condomless sex is a key driver of sexually transmitted diseases. In this study, we assess the long-term changes (2000-2013) of the occurrence of condomless sex among human immunodeficiency virus (HIV)-infected individuals enrolled in the Swiss HIV Cohort study. The frequencies with which HIV-infected individuals reported condomless sex were either stable or only weakly increasing for 2000-2008. For 2008-2013, these rates increased significantly for stable relationships among heterosexuals and men who have sex with men (MSM) and for occasional relationships among MSM. Our results highlight the increasing public health challenge posed by condomless sex and show that condomless sex has been increasing even in the most recent years.

Incident Hepatitis C Virus Infections in the Swiss HIV Cohort Study: Changes in Treatment Uptake and Outcomes Between 1991 and 2013.

Background. The hepatitis C virus (HCV) epidemic is evolving rapidly in patients infected with human immunodeficiency virus (HIV). We aimed to describe changes in treatment uptake and outcomes of incident HCV infections before and after 2006, the time-point at which major changes in HCV epidemic became apparent. Methods. We included all adults with an incident HCV infection before June 2012 in the Swiss HIV Cohort Study, a prospective nationwide representative cohort of individuals infected with HIV. We assessed the following outcomes by time period: the proportion of patients starting an HCV therapy, the proportion of treated patients achieving a sustained virological response (SVR), and the proportion of patients with persistent HCV infection during follow-up. Results. Of 193 patients with an HCV seroconversion, 106 were diagnosed before and 87 after January 2006. The proportion of men who have sex with men increased from 24% before to 85% after 2006 (P < .001). Hepatitis C virus treatment uptake increased from 33% before 2006 to 77% after 2006 (P < .001). Treatment was started during early infection in 22% of patients before and 91% after 2006 (P < .001). An SVR was achieved in 78% and 29% (P = .01) of patients treated during early and chronic HCV infection. The probability of having a detectable viral load 5 years after diagnosis was 0.67 (95% confidence interval [CI], 0.58-0.77) in the group diagnosed before 2006 and 0.24 (95% CI, 0.16-0.35) in the other group (P < .001). Conclusions. In recent years, increased uptake and earlier initiation of HCV therapy among patients with incident infections significantly reduced the proportion of patients with replicating HCV.

Current preventive strategies and management of Epstein-Barr virus-related post-transplant lymphoproliferative disease in solid organ transplantation in Europe. Results of the ESGICH Questionnaire-based Cross-sectional Survey.

There is limited clinical evidence on the utility of the monitoring of Epstein-Barr virus (EBV) DNAemia in the pre-emptive management of post-transplant lymphoproliferative disease (PTLD) in solid organ transplant (SOT) recipients. We investigated current preventive measures against EBV-related PTLD through a web-based questionnaire sent to 669 SOT programmes in 35 European countries. This study was performed on behalf of the ESGICH study group from the European Society of Clinical Microbiology and Infectious Diseases. A total of 71 SOT programmes from 15 European countries participated in the study. EBV serostatus of the recipient is routinely obtained in 69/71 centres (97%) and 64 (90%) have access to EBV DNAemia assays. EBV monitoring is routinely used in 85.9% of the programmes and 77.4% reported performing pre-emptive treatment for patients with significant EBV DNAemia levels. Pre-emptive treatment for EBV DNAemia included reduction of immunosuppression in 50.9%, switch to mammalian target of rapamycin inhibitors in 30.9%, and use of rituximab in 14.5% of programmes. Imaging by whole-body 18-fluoro-deoxyglucose positron emission tomography (FDG-PET) is used in 60.9% of centres to rule out PTLD and complemented computer tomography is used in 50%. In 10.9% of centres, FDG-PET is included in the first-line diagnostic workup in patients with high-risk EBV DNAemia. Despite the lack of definitive evidence, EBV load measurements are frequently used in Europe to guide diagnostic workup and pre-emptive reduction of immunosuppression. We need prospective and controlled studies to define the impact of EBV monitoring in reducing the risk of PTLD in SOT recipients.

Diffuse gastrointestinal bleeding and BK polyomavirus replication in a pediatric allogeneic haematopoietic stem cell transplant patient.

Patients undergoing haematopoietic stem cell transplantation (HSCT) are at high risk of severe gastrointestinal bleeding caused by infections, graft versus host disease, and disturbances in haemostasis. BK polyomavirus (BKPyV) is known to cause hemorrhagic cystitis, but there is also evidence of BKV shedding in stool and its association with gastrointestinal disease. We report putative association of BKPyV replication with high plasma viral loads in a pediatric HSCT patient developing hemorrhagic cystitis and severe gastrointestinal bleeding necessitating intensive care. The observation was based on chart review and analysis of BKPyV DNA loads in plasma and urine as well as retrospective BKPyV-specific IgM and IgG measurements in weekly samples until three months post-transplant. The gastrointestinal bleeding was observed after a >100-fold increase in the plasma BKPyV loads and the start of hemorrhagic cystitis. The BKPyV-specific antibody response indicated past infection prior to transplantation, but increasing IgG titers were seen following BKPyV replication. The gastrointestinal biopsies were taken at a late stage of the episode and were no longer informative of BK polyomavirus involvement. In conclusion, gastrointestinal complications with bleeding are a significant problem after allogeneic HSCT to which viral infections including BKPyV may contribute.

A case of primary JC polyomavirus infection-associated nephropathy.

A 15-year-old boy with a posterior urethral valve received a deceased donor kidney transplant (KT) in March 2011. Basiliximab induction followed by tacrolimus-based triple medication was used as immunosuppression. Eleven months after KT, the graft function deteriorated and the biopsy demonstrated interstitial nephritis suggestive of acute rejection. BK polyomavirus (BKPyV) surveillance in urine and plasma was negative. The patient received methylprednisolone pulses and anti-thymocyte globulin. Immunohistochemistry was positive for simian virus 40 (SV40) large T-antigen (LTag) in the biopsies, and quantitative polymerase chain reaction for JC polyomavirus (JCPyV) indicated high viral loads in urine and borderline levels in plasma. Immunosuppression was reduced and follow-up biopsies showed tubular atrophy and interstitial fibrosis. Two years after KT, antibody-mediated rejection resulted in graft loss and return to hemodialysis. Retrospective serologic work-up indicated a primary JCPyV infection with seroconversion first for IgM, followed by IgG, but no indication of BKPyV infection. In the SV40 LTag positive biopsies, JCPyV deoxyribonucleic acid (DNA) with archetype noncoding control region was detected, while BKPyV DNA was undetectable. To the best of our knowledge, this is the first reported case of primary JCPyV infection as the cause of PyV-associated nephropathy in KT.