Insights into cytomegalovirus-associated T cell receptors in recipients following allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Cytomegalovirus (CMV) reactivation is a serious problem in recipients of allogeneic hematopoietic stem cell transplantation. Long-term latency depends on specific T cell immune reconstitution, which identifies various pathogens by T cell receptors (TCRs). However, the mechanisms underlying the selection of CMV-specific TCRs in recipients after transplantation remain unclear. METHODS: Using high-throughput sequencing and bioinformatics analysis, the T cell immune repertoire of seven CMV reactivated recipients (CRRs) were analyzed and compared to those of seven CMV non-activated recipients (CNRs) at an early stage after transplant. RESULTS: The counts of unique complementarity-determining region 3 (CDR3) were significantly higher in CNRs than in CRRs. The CDR3 clones in the CNRs exhibit higher homogeneity compared to the CRRs. With regard to T cell receptor ß-chain variable region (TRBV) and joint region (TRBJ) genotypes, significant differences were observed in the frequencies of TRBV6, BV23, and BV7-8 between the two groups. In addition to TRBV29-1/BJ1-2, TRBV2/BJ2-2, and TRBV12-4/BJ1-5, 11 V-J combinations had significantly different expression levels between CRRs and CNRs. CONCLUSIONS: The differences in TCR diversity, TRBV segments, and TRBV-BJ combinations observed between CNRs and CRRs might be associated with post-transplant CMV reactivation and could serve as a foundation for further research.

Area-Level Social Deprivation and Cytomegalovirus Seropositivity at the Time of Solid Organ Transplant.

Importance: Cytomegalovirus (CMV) is associated with significant morbidity and mortality in solid organ transplant (SOT) recipients. The risk factors for CMV seropositivity in SOT recipients, including area-level social deprivation in the US, have not been fully characterized. Objective: To (1) evaluate CMV seroprevalence, (2) assess the recipient characteristics associated with CMV seropositivity, and (3) assess the association of area-level social deprivation index (SDI) scores with pretransplant CMV serostatus. Design, Setting, and Participants: This retrospective cross-sectional analysis of the Scientific Registry of Transplant Recipients database included all adult (aged ≥18 years) SOT recipients from January 1, 2008, to May 31, 2022. Data were analyzed from April 10 to October 25, 2023. Exposure: Recipient characteristics and area-level SDI. Main Outcomes and Measures: Multivariable generalized linear models were used to evaluate the association between (1) patient characteristics and CMV and (2) social deprivation (measured by SDI scores, which were assessed in quintiles, from lowest to highest) and CMV seropositivity. In addition, differences based on patient demographics and the transplanted organ(s) were evaluated. Results: Among the 389 288 SOT recipients included in the analysis, mean (SD) age was 53.3 (13.0) years; 63.0% were male, 21.4% were Black, 15.2% were Hispanic White, 56.2% were non-Hispanic White, and 62.7% were CMV seropositive. The mean (SD) age was higher among CMV seropositive (54.0 [12.7] years) compared with CMV seronegative (52.0 [13.5] years) patients. Seropositivity for CMV was higher among women (69.9%) than men (58.5%) and among Black (74.8%) and Hispanic White (80.2%) patients compared with non-Hispanic White patients (50.4%). Seropositivity for CMV was highest among kidney (64.5%), liver (63.6%), and kidney and liver (66.2%) recipients. Greater SDI scores were associated with greater CMV seropositivity, ranging from 51.7% for the least deprived to 75.5% for the most deprived quintiles (P < .001), independent of age, sex, or race. Conclusions and Relevance: In this cross-sectional study, an association between SDI and CMV seropositivity was observed among SOT recipients, independent of age, sex, or race and ethnicity. To optimize posttransplant outcomes in CMV seropositive recipients, efforts targeting prevention of CMV reactivation need to be prioritized in these higher-risk populations.

Human cytomegalovirus UL18 prevents priming of MHC-E- and MHC-II-restricted CD8+ T cells.

