Usefulness of quantitative real-time polymerase chain reaction in following up patients with Epstein-Barr virus infection after liver transplantation

Plasma EBV microRNAs in paediatric renal transplant recipients

BACKGROUND

Epstein-Barr virus (EBV) was the first human virus identified to express microRNA (miRNA). To date, 44 mature miRNAs are encoded for within the EBV genome. EBV miRNAs have not been profiled in paediatric renal transplant recipients. In this study, we investigated circulating EBV miRNA profiles as novel biomarkers in paediatric renal transplant patients.

METHODS

Forty-two microRNAs encoded within 2 EBV open reading frames (BART and BHRF) were examined in renal transplant recipients who resolved EBV infection (REI) or maintained chronic high viral loads (CHL), and in non-transplant patients with acute infectious mononucleosis (IM).

RESULTS

Plasma EBV-miR-BART2-5p was present in higher numbers of IM (7/8) and CHL (7/10) compared to REI (7/12) patients. A trend was observed between the numbers of plasma EBV miRNAs expressed and EBV viral load (p < 0.07). Several EBV-miRs including BART7-3p, 15, 9-3p, 11-3p, 1-3p and 3-3p were detected in IM and CHL patients only. The lytic EBV-miRs, BHRF1-2-3p and 1-1, indicating active viral replication, were detected in IM patients only. One CHL patient developed post-transplant lymphoproliferative disease (PTLD) after several years and analysis of 10 samples over a 30-month period showed an average 24-fold higher change in plasma EBV-miR-BART2-5p compared to the CHL group and 110-fold higher change compared to the REI group.

CONCLUSIONS

Our results suggest that EBV-miR-BART2-5p, which targets the stress-induced immune ligand MICB to escape recognition and elimination by NK cells, may have a role in sustaining high EBV viral loads in CHL paediatric kidney transplant recipients.

The Role of Antiviral Prophylaxis for the Prevention of Epstein-Barr Virus-Associated Posttransplant Lymphoproliferative Disease in Solid Organ Transplant Recipients: A Systematic Review

The role of antiviral prophylaxis for the prevention of posttransplant lymphoproliferative disease (PTLD) remains controversial for solid organ transplantation (SOT) recipients who are seronegative for Epstein-Barr virus (EBV) but who received organs from seropositive donors. We performed a systematic review and meta-analysis to address this issue. Two independent assessors extracted data from studies after determining patient eligibility and completing quality assessments. Overall, 31 studies were identified and included in the quantitative synthesis. Nine studies were included in the direct comparisons (total 2366 participants), and 22 were included in the indirect analysis. There was no significant difference in the rate of EBV-associated PTLD in SOT recipients among those who received prophylaxis (acyclovir, valacyclovir, ganciclovir, valganciclovir) compared with those who did not receive prophylaxis (nine studies; risk ratio 0.95, 95% confidence interval 0.58-1.54). No significant differences were noted across all types of organ transplants, age groups, or antiviral use as prophylaxis or preemptive therapy. There was no significant heterogeneity in the effect of antiviral prophylaxis on the incidence of PTLD. In conclusion, the use of antiviral prophylaxis in high-risk EBV-naive patients has no effect on the incidence of PTLD in SOT recipients.

The role of EBV in the pathogenesis of Burkitt's Lymphoma: an Italian hospital based survey

The exact worldwide incidence of Burkitt’s lymphoma is not known. There are three distinct clinical variants of Burkitt’s lymphoma, each manifesting differences in epidemiology, clinical presentation, morphology, biology and genetic features: the endemic (African), the sporadic (non-endemic), and the immunodeficiency-associated form. In particular, we reported data regarding Burkitt’s lymphoma incidence in the world and across different European countries. Finally, we described clinic-pathological data of 48 Burkitt’s lymphomas occurred in Italy from 2003 to 2013, in 4 different hospitals, two of which located in east side, and the other ones located in the west-coast. Forty Burkitt’s lymphomas occurs in children (age range 3–12), and 8 were adulthood Burkitt’s lymphomas (age range 18–87). In the pediatric group the Male:Female ratio (M:F) was of 4:1, whereas the group of the adult patients has a M:F of 1:1.67. Immunohistochemical detection of Latent Membrane Protein 1 (LMP1) expression and Epstein-Barr virus Encoded RNA (EBER) In Situ Hybridization (ISH) procedures have been performed. Lymphocyte B monoclonal spread has been demonstrated using a Polymerase Chain Reaction (PCR) based method to amplify Fragment Restriction FR1, FR2 and FR3 immunoglobulin heavy chains DNA fragments. Only 38 cases out of 48 were analyzed for LMP-1 showing various percentage of stained cells in 47.4% of the patients.

