Cytomegalovirus (CMV) research in immune senescence comes of age: overview of the 6th International Workshop on CMV and Immunosenescence

Relations of optimism and purpose in life to immune markers in aging

OBJECTIVE

Optimism and purpose in life are associated with improved health outcomes. More information is needed on biological mechanisms, including immunosenescence. We investigated if psychological well-being is associated with healthier immunosenescence-related measures including naïve and terminally differentiated CD4+ and CD8+ T cell percentages, CD4+:CD8+, and cytomegalovirus (CMV) IgG response.

METHODS

Participants were adults over age 50 from the Health and Retirement Study. Optimism was measured using the Life Orientation Test Revised. Purpose in life was assessed using the subscale from the Ryff psychological well-being measure. We examined the cross-sectional associations of optimism and purpose in life with measures of T cell subsets using linear regression and with CMV IgG using ordered logit regression, controlling for potential confounding factors.

RESULTS

The final analytic sample ranged from 7250 to 7870. After adjusting for sociodemographic factors, a 1-SD increment in optimism was associated with the percentage of naïve CD4+ T cells increasing by 0.6 (95%CI 0.2%, 1.0%). A 1-SD increment in purpose in life was associated with the percentage of naïve CD4+ T cells increasing by 0.9 (95%CI 0.5%, 1.3%) after adjusting for sociodemographic factors and the association was maintained after further adjustments for health conditions, depression, and health behaviors. For naïve CD8+ T cell percentages, CD4:CD8 ratios, and CMV IgG antibodies, associations were seen only in models that adjusted for age. No significant associations were seen in any models for the terminally differentiated CD4+ and CD8+ T cells.

CONCLUSIONS

We found associations of optimism and purpose in life with naïve CD4+ T cell percentages.

Human cytomegalovirus UL23 exploits PD-L1 inhibitory signaling pathway to evade T cell-mediated cytotoxicity

Human cytomegalovirus (HCMV), a widely prevalent human beta-herpesvirus, establishes lifelong persistence in the host following primary infection. In healthy individuals, the virus is effectively controlled by HCMV-specific T cells and typically exhibits asymptomatic. The T cell immune response plays a pivotal role in combating HCMV infection, while HCMV employs various strategies to counteract it within the host. Previously, we reported that UL23, a tegument protein of HCMV, facilitates viral immune evasion from interferon-gamma (IFN-γ) responses, and it is well known that IFN-γ is mainly derived from T cells. However, the involvement of UL23 in viral immune evasion from T cell-mediated immunity remains unclear. Herein, we present compelling evidence that UL23 significantly enhances viral resistance against T cell-mediated cytotoxicity during HCMV infection from the co-culture assays of HCMV-infected cells with T cells. We found that IFN-γ plays a major role in regulating T cell cytotoxicity mediated by UL23. More interestingly, we demonstrated that UL23 not only regulates the IFN-γ downstream responses but also modulates the IFN-γ secretion by regulating T cell activities. Further experiments indicate that UL23 upregulates the expression and signaling of programmed death ligand 1 (PD-L1), which is responsible for inhibiting multiple aspects of T cell activities, including activation, apoptosis, and IFN-γ secretion, as determined through RNA-seq analysis and inhibitor-blocking experiments, ultimately facilitating viral replication and spread. Our findings highlight the potential role of UL23 as an alternative antagonist in suppressing T cell cytotoxicity and unveil a novel strategy for HCMV to evade T cell immunity.

IMPORTANCE

T cell immunity is pivotal in controlling primary human cytomegalovirus (HCMV) infection, restricting periodic reactivation, and preventing HCMV-associated diseases. Despite inducing a robust T cell immune response, HCMV has developed sophisticated immune evasion mechanisms that specifically target T cell responses. Although numerous studies have been conducted on HCMV-specific T cells, the primary focus has been on the impact of HCMV on T cell recognition via major histocompatibility complex molecules. Our studies show for the first time that HCMV exploits the programmed death ligand 1 (PD-L1) inhibitory signaling pathway to evade T cell immunity by modulating the activities of T cells and thereby blocking the secretion of IFN-γ, which is directly mediated by HCMV-encoded tegument protein UL23. While PD-L1 has been extensively studied in the context of tumors and viruses, its involvement in HCMV infection and viral immune evasion is rarely reported. We observed an upregulation of PD-L1 in normal cells during HCMV infection and provided strong evidence supporting its critical role in UL23-induced inhibition of T cell-mediated cytotoxicity. The novel strategy employed by HCMV to manipulate the inhibitory signaling pathway of T cell immune activation for viral evasion through its encoded protein offers valuable insights for the understanding of HCMV-mediated T cell immunomodulation and developing innovative antiviral treatment strategies.

Cytomegalovirus Diseases of the Gastrointestinal Tract in Immunocompetent Patients: A Narrative Review

Cytomegalovirus (CMV) is a potential pathogen that causes gastrointestinal (GI) tract diseases regardless of host immunity. In contrast to immunocompromised individuals, immunocompetent patients lack a comprehensive overview of the gastrointestinal manifestations. This study aims to provide a comprehensive summary of the current evidence regarding presentations, diagnostics, management, risk assessment, and outcomes in immunocompetent patients with CMV GI disease. A thorough literature search of English publications up to April 2022 was conducted across electronic databases to identify relevant articles, with eligible case series selected for detailed analysis. The majority of immunocompetent patients affected by CMV GI disease are typically elderly, critically ill, or burdened with comorbidities that compromise immunity. Clinical presentations range from subtle symptoms to severe surgical conditions, including instances of mortality. Specific clinical presentations, blood test results, or endoscopic features are lacking, necessitating reliance on histopathological tests such as immunohistochemistry staining for diagnosis. While antiviral therapy may offer benefits in improving outcomes, careful individual assessment is warranted due to diverse comorbidities and potential side effects. Mortality rates vary considerably based on underlying medical conditions and therapeutic approaches. It is imperative for clinicians to maintain vigilance for CMV GI disease among high-risk groups, despite their baseline immunocompetence, in order to enhance clinical outcomes.