Rhesus cytomegalovirus (RhCMV) vectors elicit major histocompatibility complex (MHC)-E-restricted CD8+ T cells that stringently control simian immunodeficiency virus (SIV) in rhesus macaques. These responses require deletion of eight RhCMV chemokine-like open reading frames (ORFs) that are conserved in human cytomegalovirus (HCMV). To determine whether HCMV encodes additional, nonconserved inhibitors of unconventional T cell priming, we inserted 41 HCMV-specific ORFs into a chemokine-deficient strain (68-1 RhCMV). Monitoring of epitope recognition revealed that HCMV UL18 prevented unconventional T cell priming, resulting in MHC-Ia-targeted responses. UL18 is homologous to MHC-I but does not engage T cell receptors and, instead, binds with high affinity to inhibitory leukocyte immunoglobulin-like receptor-1 (LIR-1). UL18 lacking LIR-1 binding no longer interfered with MHC-E-restricted T cell stimulation by RhCMV-infected cells or the induction of unconventionally restricted T cells. Thus, LIR-1 binding needs to be deleted from UL18 of HCMV/HIV vaccines to allow for the induction of protective MHC-E-restricted T cells.

Neonatal and short-term outcome after late vertical transmission in congenital CMV-infected fetuses following primary first-trimester maternal seroconversion.

OBJECTIVE: To document the course of neonatal and short-term outcomes in pregnancies after first trimester CMV (cytomegalovirus) seroconversion and negative amniotic fluid (AF) CMV PCR. METHODS: We included 375 patients with a first-trimester CMV seroconversion and amniocentesis at ≥21 weeks. Termination of pregnancy (TOP) was offered in case antenatally severe CMV-related fetopathy was documented either by ultrasound or by MRI. AF CMV PCR-negative fetuses underwent a PCR CMV on neonatal urine (NU). Perinatal and short-term infant outcomes were investigated by a questionnaire, sent to parents. RESULTS: AF CMV PCR was positive in 118/375 cases (31.4%). TOP was performed in 46/118 (38.9%) and fetal demise occurred twice. Questionnaires were sent to 327 patients with an overall response rate of 77%. Three groups were considered: Group 1: the early infected group (AF CMV PCR positive; N=62), group 2: the late infected group (AF CMV PCR negative, NU CMV PCR positive; N=7) and group 3: the control group (AF+NU CMV PCR negative; N=160). Compared with group 3, group 1 was more frequently symptomatic at birth (6.2% vs 19.4%; p=0.006). In short-term follow-up, hearing impairment (23.5%; p<0.001), mild motor deficit - defined as abnormal early motor development or the need for physiotherapy in later life (21.6%; p=0.005) - and subnormal vision (15.7%; p=0.02) were significantly more frequent. Compared with group 3, group 2 showed more often jaundice (57.1%; p=0.04) and petechiae (28.6%; p=0.04) at birth, but other short-term symptoms were lacking. CONCLUSION: Although neonates may screen positive on urine for CMV after an AF CMV negative PCR, they show rarely and only mild sequelae in early life.

Comparison of Cytomegalovirus Reactivation in Children After Allogeneic Hematopoietic Cell Transplantation in 2 Transplant Eras.

BACKGROUND: Reactivation of cytomegalovirus (CMV) is typically considered harmless as long as the immune system remains unaffected by medications or other factors. CMV reactivation may occur as a result of acute graft-versus-host disease of Grades II to IV. One possible factor contributing to this risk is the rise in the number of donors who lack genetic similarities or relationships. We hypothesized that the anti-CMV IgG level before transplantation could potentially serve as an indicator of the likelihood of CMV reactivation following hematopoietic cell transplantation. METHODS: We examined a cohort of young individuals who underwent allogeneic HCT between 1998 and 2022 to evaluate the occurrence of CMV reactivation. The patients were divided into 2 time periods: 1998 to 2016 (comparison group) and 2017 to 2022 (intervention group). RESULTS: Between 1998 and 2016, 292 patients underwent hematopoietic HCT. Recipients from 2017 to 2022 experienced a slightly higher risk of CMV reactivation than those from 1998 to 2016. The comparison of prophylactic and preemptive medication showed no significant difference between the periods (P = .32). Patients treated from 1998 to 2016 experienced a 23% decrease in the risk of symptomatic CMV reactivation and related illnesses compared to those treated from 2017 to 2022 (P = .08 and .15, respectively). CONCLUSIONS: Our study showed that the intervention group had more symptomatic CMV reactivations. Various factors may contribute to this, including CD19-directed immunotherapy and the CMV status of the recipient before transplantation.