Considering ISH for EBER detection results:

1 out 2 (50%) adult analyzed cases was positive, with 50% of stained tumor cells (this patient was a 22 years old female, coming from Napoli);

15 out 24 (62.5%) children analyzed Burkitt’s lymphomas resulted as positive for EBER;

the overall positivity has been observed in 16/26 Burkitt’s lymphomas (61.53%).

Finally, EBV has been detected in children and adult patients, one of them with deregulation of the oncogene c-MYC by chromosomal translocation.

Rituximab therapy and reduction of immunosuppression to rescue graft function after renal posttransplantation lymphoproliferative disorder found by macrohematuria in a pancreas and kidney transplant recipient: a case report

INTRODUCTION

Posttransplantation lymphoproliferative disorder (PTLD) remains an uncommon complication of solid organ transplantation, with a high mortality rate reported after conventional therapies. Epstein-Barr virus (EBV) may cause PTLD, but most EBV infections after transplantation are clinically silent reactivations, so the detection of PTLD is often delayed. Recently we experienced the rare case of intrarenal graft PTLD found by macrohematuria in a simultaneous pancreas and kidney transplant recipient. The grafts were saved by treatments with rituximab, cyclophosphamide, hydroxydaunorubicin, and prednisone-based chemotherapy (R-CHOP) after reduction of immunosuppression (IR).

METHODS

This 37-year-old man with insulin-dependent diabetes underwent simultaneous pancreas and kidney transplantation (SPK) with enteric drainage. Six months after transplantation, he displayed macrohematuria, which we investigated by blood tests, computer tomography (CT) scan, positron emission tomography (PET)-CT, and magnetic resonance imaging, recognizing a tumor in the transplanted renal graft. An open biopsy showed a CD20-positive PTLD. We started treatments with IR, rituximab (375 mg/m(2), weekly for 2 cycles) and R-CHOP therapy: rituximab (375 mg/m(2)) plus CHOP every 3 weeks for 6 cycles.

RESULTS

IR and R-CHOP therapy achieved a complete remission (CR). CR has continued for 14 months at the time of writing. The maximum level of EBV DNA was 259 copies/μg DNA, but 2 months after these therapies, the level had decreased to normal. The patient had no impairment of pancreas and kidney graft functions.

CONCLUSIONS

The outcome of intragraft PTLD in the kidney of an SPK recipient suggested that the negative impact of IR on graft function may be compensated by the immunosuppressive effects of rituximab, allowing reduced immunosuppression during chemotherapy.

Burkitt's Lymphoma Presenting as Late-Onset Posttransplant Lymphoproliferative Disorder following Kidney and Pancreas Transplantation: Case Report and Review of the Literature

Posttransplant lymphoproliferative disorders (PTLD) are a rare, but serious complication following transplantation. Late-onset PTLD are often associated with more monoclonal lesions and consequently have a worse prognosis. There are only isolated case reports of Burkitt's lymphoma presenting as PTLD. We present an extremely rare, aggressive Burkitt's lymphoma years after kidney and pancreas transplantation which was successfully treated with combination chemotherapy along with withdrawal of immunosuppression. The patient remains in complete remission more than 2 years after his diagnosis. We also provide a succinct review of treatment of various PTLD and discuss the role of Epstein-Barr virus infection in the pathogenesis of PTLD.

Using Epstein-Barr viral load assays to diagnose, monitor, and prevent posttransplant lymphoproliferative disorder

Epstein-Barr virus (EBV) DNA measurement is being incorporated into routine medical practice to help diagnose, monitor, and predict posttransplant lymphoproliferative disorder (PTLD) in immunocompromised graft recipients. PTLD is an aggressive neoplasm that almost always harbors EBV DNA within the neoplastic lymphocytes, and it is often fatal if not recognized and treated promptly. Validated protocols, commercial reagents, and automated instruments facilitate implementation of EBV load assays by real-time PCR. When applied to either whole blood or plasma, EBV DNA levels reflect clinical status with respect to EBV-related neoplasia. While many healthy transplant recipients have low viral loads, high EBV loads are strongly associated with current or impending PTLD. Complementary laboratory assays as well as histopathologic examination of lesional tissue help in interpreting modest elevations in viral load. Circulating EBV levels in serial samples reflect changes in tumor burden and represent an effective, noninvasive tool for monitoring the efficacy of therapy. In high-risk patients, serial testing permits early clinical intervention to prevent progression toward frank PTLD. Restoring T cell immunity against EBV is a major strategy for overcoming PTLD, and novel EBV-directed therapies are being explored to thwart virus-driven neoplasia.