Activation of senescence in critically ill patients: mechanisms, consequences and therapeutic opportunities

Whereas aging is a whole-organism process, senescence is a cell mechanism that can be triggered by several stimuli. There is increasing evidence that critical conditions activate cell senescence programs irrespective of patient's age. In this review, we briefly describe the basic senescence pathways and the consequences of their activation in critically ill patients. The available evidence suggests a paradigm in which activation of senescence can be beneficial in the short term by rendering cells resistant to apoptosis, but also detrimental in a late phase by inducing a pro-inflammatory and pro-fibrotic state. Senescence can be a therapeutic target. The use of drugs that eliminate senescent cells (senolytics) or the senescence-associated phenotype (senomorphics) will require monitoring of these cell responses and identification of therapeutic windows to improve the outcome of critically ill patients.

Sicilian semi- and supercentenarians: identification of age-related T-cell immunophenotype to define longevity trait

The immunophenotype of oldest centenarians, i.e. semi- and supercentenarians, could provide important information about their ability to adapt to factors associated with immune changes, including ageing per se and chronic Cytomegalovirus infection. We investigated, by flow cytometry, variations in percentages and absolute numbers of immune cell subsets, focusing on T cells, and pro-inflammatory parameters in a cohort of 28 women and 26 men (age range 19-110 years). We observed variability in hallmarks of immunosenescence related to age and Cytomegalovirus serological status. The eight oldest centenarians showed the lowest percentages of naïve T cells, due to their age, and the highest percentages of T-effector memory cells re-expressing CD45RA (TEMRA), according to their cytomegalovirus status, and high levels of serum pro-inflammatory parameters, although their means were lower than that of remaining 90+ donors. Some of them showed CD8 naïve and TEMRA percentages, and exhaustion/pro-inflammatory markers comparable to the younger ones. Our study supports the suggestion that immune ageing, especially of oldest centenarians, exhibits great variability that is not only attributable to a single contributor but should also be the full result of a combination of several factors. Everyone ages differently because he/she is unique in genetics and experience of life and this applies even more to the immune system; everybody has had a different immunological history. Furthermore, our findings on inflammatory markers, TEMRA and CMV seropositivity in centenarians, discussed in the light of the most recent literature, suggest that these changes might be not unfavourable for centenarians, and in particular for the oldest ones.

Baseline immune states (BIS) associated with vaccine responsiveness and factors that shape the BIS

Vaccines are among the greatest inventions in medicine, leading to the elimination or control of numerous diseases, including smallpox, polio, measles, rubella, and, most recently, COVID-19. Yet, the effectiveness of vaccines varies among individuals. In fact, while some recipients mount a robust response to vaccination that protects them from the disease, others fail to respond. Multiple clinical and epidemiological factors contribute to this heterogeneity in responsiveness. Systems immunology studies fueled by advances in single-cell biology have been instrumental in uncovering pre-vaccination immune cell types and genomic features (i.e., the baseline immune state, BIS) that have been associated with vaccine responsiveness. Here, we review clinical factors that shape the BIS, and the characteristics of the BIS associated with responsiveness to frequently studied vaccines (i.e., influenza, COVID-19, bacterial pneumonia, malaria). Finally, we discuss potential strategies to enhance vaccine responsiveness in high-risk groups, focusing specifically on older adults.

Premature T cell aging in major depression: A double hit by the state of disease and cytomegalovirus infection

Introduction

Previous research indicates that premature T cell senescence is a characteristic of major depressive disorder (MDD). However, known senescence inducing factors like cytomegalovirus (CMV) infection or, probably, childhood adversity (CA) have not been taken into consideration so far.

Objective

Differentiation and senescent characteristics of T cells of MDD patients were investigated in relation to healthy controls (HC), taking the CMV seropositivity and CA into account.

Methods

127 MDD and 113 HC of the EU-MOODSTRATIFICATION cohort were analyzed. Fluorescence activated cell sorting (FACS) analysis was performed to determine B, NK, and T cell frequencies. In a second FACS analysis, naïve, effector memory (Tem), central memory (Tcm), effector memory cells re-expressing RA (TEMRA), as well as CD28⁺ and CD27⁺ memory populations, were determined of the CD4⁺ and CD8⁺ T cell populations in a subsample (N = 35 MDD and N = 36 HC). CMV-antibody state was measured by IgG ELISA and CA by the Childhood Trauma Questionnaire.

Results

We detected a CMV-antibody positivity in 40% of MDD patients (35% HC, n. s.) with seropositive MDD cases showing a higher total childhood trauma score. Second, a higher inflation of memory CD4⁺ T helper cells in CMV seronegative patients as compared to seronegative HC and reduced numbers of naïve CD4⁺ T helper cells in CMV seropositive patients (not in CMV seropositive HC) were found. Third, a higher inflation of memory CD8⁺ T cytotoxic cells in CMV seropositive cases as compared to CMV seropositive HC, particularly of the TEMRA cells, became apparent. Higher percentages of CD4⁺ TEMRA and late stage CD27^-CD28^- TEMRA cells were similar in both HC and MDD with CMV seropositivity. Overall, apportioning of T cell subpopulations did not differ between CA positive vs negative cases.

Conclusions

MDD patients show several signs of a CMV independent "MDD specific" premature T cell aging, such as a CMV independent increase in CD4⁺ T memory cells and a latent naïve CD4 T-cell reduction and a latent CD8⁺ T-cell increase. However, these two latent T cell senescence abnormalities only become evident with CMV infection (double hit).

Prognosis of Human Cytomegalovirus in Cancer Patients Undergoing Chemotherapeutic Treatment in Egypt and an Emergent Prevalence of Glycoprotein B-5

The human cytomegalovirus (HCMV) is a global opportunistic β-herpes virus causing severe diseases in immune-compromised patients, such as malignant tumor patients, especially those undergoing chemotherapeutic treatment. This study aimed to determine the prevalence of HCMV-DNA in chemotherapeutic treatment naive cancer patients, and after chemotherapy, to compare between conventional nested PCR and ELISA techniques for the detection of HCMV, and to detect glycoprotein B genotypes. Plasma and serum samples before and after three chemotherapy cycles were collected from 49 chemotherapy-naive cancer patients. DNA was extracted from plasma samples using QIAamp® DNA Mini kit. HCMV-DNA was detected using a nested PCR technique. Multiplex nested PCR was used for HCMV-glycoprotein B (gB) genotyping. HCMV-IgG and -IgM were detected using ELISA technique. Thirty one (63.3 %) of the 49 plasma samples of the chemotherapy-naïve cancer patients were positive for HCMV-DNA; 21 of which remained positive after chemotherapy. However, 18 samples were negative of which 16 became positive after chemotherapy. gB-5 was the most common glycoprotein genotype detected (80.6 %), followed by gB-1, gB-3, gB-4, and gB-2. HCMV IgG was detected in the 49 serum samples of chemotherapy-naïve patients, and after exposure to chemotherapy. HCMV-DNA is commonly identified in cancer patients. Its detection after chemotherapy exposure may suggest HCMV reactivation. The most common genotype detected in cancer patients in Egypt is gB-5 in contrast to earlier research. IgG was detected in all patients. This indicates that HCMV is endemic in Egypt, necessitating the development of public awareness campaigns about HCMV infection and preventive strategies.

