Longitudinal Analysis of the Human B Cell Response to Ebola Virus Infection.

Ebola virus (EBOV) remains a public health threat. We performed a longitudinal study of B cell responses to EBOV in four survivors of the 2014 West African outbreak. Infection induced lasting EBOV-specific immunoglobulin G (IgG) antibodies, but their subclass composition changed over time, with IgG1 persisting, IgG3 rapidly declining, and IgG4 appearing late. Striking changes occurred in the immunoglobulin repertoire, with massive recruitment of naive B cells that subsequently underwent hypermutation. We characterized a large panel of EBOV glycoprotein-specific monoclonal antibodies (mAbs). Only a small subset of mAbs that bound glycoprotein by ELISA recognized cell-surface glycoprotein. However, this subset contained all neutralizing mAbs. Several mAbs protected against EBOV disease in animals, including one mAb that targeted an epitope under evolutionary selection during the 2014 outbreak. Convergent antibody evolution was seen across multiple donors, particularly among VH3-13 neutralizing antibodies specific for the GP1 core. Our study provides a benchmark for assessing EBOV vaccine-induced immunity.

Metabolic Phenotypes of Response to Vaccination in Humans.

Herpes zoster (shingles) causes significant morbidity in immune compromised hosts and older adults. Whereas a vaccine is available for prevention of shingles, its efficacy declines with age. To help to understand the mechanisms driving vaccinal responses, we constructed a multiscale, multifactorial response network (MMRN) of immunity in healthy young and older adults immunized with the live attenuated shingles vaccine Zostavax. Vaccination induces robust antigen-specific antibody, plasmablasts, and CD4+ T cells yet limited CD8+ T cell and antiviral responses. The MMRN reveals striking associations between orthogonal datasets, such as transcriptomic and metabolomics signatures, cell populations, and cytokine levels, and identifies immune and metabolic correlates of vaccine immunity. Networks associated with inositol phosphate, glycerophospholipids, and sterol metabolism are tightly coupled with immunity. Critically, the sterol regulatory binding protein 1 and its targets are key integrators of antibody and T follicular cell responses. Our approach is broadly applicable to study human immunity and can help to identify predictors of efficacy as well as mechanisms controlling immunity to vaccination.

Defining antigen-specific plasmablast and memory B cell subsets in human blood after viral infection or vaccination.

Antigen-specific B cells bifurcate into antibody-secreting cells (ASCs) and memory B cells (MBCs) after infection or vaccination. ASCs (plasmablasts) have been extensively studied in humans, but less is known about B cells that become activated but do not differentiate into plasmablasts. Here we have defined the phenotype and transcriptional program of a subset of antigen-specific B cells, which we have called 'activated B cells' (ABCs), that were distinct from ASCs and were committed to the MBC lineage. We detected ABCs in humans after infection with Ebola virus or influenza virus and also after vaccination. By simultaneously analyzing antigen-specific ASCs and ABCs in human blood after vaccination against influenza virus, we investigated the clonal overlap and extent of somatic hypermutation (SHM) in the ASC (effector) and ABC (memory) lineages. Longitudinal tracking of vaccination-induced hemagglutinin (HA)-specific clones revealed no overall increase in SHM over time, which suggested that repeated annual immunization might have limitations in enhancing the quality of influenza-virus-specific antibody.

Baricitinib plus Remdesivir for Hospitalized Adults with Covid-19.