Significance of Epstein-Barr virus (EBV) load and Interleukin-10 in post-transplant lymphoproliferative disorders

The complex relationship between EBV, IL-10 and lymphomagenesis has been widely investigated and several studies have highlighted the diagnostic value of EBV DNA copies and serum IL-10, that may be considered as tumor markers. Notwithstanding the great number of data published in the last few years on the behavior of EBV DNA copies in the peripheral blood of transplanted patients, a threshold value significant for impending or overt post-transplant lymphoproliferative disorder (PTLD) has not yet been defined. Too many factors, both technical and clinicopathological, may affect the results of clinical studies, making their comparison difficult. On the contrary, although the role of IL-10 in PTLDs has been well documented, a sufficient number of studies exploring sensitivity and specificity of serum IL-10 measurement is lacking. The aim of this review is to summarise data on EBV load quantification and serum IL-10 detection in transplanted patients, providing clinicians with wide and useful information in order to improve bedside management of transplanted patients with regard to PTLDs occurrence and treatment.

Associations of serum EBV DNA and gammopathy with post-transplant lymphoproliferative disease

BACKGROUND

Post-transplant lymphoproliferative disease (PTLD) is a life-threatening complication of immunosuppression following transplantation. Epstein-Barr virus (EBV) and gammopathy in serum are associated with PTLD, but these two parameters have not been evaluated in parallel for their association with PTLD.

METHODS

We evaluated the incidence of EBV load positivity, gammopathy, and protein expression in sera from all PTLD patients diagnosed at our hospital during the past seven yr. Results were compared with those of a control group including matched transplanted patients who did not develop PTLD.

RESULTS

Seven of 10 PTLD patients presented EBV(+) PTLD, for which five patients had detectable serum EBV DNA levels compared with none of 38 controls (RR between two groups =121, p < 0.0001). Five out of 10 patients had gammopathy at PTLD diagnosis compared with 5/38 controls (RR between two groups = 6.6, p = 0.022). Additionally, protein serum analysis by high-resolution two-dimensional gel electrophoresis and image examination failed to evidence specific abnormality in patients with PTLD compared with controls.

CONCLUSIONS

Our results confirm an association between EBV in sera and gammopathy with PTLD, and highlight the high specificity of the former analysis. Whether a combination of both analyses will improve the clinical detection of PTLD remains to be evaluated in a larger prospective cohort study.

Simultaneous monitoring by real-time polymerase chain reaction of epstein-barr virus, human cytomegalovirus, and human herpesvirus-6 in juvenile and adult liver transplant recipients

Cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human herpesvirus-6 (HHV-6) cause symptomatic diseases in liver transplant recipients. The loads of these viruses, the associations between viral DNAemia, serologic status, and acute rejection reactions were investigated in a group of 17 juvenile and 17 adult recipients of living donor liver transplantation (LDLT) for a median of 8 weeks posttransplantation. At least 1 plasma sample from 15/34 (44.1%) patients was positive for CMV DNA. For most of the CMV-positive patients, the CMV DNA appeared in the second week of LDLT, and disappeared by the eighth week. A minimum of 200 EBV DNA copies/mug peripheral blood mononuclear cell DNA (defined as positive for EBV) was detected in 5/34 (14.7%) patients, and the number of EBV-positive children was significantly greater than the number of EBV-positive adults. In most of the EBV-positive patients, the EBV loads increased after 4 weeks posttransplantation. Plasma HHV-6 was detected in 7/34 (20.6%) patients. HHV-6 DNA appeared for a short period from the second week of LDLT. In addition, 8 of the 19 virus-positive recipients carried 2 viruses, with the combination of CMV and HHV-6 being the most frequent. Serologic status seemed to be an important factor for all 3 viral infections. The rate of acute cellular rejection was not significantly higher in the CMV-, EBV-, or HHV-6-positive groups. Simultaneous monitoring for 3 herpesviruses revealed the impact of these viruses on LDLT recipients.