Investigating population-level immunosenescence: From bench to bedside

The immune response is remodeled with aging in a process called immunosenescence. Some immunologists conceive immunosenescence as an adaptation of immunity to the aged immune-environment rather than a merely collapsed reactivity of immune cells against microbes and tumor cells. Others believe on an uninterrupted activation of the innate immune system with aging, leading to a low grade, sterile and chronic proinflammatory state called inflammaging. For instance, it is possible that chronic infection by cytomegalovirus leads to persistent production of viral load. This phenomenon offers periodic stimuli to the immune system that ultimately contribute to the remodeling of the immune response. If investigating immunosenescence at the cellular level is already a difficult task, considering the population level is much more complex. However, by studying immunosenescence at the population level, we can extract valuable results with viable applications. While studies with animal models allow scientists to deepen their understanding of the mechanisms of immunosenescence, studying large populations can bring practical innovations to medicine and the health system. Many researchers and funders have dedicated themselves to producing methods for the evaluation of immunosenescence on a large scale, aiming to elucidate new mechanisms by which diseases are established in the elderly. The description of how the immune response is remodeled with aging emerges as a new tool to identify the subset of subjects in which unhealthy aging is a matter of time, to help better individualize clinical management and select patients who may benefit. of early interventions. This review focuses on functional assays as valuable methods for measuring the remodeling of the immune response with aging and discuss their clinical impact. We also recall fundamental concepts for understanding the aging process of the immune response. In addition, we highlight future prospects for immunosenescence research.

T cell senescence and impaired CMV-specific response are associated with infection risk in kidney transplant recipients

Older kidney transplant recipients demonstrate increased rates of infection, and lower rates of rejection, compared with younger kidney transplant recipients. However, the mechanism behind this observation remains unknown. To develop a multifaceted view of age-associated immune dysfunction, we determined the function and phenotype of T cells predisposing to vulnerability to infection on a molecular level. Overlapping peptide pools representing the dominant CMV antigens were used to stimulate PBMC collected from 51 kidney transplant recipients, using cytokine secretion to determine specificity and intensity of response. Staphylococcal endotoxin B (SEB) was analyzed in parallel. To define immune cell subsets, we used single cell RNA sequencing (scRNAseq) to evaluate cellular surface markers and gene expression. We found increased frequency of SEB- and CMV-specific T cells was associated with freedom from infection, especially in older patients. Spatialized t-SNE analysis revealed decreased frequency of naïve T cells, increased frequency of TEMRA cells, and decreased frequency of IFNγ secreting T cells in patients with infection. Application of scRNAseq analysis revealed increased frequency of terminally differentiated T cells expressing NK-associated receptors and inhibitory markers. These findings offer unique insight into the mechanism behind vulnerability to infection in the kidney transplant recipient, revealing a specific T cell subtype of impaired antigen response and terminal effector phenotype as markers of T cell senescence.

Understanding the interaction between cytomegalovirus and tuberculosis in children: The way forward

Over 1 million children develop tuberculosis (TB) each year, with a quarter dying. Multiple factors impact the risk of a child being exposed to Mycobacterium tuberculosis (Mtb), the risk of progressing to TB disease, and the risk of dying. However, an emerging body of evidence suggests that coinfection with cytomegalovirus (CMV), a ubiquitous herpes virus, impacts the host response to Mtb, potentially influencing the probability of disease progression, type of TB disease, performance of TB diagnostics, and disease outcome. It is also likely that infection with Mtb impacts CMV pathogenesis. Our current understanding of the burden of these 2 diseases in children, their immunological interactions, and the clinical consequence of coinfection is incomplete. It is also unclear how potential interventions might affect disease progression and outcome for TB or CMV. This article reviews the epidemiological, clinical, and immunological literature on CMV and TB in children and explores how the 2 pathogens interact, while also considering the impact of HIV on this relationship. It outlines areas of research uncertainty and makes practical suggestions as to potential studies that might address these gaps. Current research is hampered by inconsistent definitions, study designs, and laboratory practices, and more consistency and collaboration between researchers would lead to greater clarity. The ambitious targets outlined in the World Health Organization End TB Strategy will only be met through a better understanding of all aspects of child TB, including the substantial impact of coinfections.

Natural Products and Their Derivatives against Human Herpesvirus Infection

Herpesviruses establish long-term latent infection for the life of the host and are known to cause numerous diseases. The prevalence of viral infection is significantly increased and causes a worldwide challenge in terms of health issues due to drug resistance. Prolonged treatment with conventional antiviral drugs is more likely to develop drug-resistant strains due to mutations of thymidine nucleoside kinase or DNA polymerase. Hence, the development of alternative treatments is clearly required. Natural products and their derivatives have played a significant role in treating herpesvirus infection rather than nucleoside analogs in drug-resistant strains with minimal undesirable effects and different mechanisms of action. Numerous plants, animals, fungi, and bacteria-derived compounds have been proved to be efficient and safe for treating human herpesvirus infection. This review covers the natural antiherpetic agents with the chemical structural class of alkaloids, flavonoids, terpenoids, polyphenols, anthraquinones, anthracyclines, and miscellaneous compounds, and their antiviral mechanisms have been summarized. This review would be helpful to get a better grasp of anti-herpesvirus activity of natural products and their derivatives, and to evaluate the feasibility of natural compounds as an alternative therapy against herpesvirus infections in humans.