BACKGROUND: Severe coronavirus disease 2019 (Covid-19) is associated with dysregulated inflammation. The effects of combination treatment with baricitinib, a Janus kinase inhibitor, plus remdesivir are not known. METHODS: We conducted a double-blind, randomized, placebo-controlled trial evaluating baricitinib plus remdesivir in hospitalized adults with Covid-19. All the patients received remdesivir (≤10 days) and either baricitinib (≤14 days) or placebo (control). The primary outcome was the time to recovery. The key secondary outcome was clinical status at day 15. RESULTS: A total of 1033 patients underwent randomization (with 515 assigned to combination treatment and 518 to control). Patients receiving baricitinib had a median time to recovery of 7 days (95% confidence interval [CI], 6 to 8), as compared with 8 days (95% CI, 7 to 9) with control (rate ratio for recovery, 1.16; 95% CI, 1.01 to 1.32; P = 0.03), and a 30% higher odds of improvement in clinical status at day 15 (odds ratio, 1.3; 95% CI, 1.0 to 1.6). Patients receiving high-flow oxygen or noninvasive ventilation at enrollment had a time to recovery of 10 days with combination treatment and 18 days with control (rate ratio for recovery, 1.51; 95% CI, 1.10 to 2.08). The 28-day mortality was 5.1% in the combination group and 7.8% in the control group (hazard ratio for death, 0.65; 95% CI, 0.39 to 1.09). Serious adverse events were less frequent in the combination group than in the control group (16.0% vs. 21.0%; difference, -5.0 percentage points; 95% CI, -9.8 to -0.3; P = 0.03), as were new infections (5.9% vs. 11.2%; difference, -5.3 percentage points; 95% CI, -8.7 to -1.9; P = 0.003). CONCLUSIONS: Baricitinib plus remdesivir was superior to remdesivir alone in reducing recovery time and accelerating improvement in clinical status among patients with Covid-19, notably among those receiving high-flow oxygen or noninvasive ventilation. The combination was associated with fewer serious adverse events. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT04401579.).

Systems Analysis of Immunity to Influenza Vaccination across Multiple Years and in Diverse Populations Reveals Shared Molecular Signatures.

Systems approaches have been used to describe molecular signatures driving immunity to influenza vaccination in humans. Whether such signatures are similar across multiple seasons and in diverse populations is unknown. We applied systems approaches to study immune responses in young, elderly, and diabetic subjects vaccinated with the seasonal influenza vaccine across five consecutive seasons. Signatures of innate immunity and plasmablasts correlated with and predicted influenza antibody titers at 1 month after vaccination with >80% accuracy across multiple seasons but were not associated with the longevity of the response. Baseline signatures of lymphocyte and monocyte inflammation were positively and negatively correlated, respectively, with antibody responses at 1 month. Finally, integrative analysis of microRNAs and transcriptomic profiling revealed potential regulators of vaccine immunity. These results identify shared vaccine-induced signatures across multiple seasons and in diverse populations and might help guide the development of next-generation vaccines that provide persistent immunity against influenza.

Remdesivir for the Treatment of Covid-19 - Final Report.

BACKGROUND: Although several therapeutic agents have been evaluated for the treatment of coronavirus disease 2019 (Covid-19), no antiviral agents have yet been shown to be efficacious. METHODS: We conducted a double-blind, randomized, placebo-controlled trial of intravenous remdesivir in adults who were hospitalized with Covid-19 and had evidence of lower respiratory tract infection. Patients were randomly assigned to receive either remdesivir (200 mg loading dose on day 1, followed by 100 mg daily for up to 9 additional days) or placebo for up to 10 days. The primary outcome was the time to recovery, defined by either discharge from the hospital or hospitalization for infection-control purposes only. RESULTS: A total of 1062 patients underwent randomization (with 541 assigned to remdesivir and 521 to placebo). Those who received remdesivir had a median recovery time of 10 days (95% confidence interval [CI], 9 to 11), as compared with 15 days (95% CI, 13 to 18) among those who received placebo (rate ratio for recovery, 1.29; 95% CI, 1.12 to 1.49; P<0.001, by a log-rank test). In an analysis that used a proportional-odds model with an eight-category ordinal scale, the patients who received remdesivir were found to be more likely than those who received placebo to have clinical improvement at day 15 (odds ratio, 1.5; 95% CI, 1.2 to 1.9, after adjustment for actual disease severity). The Kaplan-Meier estimates of mortality were 6.7% with remdesivir and 11.9% with placebo by day 15 and 11.4% with remdesivir and 15.2% with placebo by day 29 (hazard ratio, 0.73; 95% CI, 0.52 to 1.03). Serious adverse events were reported in 131 of the 532 patients who received remdesivir (24.6%) and in 163 of the 516 patients who received placebo (31.6%). CONCLUSIONS: Our data show that remdesivir was superior to placebo in shortening the time to recovery in adults who were hospitalized with Covid-19 and had evidence of lower respiratory tract infection. (Funded by the National Institute of Allergy and Infectious Diseases and others; ACTT-1 ClinicalTrials.gov number, NCT04280705.).

Systems biology of vaccination for seasonal influenza in humans.