Monitoring of Epstein-Barr virus load after hematopoietic stem cell transplantation for early intervention in post-transplant lymphoproliferative disease

Epstein-Barr virus (EBV)-associated post-transplant lymphoproliferative disease is a life-threatening complication following hematopoietic stem cell transplantation. A quantitative polymerase chain reaction to evaluate EBV-genome copy numbers based on a nested polymerase chain reaction and an end-point dilution was used. Applying this assay EBV load was prospectively screened weekly in 123 patients after transplantation. The results demonstrate that EBV reactivations with more than 1,000 EBV-genome copies measured in 10(5) peripheral blood mononuclear cells were observed in 31 patients (25.2%). Three patients developed lymphoproliferative disease with extremely high EBV-genome copies in peripheral blood mononuclear cells (>100,000 copies/10(5) cells) and plasma. After combined antiviral and immune therapy two of three patients showed a dramatic decrease of EBV load and survived, while the third patient died of lymphoma. A subclinical EBV reactivation was observed in 24 cases (19.5%) with EBV-genome copies in 10(5) peripheral blood mononuclear cells ranging between 2,500 and mostly 10,000. After reduction of immunosuppression the EBV levels normalized. In four patients, the high copy number of > or =80,000 copies/10(5) peripheral blood mononuclear cells and plasma positivity prompted us to start pre-emptive therapy with rituximab and cidofovir for prevention of lymphoproliferative disease. After drug administration the high EBV load was reduced remarkably. Ninety-two patients (74.8%) who had < or =1,000 copies/10(5) peripheral blood mononuclear cells did not develop EBV-associated lymphoproliferative disease. In conclusion, monitoring of EBV load is a sensitive and useful parameter in the surveillance of EBV reactivation for early intervention in EBV-associated lymphoproliferative disease as well as for follow-up of the efficacy of therapy.

Monitoring of EBV-DNAemia by quantitative real-time PCR after adult liver transplantation

BACKGROUND

Post-transplant lymphoproliferative disease (PTLD) causes significant morbidity and mortality in transplantation. The clinical significance of Epstein-Barr virus (EBV) in the development of PTLD is clear, but not all EBV-reactivations cause PTLD.

OBJECTIVES

We retrospectively analyzed EBV-DNAemia in liver transplant patients by a quantitative TaqMan-based real-time plasma PCR.

STUDY DESIGN

Altogether 1284 specimens, obtained from 105 patients for frequent monitoring of cytomegalovirus (CMV) and human herpesvirus-6 and -7 (HHV-6, HHV-7) during the post-transplant year, were retrospectively tested for EBV-DNA.

RESULTS

Altogether, 14/105 (13%) patients showed EBV-DNAemia, which usually occurred within 3 months after transplantation and subsided within a few weeks. EBV-DNAemia occurred concurrently with CMV in 10/14, with HHV-6 in 11/14, and with all three betaherpesviruses in 4/14 cases. The peak viral loads were relatively low (median 2100 EBV-DNA copies/ml, range 568-6600), except in one patient who first had low-level EBV-DNA (562-3022 copies/ml) in the early post-transplant period, but on day 175 after transplantation developed high-level DNAemia (9851-86,975copies/ml) which continued for 6 months and developed into PTLD at 6 months after transplantation.

CONCLUSION

Low-level EBV-DNAemia is common after liver transplantation, often occurring together with betaherpesviruses, but seldom leads to high viral loads or PTLD. However, monitoring of EBV-DNA levels in the patients can be useful.

Detection and monitoring of virus infections by real-time PCR

The employment of polymerase chain reaction (PCR) techniques for virus detection and quantification offers the advantages of high sensitivity and reproducibility, combined with an extremely broad dynamic range. A number of qualitative and quantitative PCR virus assays have been described, but commercial PCR kits are available for quantitative analysis of a limited number of clinically important viruses only. In addition to permitting the assessment of viral load at a given time point, quantitative PCR tests offer the possibility of determining the dynamics of virus proliferation, monitoring of the response to treatment and, in viruses displaying persistence in defined cell types, distinction between latent and active infection. Moreover, from a technical point of view, the employment of sequential quantitative PCR assays in virus monitoring helps identifying false positive results caused by inadvertent contamination of samples with traces of viral nucleic acids or PCR products. In this review, we provide a survey of the current state-of-the-art in the application of the real-time PCR technology to virus analysis. Advantages and limitations of the RQ-PCR methodology, and quality control issues related to standardization and validation of diagnostic assays are discussed.