Interspecific interactions that affect ageing: Age-distorters manipulate host ageing to their own evolutionary benefits

Genetic causes for ageing are traditionally investigated within a species. Yet, the lifecycles of many organisms intersect. Additional evolutionary and genetic causes of ageing, external to a focal species/organism, may thus be overlooked. Here, we introduce the phrase and concept of age-distorters and its evidence. Age-distorters carry ageing interfering genes, used to manipulate the biological age of other entities upon which the reproduction of age-distorters relies, e.g. age-distorters bias the reproduction/maintenance trade-offs of cells/organisms for their own evolutionary interests. Candidate age-distorters include viruses, parasites and symbionts, operating through specific, genetically encoded interferences resulting from co-evolution and arms race between manipulative non-kins and manipulable species. This interference results in organismal ageing when age-distorters prompt manipulated organisms to favor their reproduction at the expense of their maintenance, turning these hosts into expanded disposable soma. By relying on reproduction/maintenance trade-offs affecting disposable entities, which are left ageing to the reproductive benefit of other physically connected lineages with conflicting evolutionary interests, the concept of age-distorters expands the logic of the Disposable Soma theory beyond species with fixed germen/soma distinctions. Moreover, acknowledging age-distorters as external sources of mutation accumulation and antagonistic pleiotropic genes expands the scope of the mutation accumulation and of the antagonistic pleiotropy theories.

CytomegaloVirusDb: Multi-omics knowledge database for cytomegaloviruses

Cytomegalovirus infection is a significant health concern and need further exploration in immunologic response mechanisms during primary and reactivated CMV infection. In this work, we evaluated the whole genomes and proteomes of different CMV species and developed an integrated open-access platform, CytomegaloVirusDb, a multi-Omics knowledge database for Cytomegaloviruses. The resource is categorized into the main sections "Genomics," "Proteomics," "Immune response," and "Therapeutics,". The database is annotated with the list of all CMV species included in the study, and available information is freely accessible at http://www.cmvdb.dqweilab-sjtu.com/index.php. Various parameters used in the analysis for each section were primarily based on the whole genome or proteome of each specie. The platform provided datasets are open to access for researchers to obtain CMV species-specific information. This will help further to explore the dynamics of CMV-specific immune response and therapeutics. This platform is a useful resource to aid in advancing research against Cytomegaloviruses.

Donor Graft Cytomegalovirus Serostatus and the Risk of Arterial and Venous Thrombotic Events in Seronegative Recipients After Non-Thoracic Solid Organ Transplantation

BACKGROUND

Cytomegalovirus (CMV) is the most common opportunistic pathogen, following solid organ transplantation (SOT), that leads to direct and indirect effects. The aim of this study was to assess the impact of CMV exposure at transplantation on the rate of posttransplant thrombotic events (TEs).

METHODS

We conducted a retrospective cohort study of patients transplanted at the University of Alberta Hospital between July 2005 and January 2018. We included adult SOT CMV-seronegative recipients at transplantation who received an allograft from either a seropositive donor (D+/R-) or a seronegative donor (D-/R-).

RESULTS

A total of 392 SOT recipients were included: 151 (39%) liver, 188 (48%) kidney, 45 (11%) pancreas, and 8 (2%) other transplants. The mean age was 47 years, 297 (76%) were males, and 181 (46%) had a CMV D+/R- donor. Patients in the CMV D+/R- cohort were slightly older (51 years versus 48 years in the D-/R- cohort; P = .036), while other variables, including cardiovascular risk factors and pretransplant TEs, were not different between groups. Overall, TEs occurred in 35 (19%) patients in the CMV D+/R- group, versus 21 (10%) in the CMV D-/R- group, at 5 years of follow-up (P = .008); the incidence rates per 100 transplant months were 5.12 and 1.02 in the CMV D+/R- and CMV D-/R- groups, respectively (P = .003). After adjusting for potential confounders with a Cox regression model, a CMV D+/R- transplantation was independently associated with an increased risk of a TE over 5 years (adjusted hazard ratio, 3.027; 95% confidence interval, 1.669-5.488).

CONCLUSIONS

A CMV D+/R- transplantation is associated with an increased risk of a TE posttransplantation.

Cytomegalovirus Infection and Its Relationship with Leukocyte Telomere Length: A Cross-Sectional Study

Background

Telomeres undergo shortening with each cell division, which could be accelerated by infection. The association between virus infection and telomere length is poorly understood. In the present study, we investigated the putative associations between leukocyte telomere length (TL), cytomegalovirus (CMV) infection, and C-reactive protein (CRP) in a national representative sample of noninstitutionalized population.

Methods

We analyzed data that was collected in a cross-sectional setting, where 3,987 participants were enrolled with available data on telomere length. The association between telomere length with previous CMV infection and CRP was analyzed using multivariable linear regression models. We further tested if obesity, measured by body mass index (BMI), and smoking could modify this relationship.

Results

In total, around 46% percent of the study population were men and 54% were women. Average ages were 35.1 years for men and 35.0 years for women. One unit increase of CMV antibody IgG titer was associated with -0.07 (95% confidence interval: -0.12, -0.01) unit decrease of leukocyte TL when sex was adjusted for. After additionally adjusting for BMI and smoking status, the magnitude of the association was only slightly decreased to -0.06 (95% confidence interval: -0.11, -0.01). The effect sizes were comparable after additionally adjusting for CRP. These analyses imply that previous CMV infection affects leukocyte TL through pathways other than CRP.

Conclusions

Previous CMV infection was associated with shorter leukocyte TL. This association was independent of CRP.

Predictive factors of human cytomegalovirus reactivation in newly diagnosed glioblastoma patients treated with chemoradiotherapy

The human cytomegalovirus (HCMV) is a ubiquitous herpes virus which infects 40 to 99% of the population. HCMV reactivation may occur in the context of immunosuppression and can induce significant morbidities. Several cases of HCMV infections or HCMV reactivation have thus been reported in glioblastoma (GBM) patients treated with radio(chemo)therapy. With the aim to identify the main risk factors associated with HCMV reactivation, we reviewed all patients treated for a newly diagnosed GBM in our institution from October 2013 to December 2015. Age, sex, Karnofsky performance status (KPS), absolute lymphocyte count (ALC), serological HCMV status, and steroid doses were recorded at the start and 1 month after the end of radiotherapy (RT). Within the 103 patients analyzed, 34 patients (33%) had an initial negative serology for HCMV, and none of them developed a seroconversion after treatment. Among patients with positive HCMV IgG (n = 69), 16 patients (23%) developed a viremia at one point during treatment. Age (> 60 years), steroid intake, and ALC (< 1500/mm³) before RT were correlated with HCMV reactivation. HCMV viremia was associated with neurological decline 1 month after chemoradiotherapy but progression-free survival was not impacted. A shorter overall survival was seen in these patients when compared with the others, but this could be biased by the older age in this subgroup. HCMV reactivation needs to be sought in case of a neurological decline during RT especially in older patients treated with steroids and low lymphocytes counts.