Prion protein alters viral control and enhances pathology after perinatal cytomegalovirus infection.

Cytomegalovirus (CMV) infection poses risks to newborns, necessitating effective therapies. Given that the damage includes both viral infection of brain cells and immune system-related damage, here we investigate the involvement of cellular prion protein (PrP), which plays vital roles in neuroprotection and immune regulation. Using a murine model, we show the role of PrP in tempering neonatal T cell immunity during CMV infection. PrP-null mice exhibit enhanced viral control through elevated virus-specific CD8 T cell responses, leading to reduced viral titers and pathology. We further unravel the molecular mechanisms by showing CMV-induced upregulation followed by release of PrP via the metalloproteinase ADAM10, impairing CD8 T cell response specifically in neonates. Additionally, we confirm PrP downregulation in human CMV (HCMV)-infected fibroblasts, underscoring the broader relevance of our observations beyond the murine model. Furthermore, our study highlights how PrP, under the stress of viral pathogenesis, reveals its impact on neonatal immune modulation.

Structure-based design of a soluble human cytomegalovirus glycoprotein B antigen stabilized in a prefusion-like conformation.

Human cytomegalovirus (HCMV) glycoprotein B (gB) is a class III membrane fusion protein required for viral entry. HCMV vaccine candidates containing gB have demonstrated moderate clinical efficacy, but no HCMV vaccine has been approved. Here, we used structure-based design to identify and characterize amino acid substitutions that stabilize gB in its metastable prefusion conformation. One variant containing two engineered interprotomer disulfide bonds and two cavity-filling substitutions (gB-C7), displayed increased expression and thermostability. A 2.8 Å resolution cryoelectron microscopy structure shows that gB-C7 adopts a prefusion-like conformation, revealing additional structural elements at the membrane-distal apex. Unlike previous observations for several class I viral fusion proteins, mice immunized with postfusion or prefusion-stabilized forms of soluble gB protein displayed similar neutralizing antibody titers, here specifically against an HCMV laboratory strain on fibroblasts. Collectively, these results identify initial strategies to stabilize class III viral fusion proteins and provide tools to probe gB-directed antibody responses.

DNA methylation profiling identifies TBKBP1 as potent amplifier of cytotoxic activity in CMV-specific human CD8+ T cells.

Epigenetic mechanisms stabilize gene expression patterns during CD8+ T cell differentiation. Although adoptive transfer of virus-specific T cells is clinically applied to reduce the risk of virus infection or reactivation in immunocompromised individuals, the DNA methylation pattern of virus-specific CD8+ T cells is largely unknown. Hence, we here performed whole-genome bisulfite sequencing of cytomegalovirus-specific human CD8+ T cells and found that they display a unique DNA methylation pattern consisting of 79 differentially methylated regions (DMRs) when compared to memory CD8+ T cells. Among the top demethylated DMRs in cytomegalovirus-specific CD8+ T cells was TBKBP1, coding for TBK-binding protein 1 that can interact with TANK-binding kinase 1 (TBK1) and mediate pro-inflammatory responses in innate immune cells downstream of intracellular virus sensing. Since TBKBP1 has not yet been reported in T cells, we aimed to unravel its role in virus-specific CD8+ T cells. TBKBP1 demethylation in terminal effector CD8+ T cells correlated with higher TBKBP1 expression at both mRNA and protein level, independent of alternative splicing of TBKBP1 transcripts. Notably, the distinct DNA methylation patterns in CD8+ T cell subsets was stable upon long-term in vitro culture. TBKBP1 overexpression resulted in enhanced TBK1 phosphorylation upon stimulation of CD8+ T cells and significantly improved their virus neutralization capacity. Collectively, our data demonstrate that TBKBP1 modulates virus-specific CD8+ T cell responses and could be exploited as therapeutic target to improve adoptive T cell therapies.

T cell responses and clinical symptoms among infants with congenital cytomegalovirus infection.