Epstein-Barr viremia levels after pediatric liver transplantation as measured by real-time polymerase chain reaction

Effective immunosuppression has improved the results following liver transplantation, but also increased the risk for opportunistic infections. Epstein-Barr virus (EBV) infection in transplant patients can cause various symptoms including the life-threatening premalignant condition, post-transplantation lymphoproliferative disorder (PTLD). Serum specimens from 24 consecutive children (mean 7.6 specimens/patient), who had undergone liver transplantation in Göteborg from January 1995 to May 2002, were analyzed retrospectively for EBV DNA by real-time TaqMan polymerase chain reaction (PCR). The results were related to clinical picture, immunosuppression, graft rejection and infections with other agents. Eleven patients (46%) developed primary EBV infection at a mean time of 4.8 months after transplantation, and six (25%) reactivated EBV infection at a mean of 4.0 months after transplantation. Four of the 11 patients with primary infection had symptomatic EBV infection: two had PTLD and two hepatitis. One patient in the group with reactivated infection developed PTLD. EBV DNA levels were significantly higher in the group with primary symptomatic infection compared with the patients with primary asymptomatic infection (mean 65 500 copies/mL; range 14 200-194 300 vs. 3700 copies/mL; range 100-9780). In patients with symptomatic infection EBV DNA levels did not differ between PTLD and hepatitis patients. The data suggest that quantitative analysis of EBV DNA in serum by real-time PCR is useful for identification of EBV-related disease.

Real-time PCR in clinical microbiology: applications for routine laboratory testing

Real-time PCR has revolutionized the way clinical microbiology laboratories diagnose many human microbial infections. This testing method combines PCR chemistry with fluorescent probe detection of amplified product in the same reaction vessel. In general, both PCR and amplified product detection are completed in an hour or less, which is considerably faster than conventional PCR detection methods. Real-time PCR assays provide sensitivity and specificity equivalent to that of conventional PCR combined with Southern blot analysis, and since amplification and detection steps are performed in the same closed vessel, the risk of releasing amplified nucleic acids into the environment is negligible. The combination of excellent sensitivity and specificity, low contamination risk, and speed has made real-time PCR technology an appealing alternative to culture- or immunoassay-based testing methods for diagnosing many infectious diseases. This review focuses on the application of real-time PCR in the clinical microbiology laboratory.

Dynamic EBV gene loads in renal, hepatic, and cardiothoracic transplant recipients as determined by real-time PCR light cycler

BACKGROUND

Epstein-Barr virus (EBV) is recognised as one of the causative agents for most cases of post-transplant lymphoproliferative disease (PTLD). Elevated levels of EBV DNA are known to be associated with the onset of PTLD, but little information is available regarding how EBV loads change with time in asymptomatic transplant recipients following transplantation. Our aims were to study the trend of EBV loads in renal (RTx), hepatic, and cardiothoracic transplant recipients and to compare their EBV loads with other healthy and patient controls.

METHODS

A prospective study was performed using a real-time TaqMan polymerase chain reaction technique to measure EBV DNA loads from three types of organ transplant recipients and haemodialysis patients (HD). Their results were then compared with those from the healthy controls (HC); monospot test negative (MN-) and infectious mononucleosis positive (IM+) patients; patients who were previously treated for PTLD (pPTLD); those who were currently diagnosed to have PTLD (PTLD+); and patients who had a stable renal, hepatic, or cardiothoracic graft for more than a year.

RESULTS

Post-transplant EBV loads were significantly higher than the pre-transplant levels. Asymptomatic transplant recipients were differentiated from the PTLD+group at 600 genome copies of EBV/mug DNA, and from IM+group at 100 genome copies. Both HC and MN- groups had significantly lower EBV loads than the three transplant groups. The dynamic change of EBV loads in RTx was greater in the first post-transplant month when compared with the HD group. All transplant recipients had transient rises of EBV loads whereas EBV load continued to rise in one suspected PTLD patient.

CONCLUSIONS

Asymptomatic transplant recipients had higher baseline post-transplant EBV levels than the non-transplant and MN- groups. The rising post-transplant EBV load in these transplant recipients did not seem to be sustained for longer than 2 weeks. However, in a PTLD+patient the rising EBV load continued over a period of 4 weeks. Hence, the dynamic pattern of EBV loads is more important than absolute EBV DNA measurements alone in identifying those who might go on to develop PTLD.