CD56-negative NK cells with impaired effector function expand in CMV and EBV co-infected healthy donors with age

Natural killer cells lacking expression of CD56 (CD56^neg NK cells) have been described in chronic HIV and hepatitis C virus infection. Features and functions of CD56^neg NK cells in the context of latent infection with CMV and / or EBV with age are not known. In a cohort of healthy donors >60 years of age, we found that co-infection with CMV and EBV drives expansion of CD56^neg NK cells. Functionally, CD56^neg NK cells displayed reduced cytotoxic capacity and IFN-γ production, a feature that was enhanced with CMV / EBV co-infection. Further, the frequency of CD56^neg NK cells correlated with accumulation of end-stage-differentiated T cells and a reduced CD4 / CD8 T cell ratio, reflecting an immune risk profile. CD56^neg NK cells had a mature phenotype characterized by low CD57 and KIR expression and lacked characteristics of cell senescence. No changes in their activating NK cell receptor expression, and no upregulation of the negative co-stimulation receptors PD-1 or TIM-3 were observed. In all, our data identify expansion of dysfunctional CD56^neg NK cells in CMV⁺EBV⁺ elderly individuals suggesting that these cells may function as shape-shifters of cellular immunity and argue for a previously unrecognized role of EBV in mediating immune risk in the elderly.

Advances in cytomegalovirus (CMV) biology and its relationship to health, diseases, and aging

Cytomegalovirus (CMV) is one of the largest and most ubiquitous latent persistent viruses. Most humans are infected with CMV early in life, and all immunocompetent humans spend several decades living with CMV. In the vast majority of the hosts, CMV does not cause manifest disease, and CMV therefore can be considered part of normal aging for 50–90% of the human population worldwide. Experimental, clinical, and epidemiological studies suggest that CMV carriage can have nuanced outcomes, including both potentially harmful and potentially beneficial impacts on the host. We here present a summary of the 7th International Workshop on CMV and Immunosenescence, covering various aspects of the interplay between CMV and its mammalian hosts in the context of virus spread, immune evasion, antiviral immunity, as well as the impact on health span and aging.

Human Cytomegalovirus Infection in Women With Preexisting Immunity: Sources of Infection and Mechanisms of Infection in the Presence of Antiviral Immunity

Human cytomegalovirus (HCMV) infection remains an important cause of neurodevelopmental sequelae in infants infected in utero. Unique to the natural history of perinatal HCMV infections is the occurrence of congenital HCMV infections (cCMV) in women with existing immunity to HCMV, infections that have been designated as nonprimary maternal infection. In maternal populations with a high HCMV seroprevalence, cCMV that follows nonprimary maternal infections accounts for 75%-90% of all cases of cCMV infections as well as a large proportion of infected infants with neurodevelopmental sequelae. Although considerable effort has been directed toward understanding immune correlates that can modify maternal infections and intrauterine transmission, the source of virus leading to nonprimary maternal infections and intrauterine transmission is not well defined. Previous paradigms that included reactivation of latent virus as the source of infection in immune women have been challenged by studies demonstrating acquisition and transmission of antigenically distinct viruses, a finding suggesting that reinfection through exposure to an exogenous virus is responsible for some cases of nonprimary maternal infection. Additional understanding of the source(s) of virus that leads to nonprimary maternal infection will be of considerable value in the development and testing of interventions such as vaccines designed to limit the incidence of cCMV in populations with high HCMV seroprevalence.

Impact of Cytomegalovirus Disease on New-Onset Type 2 Diabetes Mellitus: Population-Based Matched Case-Control Cohort Study

BACKGROUND

A latent cytomegalovirus (CMV) cause chronic inflammation through undesirable inflation of cell-mediated immune response. CMV immunoglobulin G has been associated with cardiovascular disease and type 1 diabetes mellitus. We evaluated impact of CMV diseases on new-onset type 2 diabetes mellitus (T2DM).

METHODS

From the Korean Health Insurance Review and Assessment Service claim database of entire population with 50 million, we retrieved 576 adult case group with CMV diseases diagnosed with International Statistical Classification of Diseases and Related-Health Problems 10th Revision (ICD-10) B25 code between 2010 and 2014 after exclusion of patients with T2DM to 2006. The 2,880 control patients without T2DM from 2006 to cohort entry point were selected between 2010 and 2014 by age, sex matching with case group. The subjects without new-onset T2DM were followed until 2015. T2DM, hypertension (HTN), dyslipidemia (DYS), and end-stage renal disease (ESRD) were coded as ICD-10.

RESULTS

The frequency of new-onset T2DM in case group was significantly higher than that in control (5.6% vs. 2.2%, P<0.001). The group with T2DM (n=95) had higher incidence of CMV diseases than the group without T2DM (n=3,361) (33.7% vs. 16.2%, P<0.001). In multivariate regression model adjusted by age, sex, lower income, HTN, and DYS, the incidence rate (IR) of T2DM in case group was significantly higher than that in the control group (IR per 1,000, 19.0 vs. 7.3; odds ratio, 2.1; 95% confidence interval, 1.3 to 3.2). The co-existence of HTN, DYS, and ESRD with CMV diseases did not influence the IR of T2DM.

CONCLUSION

CMV diseases increase the patients' risk of developing T2DM.

The Current Status of Cytomegalovirus (CMV) Prevalence in the MENA Region: A Systematic Review

Human cytomegalovirus (CMV) is a highly prevalent herpesvirus worldwide. According to the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO), CMV infects people of all ages, and by the age of five, approximately one-third of children in the United States are infected. Although the infection is generally asymptomatic, it can cause severe disease in immunocompromised patients, transplant and transfusion recipients, as well as newborn neonates. The objective of this study is to systematically review published literature on CMV in the MENA region to estimate its incidence in the region and describe its epidemiological and clinical significance. The literature was searched through four scientific databases: PubMed, Scopus, Science Direct, and Web of Science. A total of 72 studies from 11 countries satisfied the inclusion criteria, covering a period from 1988-2019. The CMV IgG seroprevalence ranged from 8.7%-99.2% (SD = 38.95%). CMV incidence in these countries ranged between 1.22% and 77% in transplant and transfusion recipients, with an increase in incidence with advanced age. However, the incidence rate was unclear for congenital CMV due to the variability of the reporting. This review highlights the need for more robust and well-designed studies to better estimate CMV incidence in the MENA region, standardize diagnostic criteria, and consider prophylactic and pre-emptive treatments to limit the morbidity and mortality of the disease.