Here we have used a systems biology approach to study innate and adaptive responses to vaccination against influenza in humans during three consecutive influenza seasons. We studied healthy adults vaccinated with trivalent inactivated influenza vaccine (TIV) or live attenuated influenza vaccine (LAIV). TIV induced higher antibody titers and more plasmablasts than LAIV did. In subjects vaccinated with TIV, early molecular signatures correlated with and could be used to accurately predict later antibody titers in two independent trials. Notably, expression of the kinase CaMKIV at day 3 was inversely correlated with later antibody titers. Vaccination of CaMKIV-deficient mice with TIV induced enhanced antigen-specific antibody titers, which demonstrated an unappreciated role for CaMKIV in the regulation of antibody responses. Thus, systems approaches can be used to predict immunogenicity and provide new mechanistic insights about vaccines.

Temporal Improvements in COVID-19 Outcomes for Hospitalized Adults: A Post Hoc Observational Study of Remdesivir Group Participants in the Adaptive COVID-19 Treatment Trial.

BACKGROUND: The COVID-19 standard of care (SOC) evolved rapidly during 2020 and 2021, but its cumulative effect over time is unclear. OBJECTIVE: To evaluate whether recovery and mortality improved as SOC evolved, using data from ACTT (Adaptive COVID-19 Treatment Trial). DESIGN: ACTT is a series of phase 3, randomized, double-blind, placebo-controlled trials that evaluated COVID-19 therapeutics from February 2020 through May 2021. ACTT-1 compared remdesivir plus SOC to placebo plus SOC, and in ACTT-2 and ACTT-3, remdesivir plus SOC was the control group. This post hoc analysis compared recovery and mortality between these comparable sequential cohorts of patients who received remdesivir plus SOC, adjusting for baseline characteristics with propensity score weighting. The analysis was repeated for participants in ACTT-3 and ACTT-4 who received remdesivir plus dexamethasone plus SOC. Trends in SOC that could explain outcome improvements were analyzed. (ClinicalTrials.gov: NCT04280705 [ACTT-1], NCT04401579 [ACTT-2], NCT04492475 [ACTT-3], and NCT04640168 [ACTT-4]). SETTING: 94 hospitals in 10 countries (86% U.S. participants). PARTICIPANTS: Adults hospitalized with COVID-19. INTERVENTION: SOC. MEASUREMENTS: 28-day mortality and recovery. RESULTS: Although outcomes were better in ACTT-2 than in ACTT-1, adjusted hazard ratios (HRs) were close to 1 (HR for recovery, 1.04 [95% CI, 0.92 to 1.17]; HR for mortality, 0.90 [CI, 0.56 to 1.40]). Comparable patients were less likely to be intubated in ACTT-2 than in ACTT-1 (odds ratio, 0.75 [CI, 0.53 to 0.97]), and hydroxychloroquine use decreased. Outcomes improved from ACTT-2 to ACTT-3 (HR for recovery, 1.43 [CI, 1.24 to 1.64]; HR for mortality, 0.45 [CI, 0.21 to 0.97]). Potential explanatory factors (SOC trends, case surges, and variant trends) were similar between ACTT-2 and ACTT-3, except for increased dexamethasone use (11% to 77%). Outcomes were similar in ACTT-3 and ACTT-4. Antibiotic use decreased gradually across all stages. LIMITATION: Unmeasured confounding. CONCLUSION: Changes in patient composition explained improved outcomes from ACTT-1 to ACTT-2 but not from ACTT-2 to ACTT-3, suggesting improved SOC. These results support excluding nonconcurrent controls from analysis of platform trials in rapidly changing therapeutic areas. PRIMARY FUNDING SOURCE: National Institute of Allergy and Infectious Diseases.

Racial and Ethnic Differences and Clinical Outcomes of Patients With Coronavirus Disease 2019 (COVID-19) Presenting to the Emergency Department.