Assessment of automated DNA extraction coupled with real-time PCR for measuring Epstein-Barr virus load in whole blood, peripheral mononuclear cells and plasma

BACKGROUND

Epstein-Barr virus (EBV) DNA load monitoring in blood has been shown to be essential for the diagnosis of EBV-associated diseases. However, the methods currently used to assess EBV DNA load are often time-consuming and require prior blood separation.

OBJECTIVES

The aim of this study was to evaluate the relative diagnostic value of EBV DNA load monitoring in whole blood, peripheral blood mononuclear cells (PBMCs) and plasma after automated DNA extraction using the MagNA Pure extractor followed by LightCycler real-time quantitative PCR (LC-PCR).

STUDY DESIGN

First, EBV DNA load was assessed retrospectively after automated or manual extraction on 104 PBMC specimens. Second, EBV DNA load was determined prospectively with the automated extraction procedure in the whole blood, PBMCs and plasma of 100 samples from patients with EBV-related diseases (group 1, n = 20), HIV-seropositive individuals (group 2, n = 66), and healthy EBV carriers (group 3, n = 14).

RESULTS

A good correlation was observed between automated and manual extraction on 104 PBMC specimens (r = 0.956; P < 0.0001). In the prospective study, 67 samples were positive in both whole blood and PBMCs, with a good correlation between EBV DNA loads in whole blood and PBMCs (r = 0.936; P < 0.0001). Only 18/100 samples were positive in plasma. Higher viral loads were regularly observed in the three blood compartments from group 1 than from groups 2 and 3.

CONCLUSION

This study demonstrated that an automated extraction of EBV DNA is easier to perform in whole blood or plasma than in PBMCs and facilitates the standardisation of EBV DNA measurement by real-time quantitative PCR. The quantitative detection of EBV DNA load in whole blood appeared more sensitive than in plasma for infectious mononucleosis in immunocompetent patients, probably because of a rapid loss of plasmatic EBV DNA. In transplant patients, EBV DNA load monitoring in whole blood and in plasma turned out to be equivalent in terms of feasibility and accuracy for the early diagnosis of post-transplant lymphoproliferative diseases (PTLDs).

Development of real-time PCR assays for the quantitative detection of Epstein-Barr virus and cytomegalovirus, comparison of TaqMan probes, and molecular beacons

Human Epstein-Barr virus (EBV) and cytomegalovirus (CMV) can cause serious complications in immunocompromised patients. Rapid diagnosis of EBV and CMV infection is critical in the management of the disease so that anti-viral therapy can be started early. Here we describe the development of real-time PCR assays using TaqMan probes and molecular beacons and compare the performance of both assays with a well-established, validated, gel-based PCR method for the quantification of EBV and CMV in patients' samples. The TaqMan and molecular beacon assays were linear between 10 to 10(7) viral genomes/reaction. Both assays generated calibration curves with strong correlation and low intra-assay and interassay variation. Results of EBV and CMV viral load determination inpatient samples obtained by the gel-based and real-time PCR were very similar. The real-time PCR assays showed increases in viral load before clinical measures of viral disease and decreases in viral load during anti-viral therapy in two of six pediatric patients. The data indicate that these TaqMan and molecular beacon approaches are accurate, rapid, and reliable assays for the diagnosis and monitoring of EBV and CMV infections in patients.

Quantitative tissue polymerase chain reaction for Epstein-Barr virus in pediatric solid organ recipients

BACKGROUND

Infections caused by herpes virus, in particular, Epstein-Barr virus (EBV), remain a major challenge in solid organ transplantation. Little is known about the significance of tissue EBV load.

METHODS

Twenty-three tissue biopsy specimens (19 kidney, 3 gastrointestinal, and 1 tonsil specimen) and 2 bronchoalveolar lavage specimens from 14 pediatric transplant recipients (10 kidney, 3 liver, 1 combined transplant) were subject to tissue EBV polymerase chain reaction (PCR) semiquantitative analysis and enzyme-linked immunosorbent assay (ELISA) methods. Results of biopsies were correlated with clinical data.

RESULTS

Five of 14 patients had clinically diagnosed EBV disease: 2 patients presented with a septic picture with multiorgan failure and pneumonitis; 1 patient had mononucleosis; 1 patient had an increase in serum creatinine level, lymphadenopathy, and chronic fatigue; and 1 patient had EBV nephritis. These 5 patients underwent 12 biopsies at the time of clinically active infection; 8 biopsies had positive results (up to 111 copies/10 microL of extracted DNA). Conversely, 1 of the remaining 13 tissue biopsy specimens from asymptomatic patients had positive results on ELISA, but undetectable viral load, whereas 8 patients had a positive EBV immunoglobulin G titer with historic evidence of EBV replication in the blood. No patient without evidence of EBV had positive EBV tissue PCR results.