Immunosenescence and Its Hallmarks: How to Oppose Aging Strategically? A Review of Potential Options for Therapeutic Intervention

Aging is accompanied by remodeling of the immune system. With time, this leads to a decline in immune efficacy, resulting in increased vulnerability to infectious diseases, diminished responses to vaccination, and a susceptibility to age-related inflammatory diseases. An age-associated immune alteration, extensively reported in previous studies, is the reduction in the number of peripheral blood naïve cells, with a relative increase in the frequency of memory cells. These two alterations, together with inflamm-aging, are considered the hallmarks of immunosenescence. Because aging is a plastic process, it is influenced by both nutritional and pharmacological interventions. Therefore, the role of nutrition and of immunomodulation in immunosenescence is discussed, due to the multifactorial influence on these hallmarks. The close connection between nutrition, intake of bioactive nutrients and supplements, immune function, and inflammation demonstrate the key role of dietary strategies as regulators of immune response and inflammatory status, hence as possible modulators of the rate of immunosenescence. In addition, potential options for therapeutic intervention are clarified. In particular, the use of interleukin-7 as growth factor for naïve T cells, the function of checkpoint inhibitors in improving T cell responses during aging and, the potential of drugs that inhibit mitogen-activated protein kinases and their interaction with nutrient signaling pathways are discussed. Finally, it is suggested that the inclusion of appropriate combinations of toll-like receptor agonists may enhance the efficacy of vaccination in older adults.

Perceived stress, cytomegalovirus titers, and late-differentiated T and NK cells: Between-, within-person associations in a longitudinal study of older adults

Cytomegalovirus (CMV) and psychological stress are implicated as drivers of immunological aging. It is unknown, however, whether associations among CMV titers, stress, and immune aging are more stable or dynamic over time. The present investigation tested the between-person (stable differences) and within-person (dynamic fluctuations) associations of CMV titers and perceived stress on late-differentiated T and natural killer (NK) peripheral blood cells in a longitudinal study of older adults aged 64-92 years (N = 149). Participants reported stress levels and provided blood biannually for 2.5 years (up to 5 waves per person) to assess CMV IgG titers and composites of late-differentiated CD8 T cells (CD28- and CD57 + subsets) and CD56dim NK cells (CD57+, NKG2C+, and FcεRIγ- subsets). In multilevel models that controlled for demographic variables, higher CMV titers were associated with higher proportions and counts of aged T and NK cells between people and lower counts of aged T cells within people. Perceived stress was associated with higher counts of aged T cells between people, but was not associated with aged NK cells. A significant interaction between stress and CMV titers on T cells between people indicated that older adults with lower stress levels and lower CMV titers had the lowest proportions of late-differentiated T cells, whereas those with higher stress levels had high proportions, regardless of CMV control. Our results provide evidence for longer-term, between-person associations among CMV titers, stress, and immunological aging, rather than dynamic within-person associations. We propose that targeting factors that promote low, stable perceived stress in older adults may retard T cell differentiation and ultimately support healthy aging.

The Immune System and Its Dysregulation with Aging

Aging leads to numerous changes that affect all physiological systems of the body including the immune system, causing greater susceptibility to infectious disease and contributing to the cardiovascular, metabolic, autoimmune, and neurodegenerative diseases of aging. The immune system is itself also influenced by age-associated changes occurring in such physiological systems as the endocrine, nervous, digestive, cardio-vascular and muscle-skeletal systems. This chapter describes the multidimensional effects of aging on the most important components of the immune system. It considers the age-related changes in immune cells and molecules of innate and adaptive immunity and consequent impairments in their ability to communicate with each other and with their aged environment. The contribution of age-related dysregulation of hematopoiesis, required for continuous replenishment of immune cells throughout life, is discussed in this context, as is the developmentally-programmed phenomenon of thymic involution that limits the output of naïve T cells and markedly contributes to differences between younger and older people in the distribution of peripheral blood T-cell types. How all these changes may contribute to low-grade inflammation, sometimes dubbed "inflammaging", is considered. Due to findings implicating elevated inflammatory immuno-mediators in age-associated chronic autoimmune and neurodegenerative processes, evidence for their possible contribution to neuroinflammation is reviewed.

Role of age-related alterations of the cerebral venous circulation in the pathogenesis of vascular cognitive impairment

There has been an increasing appreciation of the role of vascular contributions to cognitive impairment and dementia (VCID) associated with old age. Strong preclinical and translational evidence links age-related dysfunction and structural alterations of the cerebral arteries, arterioles, and capillaries to the pathogenesis of many types of dementia in the elderly, including Alzheimer's disease. The low-pressure, low-velocity, and large-volume venous circulation of the brain also plays critical roles in the maintenance of homeostasis in the central nervous system. Despite its physiological importance, the role of age-related alterations of the brain venous circulation in the pathogenesis of vascular cognitive impairment and dementia is much less understood. This overview discusses the role of cerebral veins in the pathogenesis of VCID. Pathophysiological consequences of age-related dysregulation of the cerebral venous circulation are explored, including blood-brain barrier disruption, neuroinflammation, exacerbation of neurodegeneration, development of cerebral microhemorrhages of venous origin, altered production of cerebrospinal fluid, impaired function of the glymphatics system, dysregulation of cerebral blood flow, and ischemic neuronal dysfunction and damage. Understanding the age-related functional and phenotypic alterations of the cerebral venous circulation is critical for developing new preventive, diagnostic, and therapeutic approaches to preserve brain health in older individuals.

Role of Immunogenetics in the Outcome of HCMV Infection: Implications for Ageing

The outcome of host-virus interactions is determined by a number of factors, some related to the virus, others to the host, such as environmental factors and genetic factors. Therefore, different individuals vary in their relative susceptibility to infections. Human cytomegalovirus (HCMV) is an important pathogen from a clinical point of view, as it causes significant morbidity and mortality in immunosuppressed or immunosenescent individuals, such as the transplanted patients and the elderly, respectively. It is, therefore, important to understand the mechanisms of virus infection control. In this review, we discuss recent advances in the immunobiology of HCMV-host interactions, with particular emphasis on the immunogenetic aspects (human leukocyte antigens, HLA; killer cell immunoglobulin-like receptors, KIRs; immunoglobulin genetic markers, GM allotypes) to elucidate the mechanisms underlying the complex host-virus interaction that determine various outcomes of HCMV infection. The results, which show the role of humoral and cellular immunity in the control of infection by HCMV, would be valuable in directing efforts to reduce HCMV spurred health complications in the transplanted patients and in the elderly, including immunosenescence. In addition, concerning GM allotypes, it is intriguing that, in a Southern Italian population, alleles associated with the risk of developing HCMV symptomatic infection are negatively associated with longevity.