BACKGROUND: Since the introduction of remdesivir and dexamethasone for severe COVID-19 treatment, few large multi-hospital-system US studies have described clinical characteristics and outcomes of minority COVID-19 patients who present to the emergency department (ED). METHODS: This cohort study from the Cerner Real World Database (87 US health systems) from 1 December 2019 to 30 September 2020 included PCR-confirmed COVID-19 patients who self-identified as non-Hispanic Black (Black), Hispanic White (Hispanic), or non-Hispanic White (White). The main outcome was hospitalization among ED patients. Secondary outcomes included mechanical ventilation, intensive care unit care, and in-hospital mortality. Descriptive statistics and Poisson regression compared sociodemographics, comorbidities, receipt of remdesivir or dexamethasone, and outcomes by racial/ethnic groups and geographic region. RESULTS: 94 683 COVID-19 patients presented to the ED. Blacks comprised 26.7% and Hispanics 33.6%. Nearly half (45.1%) of ED patients presented to hospitals in the South. 31.4% (n = 29 687) were hospitalized. Lower proportions of Blacks were prescribed dexamethasone (29.4%; n = 7426) compared with Hispanics (40.9%; n = 13 021) and Whites (37.5%; n = 14 088). Hospitalization risks, compared with Whites, were similar in Blacks (RR: .94; 95% CI: .82-1.08; P = .4) and Hispanics (.99; .81-1.21; P = .91), but risk of in-hospital mortality was higher in Blacks (1.18; 1.06-1.31; P = .002) and Hispanics (1.28; 1.13-1.44; P < .001). CONCLUSIONS: Minority patients were overrepresented among COVID-19 ED patients, and while their risks of hospitalization were similar to Whites, in-hospital mortality risk was higher. Interventions targeting upstream social determinants of health are needed to reduce racial/ethnic disparities in COVID-19.

Deconstructing the Treatment Effect of Remdesivir in the Adaptive Coronavirus Disease 2019 (COVID-19) Treatment Trial-1: Implications for Critical Care Resource Utilization.

BACKGROUND: The Adaptive Coronavirus Disease 2019 (COVID-19) Treatment Trial-1 (ACTT-1) found that remdesivir therapy hastened recovery in patients hospitalized with COVID-19, but the pathway for this improvement was not explored. We investigated how the dynamics of clinical progression changed along 4 pathways: recovery, improvement in respiratory therapy requirement, deterioration in respiratory therapy requirement, and death. METHODS: We analyzed trajectories of daily ordinal severity scores reflecting oxygen requirements of 1051 patients hospitalized with COVID-19 who participated in ACTT-1. We developed competing risks models that estimate the effect of remdesivir therapy on cumulative incidence of clinical improvement and deterioration, and multistate models that utilize the entirety of each patient's clinical course to characterize the effect of remdesivir on progression along the 4 pathways above. RESULTS: Based on a competing risks analysis, remdesivir reduced clinical deterioration (hazard ratio [HR], 0.73; 95% confidence interval [CI]: .59-.91) and increased clinical improvement (HR, 1.22; 95% CI: 1.08, 1.39) relative to baseline. Our multistate models indicate that remdesivir inhibits worsening to ordinal scores of greater clinical severity among patients on room air or low-flow oxygen (HR, 0.74; 95% CI: .57-.94) and among patients receiving mechanical ventilation or high-flow oxygen/noninvasive positive-pressure ventilation (HR, 0.73; 95% CI: .53-1.00) at baseline. We also find that remdesivir reduces expected intensive care respiratory therapy utilization among patients not mechanically ventilated at baseline. CONCLUSIONS: Remdesivir speeds time to recovery by preventing worsening to clinical states that would extend the course of hospitalization and increase intensive respiratory support, thereby reducing the overall demand for hospital care.

National Landscape of Human Immunodeficiency Virus-Positive Deceased Organ Donors in the United States.

BACKGROUND: Organ transplantation from donors with human immunodeficiency virus (HIV) to recipients with HIV (HIV D+/R+) presents risks of donor-derived infections. Understanding clinical, immunologic, and virologic characteristics of HIV-positive donors is critical for safety. METHODS: We performed a prospective study of donors with HIV-positive and HIV false-positive (FP) test results within the HIV Organ Policy Equity (HOPE) Act in Action studies of HIV D+/R+ transplantation (ClinicalTrials.gov NCT02602262, NCT03500315, and NCT03734393). We compared clinical characteristics in HIV-positive versus FP donors. We measured CD4 T cells, HIV viral load (VL), drug resistance mutations (DRMs), coreceptor tropism, and serum antiretroviral therapy (ART) detection, using mass spectrometry in HIV-positive donors. RESULTS: Between March 2016 and March 2020, 92 donors (58 HIV positive, 34 FP), representing 98.9% of all US HOPE donors during this period, donated 177 organs (131 kidneys and 46 livers). Each year the number of donors increased. The prevalence of hepatitis B (16% vs 0%), syphilis (16% vs 0%), and cytomegalovirus (CMV; 91% vs 58%) was higher in HIV-positive versus FP donors; the prevalences of hepatitis C viremia were similar (2% vs 6%). Most HIV-positive donors (71%) had a known HIV diagnosis, of whom 90% were prescribed ART and 68% had a VL <400 copies/mL. The median CD4 T-cell count (interquartile range) was 194/µL (77-331/µL), and the median CD4 T-cell percentage was 27.0% (16.8%-36.1%). Major HIV DRMs were detected in 42%, including nonnucleoside reverse-transcriptase inhibitors (33%), integrase strand transfer inhibitors (4%), and multiclass (13%). Serum ART was detected in 46% and matched ART by history. CONCLUSION: The use of HIV-positive donor organs is increasing. HIV DRMs are common, yet resistance that would compromise integrase strand transfer inhibitor-based regimens is rare, which is reassuring regarding safety.