CONCLUSION

Increased EBV load was found in more than 50% of patients, pointing to a previously underrecognized importance of EBV detection in tissues from transplant recipients. The presence of EBV in tissue correlated with the presence of viremia, whereas tissue PCR had 100% specificity. EBV load should be included in biopsy evaluation.

Overview of Epstein-Barr virus-associated diseases in Japan

Epstein-Barr virus (EBV) associated diseases and studies performed in Japan are reviewed. Infectious mononucleosis is a common disease in Japanese infants. Chronic and severe EBV-infections include severe chronic active EBV-infection (SCAEBV), EBV-associated hemophagocytic syndrome, and mosquito allergy with granular lymphocyte proliferative disorder (GLPD). Autoimmune lymphoproliferative syndrome (ALPS), a disease caused by a defect in the Fas-Fas ligand pathway of cell-death, may develop into lymphoproliferative disease after early exposure to EBV. More than ten cases of X-linked lymphoproliferative syndrome (XLP) were discovered in Japanese children, and the frequency of post-transplant lymphoproliferative disorder (PTLD) increased after the number of patients receiving organ transplantation increased. Recently, an association of EBV with gastric carcinoma and hepatocellular carcinoma has been suggested. EBV-infected cells, such as B-cells, T-cells, NK-cells, and epithelial cells in EBV-associated diseases have also been clarified.

Epstein-Barr virus and post-transplant lymphoproliferative disease

There is convincing evidence that Epstein-Barr virus (EBV) is associated with post-transplant lymphoproliferative disease (PTLD). Primary EBV infection following transplantation occurs in as many as 90% of cases of PTLD in children and pretransplant EBV seronegativity is a recognized risk factor for developing PTLD. Other risk factors include young age at the time of transplant, the type of transplant that the recipient receives and the type and intensity of immunosuppression. The clinical presentation is often nonspecific and tissue biopsy is necessary to establish the diagnosis. There appears to be a correlation between PTLD and EBV viral load measured by polymerase chain reaction (PCR) of the peripheral blood and quantitative PCR may be a useful guide in the management of PTLD. Antiviral drugs and cytomegalovirus-immunoglobulin G may have a role in preventing PTLD. Because PTLD results from functional over-immunosuppression, the initial treatment is reduction of immunosuppression. Antiviral agents, interferon, immuno-based monoclonal therapy, cell-based therapy and chemotherapy also have a potential role in treating this disorder. At the present time there is no standardized approach to the evaluation and treatment of PTLD.

Quantitation of viral DNA in renal allograft tissue from patients with BK virus nephropathy

BACKGROUND

BK virus (BKV) allograft nephropathy (BKVAN) is a complication in renal transplantation recipients. Histopathology is the gold standard for diagnosis. Quantitative polymerase chain reaction (PCR) assay for renal biopsy has not been evaluated as a diagnostic test. Determination of renal BKV load may identify patients at risk for disease before histologic nephropathy.

METHODS

Quantitative PCR assay for BKV DNA was performed in 28 biopsies of patients with BKVAN; 50 biopsies were performed before a diagnosis of BKVAN, and 126 control biopsies were from patients without a history of BKVAN.

RESULTS

BKV DNA was present in 19 of 50 (38%) biopsies performed 1 to 164 weeks before diagnosis of BKVAN. The viral load (mean 216 copies/cell) was lower than in biopsies of patients with BKVAN (mean 6063 viral copies/cell, <0.05). In 10 of 127 (7.8%) control biopsies, a low level of BKV DNA (mean 3.8 copies/cell) was found in three biopsies from chronic allograft nephropathy patients; two biopsies with acute rejection; four biopsies with borderline change; and one biopsy with cytomegalovirus nephritis.

CONCLUSION

BKV load exceeding 59 copies per cell identified all cases of BKVAN. The diagnostic sensitivity, specificity, positive predictive value, and negative predictive value of quantitative PCR were 100%, 92.1%, 73.6%, and 100%, respectively. Lower levels of BKV DNA were identified in biopsies performed before viral nephropathy development. Future research will determine if earlier recognition of at-risk patients allows application of antiviral strategies to improve graft outcome.

