The Second International Consensus Guidelines on the Management of BK Polyomavirus in Kidney Transplantation.

BK polyomavirus (BKPyV) remains a significant challenge after kidney transplantation. International experts reviewed current evidence and updated recommendations according to Grading of Recommendations, Assessment, Development, and Evaluations (GRADE). Risk factors for BKPyV-DNAemia and biopsy-proven BKPyV-nephropathy include recipient older age, male sex, donor BKPyV-viruria, BKPyV-seropositive donor/-seronegative recipient, tacrolimus, acute rejection, and higher steroid exposure. To facilitate early intervention with limited allograft damage, all kidney transplant recipients should be screened monthly for plasma BKPyV-DNAemia loads until month 9, then every 3 mo until 2 y posttransplant (3 y for children). In resource-limited settings, urine cytology screening at similar time points can exclude BKPyV-nephropathy, and testing for plasma BKPyV-DNAemia when decoy cells are detectable. For patients with BKPyV-DNAemia loads persisting >1000 copies/mL, or exceeding 10 000 copies/mL (or equivalent), or with biopsy-proven BKPyV-nephropathy, immunosuppression should be reduced according to predefined steps targeting antiproliferative drugs, calcineurin inhibitors, or both. In adults without graft dysfunction, kidney allograft biopsy is not required unless the immunological risk is high. For children with persisting BKPyV-DNAemia, allograft biopsy may be considered even without graft dysfunction. Allograft biopsies should be interpreted in the context of all clinical and laboratory findings, including plasma BKPyV-DNAemia. Immunohistochemistry is preferred for diagnosing biopsy-proven BKPyV-nephropathy. Routine screening using the proposed strategies is cost-effective, improves clinical outcomes and quality of life. Kidney retransplantation subsequent to BKPyV-nephropathy is feasible in otherwise eligible recipients if BKPyV-DNAemia is undetectable; routine graft nephrectomy is not recommended. Current studies do not support the usage of leflunomide, cidofovir, quinolones, or IVIGs. Patients considered for experimental treatments (antivirals, vaccines, neutralizing antibodies, and adoptive T cells) should be enrolled in clinical trials.

Wait Time Advantage for Transplant Candidates With HIV Who Accept Kidneys From Donors With HIV Under the HOPE Act.

BACKGROUND: Kidney transplant (KT) candidates with HIV face higher mortality on the waitlist compared with candidates without HIV. Because the HIV Organ Policy Equity (HOPE) Act has expanded the donor pool to allow donors with HIV (D + ), it is crucial to understand whether this has impacted transplant rates for this population. METHODS: Using a linkage between the HOPE in Action trial (NCT03500315) and Scientific Registry of Transplant Recipients, we identified 324 candidates listed for D + kidneys (HOPE) compared with 46 025 candidates not listed for D + kidneys (non-HOPE) at the same centers between April 26, 2018, and May 24, 2022. We characterized KT rate, KT type (D + , false-positive [FP; donor with false-positive HIV testing], D - [donor without HIV], living donor [LD]) and quantified the association between HOPE enrollment and KT rate using multivariable Cox regression with center-level clustering; HOPE was a time-varying exposure. RESULTS: HOPE candidates were more likely male individuals (79% versus 62%), Black (73% versus 35%), and publicly insured (71% versus 52%; P < 0.001). Within 4.5 y, 70% of HOPE candidates received a KT (41% D + , 34% D - , 20% FP, 4% LD) versus 43% of non-HOPE candidates (74% D - , 26% LD). Conversely, 22% of HOPE candidates versus 39% of non-HOPE candidates died or were removed from the waitlist. Median KT wait time was 10.3 mo for HOPE versus 60.8 mo for non-HOPE candidates ( P < 0.001). After adjustment, HOPE candidates had a 3.30-fold higher KT rate (adjusted hazard ratio = 3.30, 95% confidence interval, 2.14-5.10; P < 0.001). CONCLUSIONS: Listing for D + kidneys within HOPE trials was associated with a higher KT rate and shorter wait time, supporting the expansion of this practice for candidates with HIV.

HIV-Positive Liver Transplant Does not Alter the Latent Viral Reservoir in Recipients With Antiretroviral Therapy-Suppressed HIV.