Fecal Microbiota Transplantation Donor Screening Updates and Research Gaps for Solid Organ Transplant Recipients.

In this review, we discuss stool donor screening considerations to mitigate potential risks of pathogen transmission through fecal microbiota transplant (FMT) in solid organ transplant (SOT) recipients. SOT recipients have a higher risk for Clostridioides difficile infection (CDI) and are more likely to have severe CDI. FMT has been shown to be a valuable tool in the treatment of recurrent CDI (RCDI); however, guidelines for screening for opportunistic infections transmitted through FMT are underdeveloped. We review reported adverse effects of FMT as they pertain to an immunocompromised population and discuss the current understanding and recommendations for screening found in the literature while noting gaps in research. We conclude that while FMT is being performed in the SOT population, typically with positive results, there remain many unanswered questions which may have major safety implications and warrant further study.

Severe Monkeypox in Hospitalized Patients - United States, August 10-October 10, 2022.

As of October 21, 2022, a total of 27,884 monkeypox cases (confirmed and probable) have been reported in the United States.§ Gay, bisexual, and other men who have sex with men have constituted a majority of cases, and persons with HIV infection and those from racial and ethnic minority groups have been disproportionately affected (1,2). During previous monkeypox outbreaks, severe manifestations of disease and poor outcomes have been reported among persons with HIV infection, particularly those with AIDS (3-5). This report summarizes findings from CDC clinical consultations provided for 57 patients aged ≥18 years who were hospitalized with severe manifestations of monkeypox¶ during August 10-October 10, 2022, and highlights three clinically representative cases. Overall, 47 (82%) patients had HIV infection, four (9%) of whom were receiving antiretroviral therapy (ART) before monkeypox diagnosis. Most patients were male (95%) and 68% were non-Hispanic Black (Black). Overall, 17 (30%) patients received intensive care unit (ICU)-level care, and 12 (21%) have died. As of this report, monkeypox was a cause of death or contributing factor in five of these deaths; six deaths remain under investigation to determine whether monkeypox was a causal or contributing factor; and in one death, monkeypox was not a cause or contributing factor.** Health care providers and public health professionals should be aware that severe morbidity and mortality associated with monkeypox have been observed during the current outbreak in the United States (6,7), particularly among highly immunocompromised persons. Providers should test all sexually active patients with suspected monkeypox for HIV at the time of monkeypox testing unless a patient is already known to have HIV infection. Providers should consider early commencement and extended duration of monkeypox-directed therapy†† in highly immunocompromised patients with suspected or laboratory-diagnosed monkeypox.§§ Engaging all persons with HIV in sustained care remains a critical public health priority.

Early steps to kidney transplantation among persons with HIV and end-stage renal disease in ESRD network 6.

INTRODUCTION: End-stage renal disease is a significant cause of morbidity and mortality in persons with HIV (PWH). Limited data exist on access to kidney transplantation for this population. METHODS: A dataset inclusive of incident dialysis patients between 2012 and 2016 with follow-up through December 2017 that identifies PWH and the general dialysis population of Network 6 (Georgia, North Carolina, South Carolina) was created through merging the United States Renal Data System with the southeastern early transplant access registry. Early steps to kidney transplantation and patient and dialysis facility-level characteristics that serve as barriers to transplantation were described. RESULTS: Twenty-three thousand four hundred fourteen patients were identified; 469 were PWH. Compared to non-HIV individuals, PWH were younger (49 vs. 58 years, p < 0.001), predominantly Black (87% vs. 56% p < 0.001) and male (72% vs. 56% p < 0.001). PWH were less likely to be referred to kidney transplant within 1 year of starting dialysis (36% vs. 41% p < 0.001) and waitlisted within 1 year of evaluation-start (14% vs. 30%, p = 0.05). PWH (vs. non-PWH) waited longer for referral, evaluation-start, and waitlisting and in multivariable analysis; HIV positivity was associated with a lower probability of referral (hazard ratios [HR]: 0.70; 95% confidence intervals [CIs]: 0.62-0.80), evaluation (HR 0.66; 95% CI: 0.55-0.80), and waitlisting (HR 0.29; 95% CI: 0.20-0.41). CONCLUSIONS: Targeted interventions are needed to improve access to kidney transplants, particularly in waitlisting, for PWH.