Role of Epstein-Barr virus DNA load monitoring in prevention and early detection of post-transplant lymphoproliferative disease

Posttransplant lymphoproliferative disease (PTLD) is a severe and life-threatening complication after stem cell or solid-organ transplantation, virtually always associated with presence of Epstein-Barr virus (EBV) in the proliferating cells. PTLD is probably caused by the iatrogenically impaired T-cell response allowing outgrowth of EBV-positive B-cells. Quantitative EBV DNA load monitoring is a minimally invasive technique increasingly recognized as a valuable tool in posttransplant patient management. In this review, we focus on the clinical utility of EBV DNA load monitoring in the peripheral blood of transplant recipients using PCR and we discuss the currently most-widely used techniques and their value and limitations in predicting and diagnosing PTLD. Options for EBV DNA load-guided pre-emptive therapy and application of monitoring EBV DNA load dynamics in the prediction of clinical response after therapy are described. Origins of elevated EBV DNA loads in immunosuppressed patients and recent insights in the EBV life cycle in the immuncompromised host are discussed. Finally, a standardization of methodology, clinical specimen type, and cut-off values is proposed. This is essential for comparisons between different institutes and more adequate patient management.

A rapid monitoring system of human herpesviruses reactivation by LightCycler in stem cell transplantation

To establish a practical monitoring system of human herpesviruses reactivation in patients undergoing stem cell transplantation, we developed a new, very rapid, highly sensitive, and quantitative PCR assay for accurate measurement of human cytomegalovirus (CMV), human herpesvirus 6 (HHV-6) and Epstein-Barr virus (EBV) DNA using LightCycler. The LightCycler system revealed that there was a linear correlation in the wide range of viral template DNA at the indicated number of PCR cycles. Peripheral blood cells were collected from 16 patients undergoing stem cell transplantation. The cut-off level of CMV and HHV-6 was assessed as 10(2) copies/microg and that of EBV as 10(3). High numbers of CMV genomes were detected in 3/13 patients after transplant, and reactivation of HHV-6 was frequently seen, whereas none of the patient showed an elevation of EBV genome copies until the end of the observation period. In the present study, the reactivation of beta herpesviruses is associated with the occurrence of thrombotic microangiopathy (TMA) in two patients undergoing allogeneic BMT. Therefore, it may contribute in clarifying the pathological potential of human herpesviruses using a large number of clinical samples. Our results suggest that this system may be useful for monitoring viral reactivation.

Prospective monitoring of the Epstein-Barr virus DNA by a real-time quantitative polymerase chain reaction after allogenic stem cell transplantation

Epstein-Barr virus (EBV)-related lymphoproliferative disorder (LPD) is a serious complication of haematopoietic stem cell transplantation (HSCT). To clarify the frequency, natural course and risk factors for LPD, we prospectively monitored 38 allogeneic (allo)-HSCT patients, focusing on the use of anti-thymocyte globulin (ATG). We used a recently developed real-time polymerase chain reaction assay to monitor EBV genome load. The subjects consisted of 19 patients given ATG for conditioning and 19 patients not given ATG. Of the 19 patients given ATG, 47.4% (nine patients) had a significant increase in EBV genome load (10(2.5) copies/microg DNA). Of these nine patients, two developed LPD. Therefore, 10.5% of the patients receiving allo-HSCT with ATG developed LPD. In contrast, none of the 19 patients without ATG had a significantly increased EBV load. The increases in viral load were observed in the second or third month after HSCT. We found that the peak viral loads of LPD patients were > 10(4.0 ) copies/microg DNA. On the other hand, the viral loads of most patients with no symptoms were < 10(2.5) copies/microg DNA. In conclusion, routine monitoring of EBV load during the second and third months after transplantation may benefit patients undergoing HSCT with ATG. We propose that an EBV load > 10(2.5) copies/microg DNA is the reactivation of EBV, and that an EBV load > 10(4.0) copies/microg DNA is indicative of developing LPD.

Clinical utility of viral quantification as a tool for disease monitoring

The possibility to detect viral DNA or RNA in a quantitative manner has already contributed significantly to the management and diagnosis of viral infections, as well as to the understanding of virus-host interactions. New developments in amplification techniques based on real-time detection, as well as automation of the whole process, will soon be introduced in a diagnostic laboratory setting, thereby enabling a rapid turnaround time to generate both quantitative and qualitative results. New guidelines for disease management, as well as extensive quality control and standardization programs must be introduced.