The latent viral reservoir (LVR) remains a major barrier to HIV-1 curative strategies. It is unknown whether receiving a liver transplant from a donor with HIV might lead to an increase in the LVR because the liver is a large lymphoid organ. We found no differences in intact provirus, defective provirus, or the ratio of intact to defective provirus between recipients with ART-suppressed HIV who received a liver from a donor with (n = 19) or without HIV (n = 10). All measures remained stable from baseline by 1 year posttransplant. These data demonstrate that the LVR is stable after liver transplantation in people with HIV. Clinical Trials Registration. NCT02602262 and NCT03734393.

An Unusual Presentation of Metastatic BK Virus-Associated Urothelial Carcinoma Arising in the Allograft, Persisting After Transplant Nephrectomy.

We report a 32-year-old male 14 years post-living-related kidney transplant presenting with new-onset hematuria and BK viremia. He was found to have BK virus-associated urothelial carcinoma originating in the renal allograft with locally advanced disease and metastases to multiple sites. He also developed acute T-cell-mediated rejection in the setting of immunosuppression reduction for BK viremia prior to undergoing transplant nephrectomy. Eight months following transplant nephrectomy and immunosuppression cessation, distant metastases persisted with partial response to chemotherapy and immunotherapy. Here, we discuss this unique presentation and compare it with other BK virus-associated allograft carcinomas reported in the literature, in addition to discussing evidence for the role of BK virus in oncogenesis.

Short-term kidney transplant outcomes from severe acute respiratory syndrome coronavirus 2 lower respiratory tract positive donors.

OBJECTIVE: In this study, we aim to assess short-term allograft outcomes following deceased donor kidney transplantation from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lower respiratory tract (LRT) nucleic acid testing (NAT) positive donors. METHODS: From September to December 2021, SARS-CoV-2 NAT positive organ donors, whose solid abdominal organs were transplanted at our academic medical center were identified. Donors were stratified into having tested positive for SARS-CoV-2 in an upper respiratory tract (URT) or LRT sample. For this study, the SARS-CoV-2 LRT NAT positive deceased kidney donors and their respective recipients were examined. Donor and recipient demographic data, coronavirus disease 2019 (COVID-19)-related history, patient outcomes, as well as postoperative graft function were evaluated. RESULTS: Thirteen SARS-CoV-2 positive deceased donors were identified. Of these, eight were LRT NAT positive and yielded nine kidneys. These allografts were successfully transplanted into vaccinated and unvaccinated recipients. All recipients received standard induction immunosuppression and did not receive any prophylactic therapy for SARS-CoV-2. Two recipients had delayed graft function. At 1-month post-transplant, there was no clinical evidence of donor-derived COVID-19 or graft loss, and all recipients were free from dialysis. CONCLUSION: We describe the first case series of SARS-CoV-2 LRT NAT positive deceased kidney donors for vaccinated and unvaccinated recipients with excellent short-term allograft outcomes and no clinical evidence of donor-derived COVID-19 post-transplantation. Given the increasing prevalence of SARS-CoV-2 in the population, utilization of SARS-CoV-2 LRT NAT positive deceased donors could be considered an acceptable source of organs for renal transplantation, especially as multi-center experiences and longer-term follow-up emerge.

HOPE in action: A prospective multicenter pilot study of liver transplantation from donors with HIV to recipients with HIV.

Liver transplantation (LT) from donors-with-HIV to recipients-with-HIV (HIV D+/R+) is permitted under the HOPE Act. There are only three international single-case reports of HIV D+/R+ LT, each with limited follow-up. We performed a prospective multicenter pilot study comparing HIV D+/R+ to donors-without-HIV to recipients-with-HIV (HIV D-/R+) LT. We quantified patient survival, graft survival, rejection, serious adverse events (SAEs), human immunodeficiency virus (HIV) breakthrough, infections, and malignancies, using Cox and negative binomial regression with inverse probability of treatment weighting. Between March 2016-July 2019, there were 45 LTs (8 simultaneous liver-kidney) at 9 centers: 24 HIV D+/R+, 21 HIV D-/R+ (10 D- were false-positive). The median follow-up time was 23 months. Median recipient CD4 was 287 cells/µL with 100% on antiretroviral therapy; 56% were hepatitis C virus (HCV)-seropositive, 13% HCV-viremic. Weighted 1-year survival was 83.3% versus 100.0% in D+ versus D- groups (p = .04). There were no differences in one-year graft survival (96.0% vs. 100.0%), rejection (10.8% vs. 18.2%), HIV breakthrough (8% vs. 10%), or SAEs (all p > .05). HIV D+/R+ had more opportunistic infections, infectious hospitalizations, and cancer. In this multicenter pilot study of HIV D+/R+ LT, patient and graft survival were better than historical cohorts, however, a potential increase in infections and cancer merits further investigation.