Impact of belatacept and tacrolimus on cytomegalovirus viral load control and relapse in moderate and high-risk cytomegalovirus serostatus kidney transplant recipients.

BACKGROUND: Belatacept improves long-term graft survival, but control of some primary viral infections may be impaired. We evaluated the impact of belatacept and tacrolimus on cytomegalovirus (CMV) viral control, remission and relapse in CMV high-risk and moderate-risk recipients. METHODS: Using a multistate Markov model, we evaluated viral load state transitions of 173 kidney transplant recipients with at least one episode of viremia within 1 year after transplant: state 1, undetectable/low viral load; state 2, moderate viremia; and state 3, severe viremia. RESULTS: Among high-risk recipients, belatacept-treated recipients exhibited a significantly higher probability of entering moderate viremia (.36; 95% CI = .31, .41) than tacrolimus-treated recipients (.20; 95% CI = .13, .29). The expected number of days in viremic states differed. High-risk belatacept-treated recipients persisted in moderate viremia for significantly longer (128 days, 95% CI = 110, 146) than did tacrolimus-treated recipients (70.0 days, 95% CI = 45.2, 100) and showed a trend of shorter duration in low/undetectable viral load state (172 days, 95% CI = 148, 195) than did tacrolimus-treated recipients (239 days, 95% CI = 195, 277). Moderate-risk recipients showed better viral load control and with no differences by immunosuppression. CONCLUSION: High-risk belatacept-treated recipients showed defects in sustaining viral control relative to tacrolimus-treated recipients. Avoidance of initial use belatacept in high-risk recipients or development of modified management protocols should be considered.

CMV high-risk status and posttransplant outcomes in kidney transplant recipients treated with belatacept.

INTRODUCTION: Cytomegalovirus (CMV) remains associated with poor outcomes after kidney transplantation (kTx). The impact of belatacept on CMV infection remains understudied. In this study, we assessed the impact of belatacept on patient and graft survivals. METHODS: CMV seronegative kTx recipients were included. Patient and graft survival were studied using Kaplan-Meier method, log-rank test. Cox models were used to compare outcomes by CMV risk and immunosuppressive regimen. Incidence and persistence of CMV viremia under belatacept vs tacrolimus were compared. RESULTS: Among 308 CMV seronegative recipients, 168 CMV high-risk and 203 belatacept-treated patients were included. High-risk CMV status was associated with lower patient survival and graft survival. Among the CMV high-risk group, patients treated with belatacept presented a higher incidence of CMV viremia, a higher rate of first-line treatment failure and a longer time to virus clearance. They had a nonsignificant trend toward a lower graft survival. CONCLUSION: Belatacept-based maintenance immunosuppression is associated with an increased risk of CMV primary-infection and a prolonged course of viral replication in CMV high-risk patients. Further studies are needed to confirm the nonsignificant trend towards a lower graft survival in CMV high-risk patients treated with belatacept and whether it is explained by the higher risk of CMV reactivation and infection.

TIGIT regulates apoptosis of risky memory T cell subsets implicated in belatacept-resistant rejection.