BACKGROUNDCongenital cytomegalovirus (cCMV) infection can cause developmental impairment and sensorineural hearing loss (SNHL). To determine the relationship between immune responses to cCMV infection and neurologic sequelae, T cell responses were compared for their connection to clinical symptoms at birth and neurodevelopmental outcomes.METHODSThirty cCMV-infected and 15 uninfected infants were enrolled in a single-center prospective observational case-control study. T cell pp65-specific cytokine responses; CD57, CD28, and PD-1 expression; and memory subsets were compared.RESULTSInfected neonates (73% symptomatic at birth) lacked pp65-specific cytokine-secreting T cells, with elevated frequencies of CD57+, CD28-, and PD-1+CD8+ T cells and effector memory subsets. Though frequencies overlapped between cCMV symptom groups, asymptomatic infants had higher frequencies of CD57+PD-1+CD8+ T cells. Neonates with subsequent developmental delay lacked detectable CMV-specific T cell responses, with patterns resembling those of uninfected infants. Two children with progressive SNHL had high frequencies of PD-1+CD8+ T cells over the first year compared with children without progressive SNHL.CONCLUSIONSimilar to published reports, neonatal viral antigen-specific cytokine-secreting T cell responses were not detected, but overall patterns indicate that globally differentiated memory CD8+ T cell populations were induced by cCMV infection, with higher frequencies of terminally differentiated PD-1+CD8+ T cells potentially associated with asymptomatic infection. In this cohort, a lack of in utero T cell differentiation was associated with developmental delay, and high frequencies of PD-1+CD8+ T cells persisted only in children with progressive SNHL. Further work is needed to define the specificity of these T cells and their mechanistic connection to these outcomes.FUNDINGThis study was funded through an intramural research award at Nationwide Children's Hospital, the Pediatric Infectious Disease Society Fellowship Award funded by Stanley and Susan Plotkin and Sanofi Pasteur, the Abigail Wexner Research Institute at Nationwide Children's Hospital, and the Pichichero Family Foundation Vaccines for Children Initiative Research Award from the Pediatric Infectious Diseases Society Foundation.

Immune surveillance of cytomegalovirus in tissues.

Cytomegalovirus (CMV), a representative member of the Betaherpesvirinae subfamily of herpesviruses, is common in the human population, but immunocompetent individuals are generally asymptomatic when infected with this virus. However, in immunocompromised individuals and immunologically immature fetuses and newborns, CMV can cause a wide range of often long-lasting morbidities and even death. CMV is not only widespread throughout the population but it is also widespread in its hosts, infecting and establishing latency in nearly all tissues and organs. Thus, understanding the pathogenesis of and immune responses to this virus is a prerequisite for developing effective prevention and treatment strategies. Multiple arms of the immune system are engaged to contain the infection, and general concepts of immune control of CMV are now reasonably well understood. Nonetheless, in recent years, tissue-specific immune responses have emerged as an essential factor for resolving CMV infection. As tissues differ in biology and function, so do immune responses to CMV and pathological processes during infection. This review discusses state-of-the-art knowledge of the immune response to CMV infection in tissues, with particular emphasis on several well-studied and most commonly affected organs.

Cytomegalovirus-Specific Hyperimmune Immunoglobulin Administration for Secondary Prevention after First-Trimester Maternal Primary Infection: A 13-Year Single-Center Cohort Study.

Primary cytomegalovirus infection during pregnancy has a high risk of vertical transmission, with severe fetal sequelae mainly associated with first-trimester infections. We conducted a retrospective analysis of 200 IU/kg cytomegalovirus-specific hyperimmune globulin (HIG), used in first-trimester maternal primary infections for congenital infection prevention. The primary outcome was vertical transmission, defined as neonatal viruria or positive amniocentesis if pregnancy was discontinued. HIG, initially administered monthly and since 2019 biweekly, was discontinued in negative amniocentesis cases. Women declining amniocentesis and positive amniocentesis cases with normal sonography were offered monthly HIG until delivery as a treatment strategy. The total transmission rate was 29.9% (32/107; 10 pregnancy terminations with positive amniocentesis, 18 completed pregnancies with positive amniocentesis and 4 declining amniocentesis). Maternal viremia was the only factor associated with fetal transmission (OR 4.62, 95% CI 1.55-13.74). The transmission rate was not significantly different whether HIG was started during the first or second trimester (28.2% vs. 33.3%; p = 0.58), or between monthly and biweekly subgroups (25.7% vs. 37.8%, p = 0.193). Pre-treatment maternal viremia could inform decisions as a predictor of congenital infection.