Association of Inflammatory Biomarkers with Immunosuppression Management and Outcomes in Kidney Transplant Recipients with COVID-19.

BACKGROUND: Kidney transplant recipients with coronavirus disease 2019 (COVID-19) are at increased risk for adverse outcomes, such as acute kidney injury (AKI), intensive care unit (ICU) admission, and death. The association of inflammatory biomarkers with outcomes and the impact of changes in immunosuppression on biomarker levels are unknown. METHODS: We investigated factors associated with a composite of AKI, ICU admission, or death, and whether immunosuppression changes correlated with changes in inflammatory biomarkers and outcomes in kidney transplant recipients with a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction. RESULTS: Of 59 patients, 50% had estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2. Patients who discontinued calcineurin inhibitors (CNIs) had higher peak high-sensitivity C-reactive protein (hs-CRP) than those who maintained the same dose (median, 344; interquartile range [IQR], 145-374 vs median, 41; IQR, 22-116 mg/L, P = .03). Of the patients, 73% were hospitalized, 22% had admissions to the ICU, and 20% died. Of the 56% with AKI, 35% required dialysis. All patients with AKI but without pulmonary manifestations recovered to 10% of baseline creatinine levels. Factors associated with the composite outcome were eGFR <60 mL/min/1.73 m2 (odds ratio [OR], 5.833; 95% confidence interval [CI], 1.880-18.099; P = .002), hs-CRP (OR, 1.011/unit increase; 95% CI, 1.002-1.021; P = .019), white blood cell count (OR, 1.173/unit increase; 95% CI, 1.006-1.368; P = .041), and decreased or discontinued CNI (OR, 4.286; 95% CI, 1.353-13.572; P = .013). eGFR<60 mL/min/1.73 m2 (OR, 11.176; 95% CI, 1.581-79.001; P = .016), and peak hs-CRP (OR, 1.010/unit increase; 95% CI, 1.000-1.020; P = .049) remained associated with the composite in the multivariable model. CONCLUSIONS: Kidney transplant recipients with COVID-19 have high rates of ICU admissions, AKI, and death. Those with eGFR<60 mL/min/1.73 m2 are at highest risk. CNI reduction is associated with higher inflammatory biomarkers, correlating with worse outcomes. More studies are needed to determine if this association should drive clinical management.

Clinical Rationale for a Routine Testing Schedule Using Donor-Derived Cell-Free DNA After Kidney Transplantation.

Kidney transplant recipients require meticulous clinical and laboratory surveillance to monitor allograft health. Conventional biomarkers, including serum creatinine and proteinuria, are lagging indicators of allograft injury, often rising only after significant and potentially irreversible damage has occurred. Immunosuppressive medication levels can be followed, but their utility is largely limited to guiding dosing changes or assessing adherence. Kidney biopsy, the criterion standard for the diagnosis and characterization of injury, is invasive and thus poorly suited for frequent surveillance. Donor-derived cell-free DNA (dd-cfDNA) is a sensitive, noninvasive, leading indicator of allograft injury, which offers the opportunity for expedited intervention and can improve long-term allograft outcomes. This article describes the clinical rationale for a routine testing schedule utilizing dd-cfDNA surveillance at months 1, 2, 3, 4, 6, 9, and 12 during the first year following kidney transplantation and quarterly thereafter. These time points coincide with major immunologic transition points after transplantation and provide clinicians with molecular information to help inform decision making.

Assessing accuracy of estimated dry weight in dialysis patients post transplantation: the kidney knows best.