Subclinical Reactivation of Cytomegalovirus Drives CD4+CD28null T-Cell Expansion and Impaired Immune Response to Pneumococcal Vaccination in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

Background

Infection is the leading cause of death in antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Expansion of CD4+CD28null T cells is associated with increased risk of infection and mortality, but is only present in cytomegalovirus (CMV)-seropositive individuals. We hypothesized that subclinical CMV reactivation drives CD4+CD28null T-cell expansion, that this is associated with impaired immune response to heterologous antigens, and that antiviral therapy may ameliorate this.

Methods

In a proof-of-concept open-label clinical trial, 38 CMV-seropositive AAV patients were randomized to receive valacyclovir for 6 months or no intervention. CMV reactivation was measured monthly in plasma and urine. CD4+CD28null T cells were enumerated at baseline and at 6 months. At 6 months, 36 patients were vaccinated with a 13-valent pneumococcal vaccine. Serotype-specific immunoglobulin G was assayed before and 4 weeks postvaccination to calculate the antibody response ratio.

Results

Valacyclovir treatment suppressed subclinical CMV reactivation and reduced CD4+CD28null T-cell proportion. CD4+CD28null T-cell reduction correlated with improved vaccine response, whereas CMV reactivation associated with reduced response to vaccination. Furthermore, expansion of CD4+CD28null T cells was associated with a reduction in the functional capacity of the CD4 compartment.

Conclusions

Suppression of CMV may improve the immune response to a T-cell-dependent pneumococcal vaccination in patients with AAV, thus offering potential clinical benefit.

Clinical Trials Registration

NCT01633476.

Advances and challenges in geroscience research: An update

Aging remains the most pervasive risk factor for a wide range of chronic diseases that afflict modern societies. In the United States alone, incidence of age-related diseases (e.g., cardiovascular disease, stroke, Alzheimer's disease, vascular cognitive impairment and dementia, cancer, hypertension, type-2 diabetes, chronic obstructive pulmonary disease, and osteoarthritis) is on the rise, posing an unsustainable socioeconomic burden even for the most developed countries. Tackling each and every age-related disease alone is proving to be costly and ineffective. The emerging field of geroscience has posed itself as an interdisciplinary approach that aims to understand the relationship between the biology of aging and the pathophysiology of chronic age-related diseases. According to the geroscience concept, aging is the single major risk factor that underlies several age-related chronic diseases, and manipulation of cellular and systemic aging processes can delay the manifestation and/or severity of these age-related chronic pathologies. The goal of this endeavor is to achieve health improvements by preventing/delaying the pathogenesis of several age-related diseases simultaneously in the elderly population by targeting key cellular and molecular processes of aging instead of managing diseases of aging as they arise individually. In this review, we discuss recent advances in the field of geroscience, highlighting their implications for potential future therapeutic targets and the associated scientific challenges and opportunities that lay ahead.

Nrf2 deficiency in aged mice exacerbates cellular senescence promoting cerebrovascular inflammation

Aging-induced pro-inflammatory phenotypic alterations of the cerebral vasculature critically contribute to the pathogenesis of vascular cognitive impairment. Cellular senescence is a fundamental aging process that promotes inflammation; however, its role in cerebrovascular aging remains unexplored. The present study was undertaken to test the hypothesis that advanced aging promotes cellular senescence in the cerebral vasculature. We found that in cerebral arteries of 24-month-old mice, expression of molecular markers of senescence (p16^INK4a, p21) is upregulated as compared to that in young controls. Induction of senescence programs in cerebral arteries is associated by an upregulation of a wide range of inflammatory cytokines and chemokines, which are known to contribute to the senescence-associated secretory phenotype (SASP) in vascular cells. Age-related cerebrovascular senescence and inflammation are associated with neuroinflammation, as shown by the molecular footprint of microglia activation in the hippocampus. Genetic depletion of the pro-survival/anti-aging transcriptional regulator Nrf2 exacerbated age-related induction of senescence markers and inflammatory SASP factors and resulted in a heightened inflammatory status of the hippocampus. In conclusion, our studies provide evidence that aging and Nrf2 dysfunction promote cellular senescence in cerebral vessels, which may potentially cause or exacerbate age-related pathology.

Repeated Valsalva maneuvers promote symptomatic manifestations of cerebral microhemorrhages: implications for the pathogenesis of vascular cognitive impairment in older adults

Multifocal cerebral microhemorrhages (CMHs, also known as "cerebral microbleeds"), which are associated with rupture of small intracerebral vessels, have been recognized as an important cause for cognitive decline in older adults. Although recent studies demonstrate that CMHs are highly prevalent in patients 65 and older, many aspects of the pathogenesis and clinical significance of CMHs remain obscure. In this longitudinal observational study, a case of a 77-year-old man with multifocal CMHs is described, in whom the rupture of intracerebral vessels could be linked to repeatedly performing extended Valsalva maneuvers. This patient was initially seen with acute aphasia after performing a prolonged Valsalva maneuver during underwater swimming. T2-weighted magnetic resonance imaging revealed a left acute frontal intracerebral hemorrhage (ICH) with multiple CMHs. The aphasia was resolved and no cognitive impairment was present. Two years later, he developed unsteadiness and confusion after performing two prolonged Valsalva maneuvers during underwater swimming separated by about 12 days. Repeat brain imaging revealed an acute right and a subacute left ICH, with a marked interval increase in the number of CMHs. The patient also exhibited manifest memory loss after the second admission and was diagnosed with dementia. These observations suggest that prolonged Valsalva maneuver is potentially a common precipitating cause of both CMHs and symptomatic ICHs. The Valsalva maneuver both increases the systolic arterial pressure and gives rise to a venous pressure wave transmitted to the brain in the absence of the competent antireflux jugular vein valves. This pressure increase is superimposed on existing hypertension and/or increases in blood pressure due to exercise and increased venous return due to immersion of the body in water. We advocate that further studies are needed to distinguish between CMHs with arterial and venous origins and their potential to lead to ICH induced by Valsalva maneuver as well as to determine whether these lesions have a predilection for a particular location.