QuantiFERON CMV Test and CMV Serostatus in Lung Transplant: Stratification Risk for Infection, Chronic and Acute Allograft Rejection.

The QuantiFERON CMV (QCMV) test evaluates specific adaptive immune system activity against CMV by measuring IFN-γ released by activated CD8+ T lymphocytes. We aimed to evaluate the QCMV test as a predictive tool for CMV manifestations and acute or chronic lung allograft rejection (AR and CLAD) in lung transplant (LTx) patients. A total of 73 patients were divided into four groups based on donor and recipient (D/R) serology for CMV and QCMV assay: group A low-risk for CMV infection and disease (D-/R-); group B and C at intermediate-risk (R+), group B with non-reactive QCMV and group C with reactive QCMV; group D at high-risk (D+/R-). Group D patients experienced higher viral replication; no differences were observed among R+ patients of groups B and C. D+/R- patients had a higher number of AR events and group C presented a lower incidence of AR. Prevalence of CLAD at 24 months was higher in group B with a higher risk of CLAD development (OR 6.33). The QCMV test allows us to identify R+ non-reactive QCMV population as the most exposed to onset of CLAD. This population had a higher, although non-significant, susceptibility to AR compared to the R+ population with reactive QCMV.

Regulation of the cell surface expression of classical and non-classical MHC proteins by the human cytomegalovirus UL40 and rhesus cytomegalovirus Rh67 proteins.

The signal sequences of the human cytomegalovirus (CMV) UL40 protein and its rhesus CMV (RhCMV) counterpart, Rh67, contain a peptide (VMAPRT[L/V][F/I/L/V]L, VL9) that is presented by major histocompatibility complex (MHC) antigen E (MHC-E). The CMV VL9 peptides replace VL9 peptides derived from classical MHC (Ia) signal sequences, which are lost when CMV disrupts antigen processing and presentation and MHC Ia expression. This allows infected cells to maintain MHC-E surface expression and escape killing by Natural Killer cells. We demonstrate that processing of the Rh67 VL9 peptide mirrors that of UL40, despite the lack of sequence conservation between the two proteins. Processing of both VL9 peptides is dependent on cleavage of their signal sequences by the host protease signal peptide peptidase. As previously shown for UL40, up-regulation of MHC-E expression by Rh67 requires only its signal sequence, with sequences upstream of VL9 critical for conferring independence from TAP, the transporter associated with antigen processing. Our results also suggest that the mature UL40 and Rh67 proteins contribute to CMV immune evasion by decreasing surface expression of MHC Ia. Unexpectedly, while the Rh67 VL9 peptide is resistant to the effects of Rh67, UL40 can partially counteract the up-regulation of MHC-E expression mediated by its own VL9 peptide. This suggests differences in the mechanisms by which the two VL9 peptides up-regulate MHC-E, and further work will be required to determine if any such differences have implications for translating a RhCMV-vectored simian immunodeficiency virus (SIV) vaccine to HIV-1 using human CMV as a vector. IMPORTANCE: The protective immune response induced by a rhesus cytomegalovirus (RhCMV)-vectored simian immunodeficiency virus (SIV) vaccine in rhesus macaques depends on the presence of the viral Rh67 gene in the vaccine. The Rh67 protein contains a peptide that allows the RhCMV-infected cells to maintain expression of major histocompatibility complex (MHC) antigen E at the cell surface. We show that production of this peptide, referred to as "VL9," mirrors that of the equivalent peptide present in the human cytomegalovirus (CMV) protein UL40, despite the little sequence similarity between the two CMV proteins. We also show that the mature UL40 and Rh67 proteins, which have no previously described function, also contribute to CMV immune evasion by reducing cell surface expression of MHC proteins important for the immune system to detect infected cells. Despite these similarities, our work also reveals possible differences between Rh67 and UL40, and these may have implications for the use of human CMV as the vector for a potential HIV-1 vaccine.