Belatacept confers increased patient and graft survival in renal transplant recipients relative to calcineurin inhibitors, but is associated with an increased rate of acute rejection. Recent immunophenotypic studies comparing pretransplant T cell phenotypes of patients who reject versus those who remain stable on belatacept identified three potential "risky" memory T cell subsets that potentially underlie belatacept-resistant rejection: CD4+ CD28+ TEM , CD8+ CD28null , and CD4+ CD57+ PD1- subsets. Here, we compared key phenotypic and functional aspects of these human memory T cell subsets, with the goal of identifying additional potential targets to modulate them. Results demonstrate that TIGIT, an increasingly well-appreciated immune checkpoint receptor, was expressed on all three risky memory T cell subsets in vitro and in vivo in the presence of belatacept. Coculture of human memory CD4+ and CD8+ T cells with an agonistic anti-TIGIT mAb significantly increased apoptotic cell death of all three risky memory T cell subsets. Mechanistically, TIGIT-mediated apoptosis of risky memory T cells was dependent on FOXP3+ Treg, suggesting that agonism of the TIGIT pathway increases FOXP3+ Treg suppression of human memory T cell populations. Overall, these data suggest that TIGIT agonism could represent a new therapeutic target to inhibit belatacept-resistant rejection during transplantation.

Cryptococcus transmission through solid organ transplantation in the United States: A report from the Ad Hoc Disease Transmission Advisory Committee.

Cryptococcus species can cause serious life-threatening infection in solid organ transplant recipients by reactivation of prior infection, posttransplant de novo infection, or donor transmission from the transplanted organ. Although previously reported in the literature, the extent of donor-derived cryptococcosis in the United States has not been documented. We analyzed potential donor-derived Cryptococcus transmission events reported to the Organ Procurement and Transplantation Network (OPTN) for investigation by the Ad Hoc Disease Transmission Advisory Committee (DTAC). All reports between 2009 and 2019 in which transmission to recipients was designated proven or probable, or determined to be averted due to implementation of prophylaxis (intervention without disease transmission-"IWDT") were included. During 2009-2019, 58 reports of potential donor-derived cryptococcosis were submitted to DTAC. Among these reports, 12 donors were determined to have resulted in proven or probable transmission to 23/34 (67.6%) recipients. Most of these donors (10/12 [83%]) exhibited central nervous system-related symptoms prior to death and 5/23 (22%) infected recipients died. For 11 different donors, prophylaxis, most often with fluconazole, was administered to 23/35 (65.7%) recipients. Clinicians should maintain awareness of donor-derived cryptococcosis and consider prompt prophylaxis or treatment followed by reporting to OPTN for further investigation.

Clinical characteristics and outcomes of toxoplasmosis among transplant recipients at two US academic medical centers.

Toxoplasma gondii can cause severe opportunistic infection in immunocompromised individuals, but diagnosis is often delayed. We conducted a retrospective review of solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients with toxoplasmosis between 2002 and 2018 at two large US academic transplant centers. Patients were identified by ICD-9 or ICD-10 toxoplasmosis codes, positive Toxoplasma polymerase chain reaction test result, or pathologic diagnosis. Data were collected regarding transplant type, time from transplant to toxoplasmosis diagnosis, clinical and radiographic features, and mortality at 30 and 90 days. Twenty patients were identified: 10 HSCT recipients (80% allogeneic HSCT) and 10 SOT recipients (60% deceased donor renal transplants). Rejection among SOT recipients (70%) and graft-versus-host disease (GVHD) prophylaxis among HSCT recipients (50%) were frequent. Median time from transplant to toxoplasmosis diagnosis was longer for SOT than HSCT (1385 vs. 5 days, P-value .002). Clinical manifestations most commonly were encephalitis (65%), respiratory failure (40%), renal failure (40%), and distributive shock (40%). Cohort 30-day mortality was 45%, and 90-day mortality was 55%. Diagnosis was postmortem in 25% of the cohort. Further evaluation of toxoplasmosis screening is needed for noncardiac SOT recipients, HSCT recipients with GVHD, and periods of increased net immunosuppression.

Adenovirus causing hepatic abscess formation and unexplained fever in adult liver transplant recipients.

Adenovirus infection is commonly associated with self-limited respiratory and gastrointestinal illnesses. However, infection in immunocompromised individuals, such as transplant recipients, can cause severe life-threatening illness including pneumonitis, hemorrhagic cystitis, nephritis, hepatitis, and enterocolitis. In orthotopic liver transplant recipients, adenovirus viremia can cause hepatitis leading to marked transaminitis, allograft loss, and death. Although hepatic abscesses mediated by adenovirus have been described in other immunosuppressed patient populations, it has very rarely been described in liver transplant recipients. Here, we report two adult cases of hepatic abscesses following liver transplantation secondary to adenovirus infection and describe the successful treatment of these patients. Adenovirus should be considered as an uncommon etiology of hepatic abscess and unexplained fevers in adults following liver transplantation.