INTRODUCTION: Estimated dry weight is used to guide fluid removal during outpatient hemodialysis sessions. Errors in estimated dry weight can result in intradialytic hypotension and interdialytic fluid overload. The goal of this study was to assess the accuracy of estimated dry weight by comparing it to the 2-week post-transplant weight in two cohorts of hemodialysis patients. METHODS: This observational, multi-center, retrospective cohort study included maintenance hemodialysis patients who underwent kidney transplantation at two medical centers in Massachusetts. The relationship between estimated dry weight pre-transplant and weight at week 2 post-transplant in patients with good allograft function (serum creatinine ≤ 1.5 mg/dL) was analyzed. Estimated dry weight was considered accurate if it was within ± 2% of the week 2 post-transplant weight. RESULTS: Fifty seven patients with good allograft function were identified: mean age 54 ± 14 years, 32 (58%) from deceased donors, 22 (38.6%) females. 38 were Caucasian (66.7%), 11 Hispanic (19.3%), 3 black (5.3%), and 5 others (8.8%). 2-week mean post transplantation serum creatinine was 1.2 ± 0.2 mg/dL. Mean (SD) estimated dry weight was 71.4 ± 15.9. Before transplantation, only 14 (24.6%) patients were within ± 2% of the 2-week post-transplant weight; 23 (40.3%) were above and 20 (35.1%) were below. CONCLUSIONS: Our point of view, based on the assumption that the weight of patients with good allograft function at 2 weeks post-transplant approaches their accurate dry weight, is that a majority of maintenance hemodialysis patients (75.4%) are hypervolemic or hypovolemic prior to renal transplantation. This highlights the importance of finding novel tools to achieve euvolemia in patients undertaking dialysis. Timely feedback regarding achieved weight 2 weeks post-transplant to treating nephrologists and dialysis centers may be a starting point for assessing accuracy of dry weight.

Long-Term Immunosuppression Management: Opportunities and Uncertainties.

The long-term management of maintenance immunosuppression in kidney transplant recipients remains complex. The vast majority of patients are treated with the calcineurin inhibitor tacrolimus as the primary agent in combination with mycophenolate, with or without corticosteroids. A tacrolimus trough target 5-8 ng/ml seems to be optimal for rejection prophylaxis, but long-term tacrolimus-related side effects and nephrotoxicity support the ongoing evaluation of noncalcineurin inhibitor-based regimens. Current alternatives include belatacept or mammalian target of rapamycin inhibitors. For the former, superior kidney function at 7 years post-transplant compared with cyclosporin generated initial enthusiasm, but utilization has been hampered by high initial rejection rates. Mammalian target of rapamycin inhibitors have yielded mixed results as well, with improved kidney function tempered by higher risk of rejection, proteinuria, and adverse effects leading to higher discontinuation rates. Mammalian target of rapamycin inhibitors may play a role in the secondary prevention of squamous cell skin cancer as conversion from a calcineurin inhibitor to an mammalian target of rapamycin inhibitor resulted in a reduction of new lesion development. Early withdrawal of corticosteroids remains an attractive strategy but also is associated with a higher risk of rejection despite no difference in 5-year patient or graft survival. A major barrier to long-term graft survival is chronic alloimmunity, and regardless of agent used, managing the toxicities of immunosuppression against the risk of chronic antibody-mediated rejection remains a fragile balance.

Comparing Urine and Blood Screening Methods to Detect BK Virus After Renal Transplant.

OBJECTIVES: BK polyomavirus can infect healthy individuals; however, in renal transplant recipients, it can cause nephropathy, which can lead to renal allograftfailure. There are currently no effective antiviral agents against BK polyomavirus. Surveillance after kidney transplant for BK polyomavirus is the only means to prevent allograft failure. Transplant centers routinely screen for BK polyomavirus in either urine or blood. If BK polyomavirus replication occurs, itis usually detected first in urine, which is followed by detection in blood in a subset of cases. Screening for BK polyomavirus in urine has the potential for earlier detection of viralreactivation.However, not all patients with BK polyomavirus in urine will progress to BK viremia. Therefore, adding urine screening could increase the cost oftests without a clear clinical benefit. MATERIALS AND METHODS: We conducted an analysis of BK polyomavirus screening methods at 2 different centers and compared their clinical outcomes and efficiency of testing. RESULTS: We analyzed 209 patientswith BK polyomavirus reactivation after kidney transplant at 2 different institutions from 2008 to 2018. BK polyomavirus reactivation in blood was detected earlierifthe patient was screened by urine screening protocol. However, measurable clinical outcomes were similarin all groups with different screening methods. CONCLUSIONS: Although screening for BK polyomavirus in urine did detect viralreactivation earlier,there were no differences in graft or clinical outcomes when either the urine or blood screening method was used.