Worse Wilms' Tumor Outcomes Associated With Chemical Complementarity for Multiple T-Cell Receptor CDR3-CMV Epitope Pairs.

BACKGROUND/AIM: Wilms' tumors are pediatric renal tumors that generally have a good prognosis and outcomes. Viral illnesses have been linked to development of neoplasms and should be considered as a factor that could modulate overall survival. MATERIALS AND METHODS: We considered recently developed adaptive immune receptor, genomics and bioinformatics approaches to assess the potential impact of cytomegalovirus (CMV) infections in Wilms' tumor. RESULTS: T-cell receptor (TCR) complementarity determining region-3 (CDR3) amino acid sequences from Wilms' tumor specimens represented by the Therapeutically Applicable Research to Generate Effective Treatments dataset were compared with known anti-CMV TCR CDR3s, indicating that cases representing the anti-CMV TCR CDR3s had worse outcomes. Then, a chemical complementarity scoring approach for the Wilms' tumor, TCR CDR3s and a series of CMV antigens further indicated that cases representing a higher chemical complementarity to the CMV antigens had worse outcomes. CONCLUSION: Overall, we present a potentially novel method to assess CMV infections and identify patients who could benefit from therapies that address such infections.

Antiviral Agents for Preventing Cytomegalovirus Disease in Recipients of Hematopoietic Cell Transplantation.

This systematic review discusses the use of prophylaxis to prevent cytomegalovirus (CMV) infection in recipients who have undergone hematopoietic cell transplantation. It highlights the need for new approaches to control and prevent CMV infection. The approval of the anti-CMV drug letermovir has made antiviral prophylaxis more popular. CMV-specific T cell-mediated immunity tests are effective in identifying patients who have undergone immune reconstitution and predicting disease progression. Maribavir (MBV) has been approved for the treatment of post-transplant CMV infection/disease in adolescents. Adoptive T-cell therapy and the PepVax CMV vaccine show promise in tackling refractory and resistant CMV. However, the effectiveness of PepVax in reducing CMV viremia/disease was not demonstrated in a phase II trial. Cell-mediated immunity assays are valuable for personalized management plans, but more interventional studies are needed. MBV and adoptive T-cell therapy are promising treatments, and trials for CMV vaccines are ongoing.

Predicting T cell receptor functionality against mutant epitopes.

Cancer cells and pathogens can evade T cell receptors (TCRs) via mutations in immunogenic epitopes. TCR cross-reactivity (i.e., recognition of multiple epitopes with sequence similarities) can counteract such escape but may cause severe side effects in cell-based immunotherapies through targeting self-antigens. To predict the effect of epitope point mutations on T cell functionality, we here present the random forest-based model Predicting T Cell Epitope-Specific Activation against Mutant Versions (P-TEAM). P-TEAM was trained and tested on three datasets with TCR responses to single-amino-acid mutations of the model epitope SIINFEKL, the tumor neo-epitope VPSVWRSSL, and the human cytomegalovirus antigen NLVPMVATV, totaling 9,690 unique TCR-epitope interactions. P-TEAM was able to accurately classify T cell reactivities and quantitatively predict T cell functionalities for unobserved single-point mutations and unseen TCRs. Overall, P-TEAM provides an effective computational tool to study T cell responses against mutated epitopes.

Late-life Attenuation of Cytomegalovirus-mediated CD8 T Cell Memory Inflation: Shrinking of the Cytomegalovirus Latency Niche.

CMV drives the accumulation of virus-specific, highly differentiated CD8 memory T cells (memory inflation [MI]). In mice, MI was shown to directly correlate with the CMV infection dose, yet the CMV-associated CD8 MI plateaus over time. It is unclear how MI is regulated with aging. We infected young mice with 102, 104, and 106 PFU of murine CMV and confirmed that MI magnitude was directly proportional to the infectious dose, reaching a setpoint by midlife. By old age, MI subsided, most prominently in mice infected with 106 PFU, and reached statistical parity between groups in 26-mo-old mice. This corresponded to an age-related loss in lymphatic endothelial cells in lymph nodes, recently shown to be sufficient to drive MI in mice. We propose that MI size and persistence over the lifespan is controlled by the size of the lymphatic endothelial cell niche, whose shrinking leads to reduced MI with aging.