Altered CD4+ T cell immunity in nurses occupationally exposed to viral pathogens

Pathogen exposure, including but not limited to herpesviruses, moulds the shape of the immune system, both at a basal state and in response to immune challenge. However, little is known about the impact of high exposure to other viruses on baseline immune signatures and how the immune system copes with repetitive exposures to maintain a balanced functionality. Here we investigated baseline immune signatures, including detailed T cell phenotyping, antigen-specific CD4⁺ and CD8⁺ T cell responses and cytokine profile in paediatric (PED) nurses, who have high occupational exposure to viral pathogens including varicella zoster virus (VZV) and respiratory viruses, and in neonatal intensive care unit (NICU) nurses, as a control group with infrequent occupational exposure. Our results show a lower CD4⁺ T cell response to two VZV proteins (IE62 and gE) and to tetanus toxoid (TT) in PED nurses who are cytomegalovirus (CMV)-seronegative, compared to CMV-seronegative NICU nurses, and that the decline might be more pronounced the more sustained the exposure. This decline might be due to an attrition of VZV- and TT-specific T cells as a result of the continuous pressure on the CD4⁺ T cell compartment. Moreover, our data suggest that the distinct T cell phenotypes known to be associated with CMV-seropositivity might be less prominent in PED nurses compared to NICU nurses, implying a plausible attenuating effect of occupational exposure on CMV-associated immunosenescence. Overall, this pilot study reveals an impact of occupational exposure to viral pathogens on CD4⁺ T cell immunity and supports further investigation in a larger cohort.

Torquetenovirus (TTV) load is associated with mortality in Italian elderly subjects

An age-related dysregulation of immune response, known as immunosenescence, contributes to increased susceptibility to infections, frailty and high risk of mortality in the elderly. Torquetenovirus (TTV), a circular, single-stranded DNA virus, is highly prevalent in the general population and it may persist in the organism, also in association with other viruses such as cytomegalovirus (CMV), causing chronic viremia. The relationship that TTV establishes with the immune system of infected hosts is not clear. It is known that TTV encodes microRNAs (miRNAs) that might contribute to immune evasion and that the highest viral loads are found in peripheral blood cells. Moreover, it is suspected that TTV infection lead to increased production of inflammatory mediators, thus playing a role in immunosenescence. We investigated the association of TTV load and miRNAs expression with inflammatory and immune markers and the influence of TTV load on mortality within a cohort of 379 elderly subjects who were followed up for 3 years. TTV DNA load in polymorphonuclear leukocytes was slightly positively correlated with age and negatively associated with serum albumin levels and NK cell activity. A marginal positive correlation between TTV DNA load, monocytes and IL-8 plasma levels was found in females and males respectively. TTV DNA copies ≥4.0 log represented a strong predictor of mortality (Hazard ratio = 4.78, 95% CI: 1.70-13.44, after adjusting for age, sex and the main predictors of mortality rate) and this association remained significant even after the CMV IgG antibody titer was included in the model (HR = 9.83; 95% CI: 2.48-38.97; N = 343 subjects). Moreover, multiple linear regression model showed that TTV miRNA-t3b of genogroup 3 was inversely associated with triglycerides, monocytes and C-reactive protein, and directly associated with IL6. Overall these findings suggest a role of TTV in immunesenescence and in the prediction of all-cause mortality risk in Italian elderly subjects. Further studies are needed to fully understand the pathogenic mechanisms of TTV infection during aging.

Lifelong CMV infection improves immune defense in old mice by broadening the mobilized TCR repertoire against third-party infection

Lifelong interactions between host and the ubiquitous and persistent cytomegalovirus (CMV) have been proposed to contribute to the age-related decline in immunity. Prior work from us and others found some support for that idea, yet evidence that this led to increased vulnerability to other infections was not obtained. Moreover, evidence has accumulated that CMV infection can be beneficial to immune defense in young/adult mice and humans, dominantly via enhanced innate immunity. Here, we describe an unexpected impact of murine CMV (MCMV) upon the T cell response of old mice to Listeria monocytogenes expressing the model antigen, OVA (Lm-OVA). Single-cell sequencing of the OVA-specific CD8 T cell receptor β (TCRβ) repertoire of old mice demonstrated that old MCMV-infected mice recruited many diverse clonotypes that afforded broad and often more efficient recognition of antigenic peptide variants. This stood in contrast to old control mice, which exhibited strong narrowing and homogenization of the elicited repertoire. High-throughput sequencing of the total naïve CD8 TCRβ repertoire showed that many of these diverse OVA-specific clonotypes were present in the naïve CD8 repertoire of mice in all groups (adult, old control, and old MCMV⁺) yet were only recruited into the Lm-OVA response in MCMV⁺ old mice. These results have profound implications for our understanding of T cell immunity over a life span and suggest that our coevolution with CMV may include surprising, potentially positive impacts on adaptive heterologous immunity in late life.

Connective tissue growth factor (CTGF) in age-related vascular pathologies

Connective tissue growth factor (CTGF, also known as CCN2) is a matricellular protein expressed in the vascular wall, which regulates diverse cellular functions including cell adhesion, matrix production, structural remodeling, angiogenesis, and cell proliferation and differentiation. CTGF is principally regulated at the level of transcription and is induced by mechanical stresses and a number of cytokines and growth factors, including TGFβ. In this mini-review, the role of age-related dysregulation of CTGF signaling and its role in a range of macro- and microvascular pathologies, including pathogenesis of aorta aneurysms, atherogenesis, and diabetic retinopathy, are discussed. A potential role of CTGF and TGFβ in regulation and non-cell autonomous propagation of cellular senescence is also discussed.

Known unknowns: how might the persistent herpesvirome shape immunity and aging?

The microbial community that colonizes all living organisms is gaining appreciation for its contributions to both physiologic and pathogenic processes. The virome, a subset of the overall microbiome, large and diverse, including viruses that persistently inhabit host cells, endogenous viral elements genomically or epigenomically integrated into cells, and viruses that infect the other (bacterial, protozoan, fungal, and archaeal) microbiome phylla. These viruses live in the organism for its life, and therefore are to be considered part of the aging process experienced by the organism. This review considers the impact of the persistent latent virome on immune aging. Specific attention will be devoted to the role of herpesviruses, and within them, the cytomegalovirus, as the key modulators of immune aging.