Optimization of de novo belatacept-based immunosuppression administered to renal transplant recipients.

Kidney transplant recipients administered belatacept-based maintenance immunosuppression present with a more favorable metabolic profile, reduced incidence of de novo donor-specific antibodies (DSAs), and improved renal function and long-term patient/graft survival relative to individuals receiving calcineurin inhibitor (CNI)-based immunosuppression. However, the rates and severity of acute rejection (AR) are greater with the approved belatacept-based regimen than with CNI-based immunosuppression. Although these early co-stimulation blockade-resistant rejections are typically steroid sensitive, the higher rate of cellular AR has led many transplant centers to adopt immunosuppressive regimens that differ from the approved label. This article summarizes the available data on these alternative de novo belatacept-based maintenance regimens. Steroid-sparing, belatacept-based immunosuppression (following T cell-depleting induction therapy) has been shown to yield AR rates comparable to those seen with CNI-based regimens. Concomitant treatment with belatacept plus a mammalian target of rapamycin inhibitor (mTORi; sirolimus or everolimus) has yielded AR rates ranging from 0 to 4%. Because the optimal induction agent and number of induction doses; blood levels of mTORi; and dose, duration, and use of corticosteroids have yet to be determined, larger prospective clinical trials are needed to establish the optimal alternative belatacept-based regimen for minimizing early cellular AR occurrence.

Short Bowel Syndrome and Kidney Transplantation: Challenges, Outcomes, and the Use of Teduglutide.

Among patients with short bowel syndrome who commonly have kidney disease, kidney transplantation remains challenging. We describe the clinicopathologic course of a 59-year old man with short bowel syndrome secondary to Crohn's disease who underwent a deceased donor kidney transplant that was complicated by recurrent acute kidney allograft injury due to volume depletion from diarrhea, ultimately requiring the placement of permanent intravenous access for daily volume expansion at home resulting in the recovery of allograft function. Teduglutide treatment at 1.8 years post-transplant led to a dramatic decrease in diarrhea. A literature review of similar cases yielded 18 patients who underwent 19 kidney transplants. Despite high rates of complications, at the time of last follow-up (median 2.1 years [0.04-7]), 94% of the patients were still alive and 89% had functioning allografts, with a median eGFR of 37.5 [14-122] ml/min/1.73m2. In conclusion, despite high rates of complications, kidney transplantation in patients with short bowel syndrome is associated with acceptable short- and midterm outcomes. Further, we report for the first time the effects of the glucagon-like peptide-2 analogue teduglutide for short bowel syndrome in a kidney transplant recipient.

Preemptive Treatment With Elbasvir and Grazoprevir for Hepatitis C-Viremic Donor to Uninfected Recipient Kidney Transplantation.

INTRODUCTION: Long wait times for kidney transplants have prompted investigation into strategies to decrease the discarding of potentially viable organs. Recent reports suggest that kidneys from hepatitis C virus (HCV)-infected donors may be transplanted into HCV-naive donors followed by direct-acting antiviral therapy. METHODS: This was a pilot clinical trial to transplant kidneys from HCV-infected donors into HCV-naive recipients with preemptive use of elbasvir and grazoprevir for 12 weeks. The primary outcome was sustained virologic response 12 weeks after completion of therapy. Secondary outcomes were safety, quality of life, and early viral kinetics. RESULTS: A total of 33 patients were screened, and 8 underwent kidney transplantation from a HCV-viremic donors from August 2017 to March 2019. The median donor kidney donor profile index was 31% (range, 29%-65%), and patients who underwent transplantation waited a median of 6.5 months (range, 1-19 months). None had detectable HCV viremia beyond 2 weeks post-transplantation, and all achieved sustained virologic response 12 weeks after therapy (SVR12). There were no study-related severe adverse events. One patient experienced early graft loss due to venous thrombosis, whereas the remaining 7 patients had excellent allograft function at 6 months. CONCLUSION: Preemptive elbasvir and grazoprevir eliminated HCV infection in HCV-naive patients who received a kidney transplant from an HCV-infected donor.