Cytomegalovirus immunity in high-risk liver transplant recipients following preemptive antiviral therapy versus prophylaxis.

CMV-specific T cells, NK cells, and neutralizing antibodies (nAbs) were assessed in a randomized trial of CMV prevention with preemptive antiviral therapy (PET) versus prophylactic antiviral therapy (PRO) in donor-seropositive/recipient-seronegative (D+R-) liver transplant recipients (LTxR) at 100 days (end of intervention) and at 6 and 12 months after transplant. The PET group had significantly increased numbers of circulating polyfunctional T cells, NK cells, and nAbs compared with the PRO group at day 100, and several CMV immune parameters remained significantly higher by 12 months after transplant. Among PET recipients, preceding CMV viremia (vs. no preceding viremia) was associated with significantly higher levels of most CMV immune parameters at day 100. Higher numbers of CMV-specific polyfunctional T cells and NKG2C+ NK cells at day 100 were associated with a decreased incidence of CMV disease in multivariable Cox regression. The strongest associations with protection against CMV disease were with increased numbers of CMV-specific polyfunctional CD4+ T cells, CD3negCD56dimCD57negNKG2Cpos cells, and CD3negCD56dimCD57posNKG2Cpos NK cells. Our results suggest that PET is superior to PRO for CMV disease prevention by allowing low-level CMV replication and associated antigen exposure that is promptly controlled by antiviral therapy and facilitates enhanced CMV protective immunity in D+R- LTxR.

Cutting Edge: Retinoic Acid Promotes Brain-homing of CD8+ T Cells during Congenital Cytomegalovirus Infection.

The most common congenital viral infection is CMV, which leads to numerous neurologic disabilities. Using a mouse model of congenital CMV, we previously determined that Ag-specific CD8+ T cells traffic to the brain in a CCR9-dependent manner. The mechanism by which these CD8+ T cells acquire a CCR9-dependent "brain-tropic" phenotype remains unclear. In this study, we identify the key factor that imprints brain homing specificity on CD8+ T cells, the source of production, and the location where CCR9 expression is induced. Specifically, we discovered that CCR9 is induced on CD8+ T cells by retinoic acid-producing CD8α+ dendritic cells in the cervical lymph node postinfection. We found that retinoic acid is important for CD8+ T cells to establish tissue residency in the brain. Collectively, our data expand the role of retinoic acid during infection and mechanistically demonstrate how CD8+ T cells are primed to protect the brain during congenital viral infection.

Discrimination of primary and chronic cytomegalovirus infection based on humoral immune profiles in pregnancy.

BACKGROUNDMost humans have been infected with cytomegalovirus (CMV) by midlife without clinical signs of disease. However, in settings in which the immune system is undeveloped or compromised, the virus is not adequately controlled and consequently presents a major infectious cause of both congenital disease during pregnancy as well as opportunistic infection in children and adults. With clear evidence that risk to the fetus varies with gestational age at the time of primary maternal infection, further research on humoral responses to primary CMV infection during pregnancy is needed.METHODSHere, systems serology tools were applied to characterize antibody responses to CMV infection in pregnant and nonpregnant women experiencing either primary or chronic infection.RESULTSWhereas strikingly different antibody profiles were observed depending on infection status, limited differences were associated with pregnancy status. Beyond known differences in IgM responses used clinically for identification of primary infection, distinctions observed in IgA and FcγR-binding antibodies and among antigen specificities accurately predicted infection status. Machine learning was used to define the transition from primary to chronic states and predict time since infection with high accuracy. Humoral responses diverged over time in an antigen-specific manner, with IgG3 responses toward tegument decreasing over time as typical of viral infections, while those directed to pentamer and glycoprotein B were lower during acute and greatest during chronic infection.CONCLUSIONIn sum, this work provides insights into the antibody response associated with CMV infection status in the context of pregnancy, revealing aspects of humoral immunity that have the potential to improve CMV diagnostics.FUNDINGCYMAF consortium and NIH NIAID.