Association between Human Leukocyte Antigen Type and Keratinocyte Carcinoma Risk in Renal Transplant Recipients.

Keratinocyte carcinoma (KC), defined as squamous cell carcinoma and basal cell carcinoma, is the most common malignancy among white, non-Hispanic renal transplant recipients. Although recent genome-wide association studies reported that class II HLA is associated with KC risk, epidemiologic data on HLA type and KC risk in renal transplant recipients is limited. Using an institutional cohort of white, non-Hispanic renal transplant recipients transplanted between 1993 and 2017, we examined the association between pretransplant molecular HLA types and KC risk. Posttransplant KCs were captured using the International Classification of Diseases codes and validated using pathology reports. Cox proportional hazards regression models were used to estimate hazard ratios of incident KC, squamous cell carcinoma, and basal cell carcinoma, adjusting for age, male sex, history of KC, Charlson comorbidity index, HLA mismatch, transplant type, year of transplant, and the type of immunosuppression. Among 617 subjects (mean age 53 years, 67% male), 10% developed posttransplant KC. Multivariable Cox regression analyses showed HLA-DRB1∗13 was associated with KC risk (hazard ratio, 1.84; 95% confidence interval, 1.00-3.38) and squamous cell carcinoma risk (hazard ratio, 2.24; 95% confidence interval, 1.12-4.49), whereas HLA-DRB1∗14 (hazard ratio, 2.81; 95% confidence interval, 1.14-6.91) was associated with basal cell carcinoma risk. Our findings suggest that a subset of renal transplant recipients with specific HLA polymorphisms may be at increased KC risk.

Process of selecting and educating HCV-uninfected kidney waiting-list candidates for HCV-infected kidney transplantation.

Long waiting times for kidney transplant (KT) and the high risk of mortality on dialysis have prompted investigation into strategies to utilize hepatitis C virus (HCV)-infected organs to decrease discard rates of potentially viable kidneys. Due the opioid epidemic, the number of HCV-infected donors has increased significantly. With the development of direct-acting antiviral therapies for HCV infection, now more than 95% of patients who received treatment are cured. Experimental trials have used direct-acting antiviral therapy to treat HCV infection in HCV-uninfected transplant recipients of kidneys from HCV-viremic donors. To date, HCV has been eradicated in all cases. Though these strategies will potentially increase the donor pool of available kidneys, shorten waitlist times, and ultimately decrease mortality in patients waiting for KT, identifying the ideal candidates and educating them about a protocol to utilize direct-acting antiviral therapy to cure HCV after it is transmitted is essential. We present our approach to patient selection and education for a clinical trial in transplantation of HCV viremic kidneys into uninfected recipients.

A prospective multicenter observational study of cell-mediated immunity as a predictor for cytomegalovirus infection in kidney transplant recipients.

T cell immunity is essential for the control of cytomegalovirus (CMV) infection after transplantation. We evaluated a CMV-specific peptide-based enzyme-linked immunosorbent spot (ELISPOT) assay to determine whether assay results could predict subsequent CMV events. Adult kidney transplant recipients at 43 centers underwent ELISPOT testing to enumerate interferon gamma (IFN-γ) binding spot-forming units (sfu) after stimulation of cells with an overlapping peptide pool of CMV phosphoprotein 65 (pp65) and immediate early-1 (IE-1) protein at the end of antiviral prophylaxis (EOP) and various time points thereafter. The primary outcome was a CMV event in the first posttransplant year. In 583 kidney transplant recipients (260 seropositive donor [D+]/seronegative recipient [R-] and 277 R+), CMV events occurred in 44 of 368 eligible patients (11.8%) at a median of 227 days (range 92-360) posttransplant. A cutoff value of >40 sfu/2.5 × 105  cells for either IE-1 or pp65 was derived as a threshold for positivity, with a negative predictive value of >97% for CMV events. CMV events were significantly lower in assay positive vs assay negative patients (3.0% vs 19.5%, P < .0001 for pp65). Time to CMV event post-EOP was significantly greater in those with sfu >40 at EOP (P < .0001). In this large, multicenter trial of kidney transplant recipients, we show that an assessment of CMV-specific immunity using a novel ELISPOT assay is able to predict protection from CMV infection.