Search Results (406)

Human cytomegalovirus (HCMV) establishes lifelong latency in the host, with the bone marrow (BM) CD34+ cells serving as a key reservoir. To investigate tissue-specific immune responses to CMV, we analysed paired peripheral blood mononuclear cells (PBMCs) and bone marrow mononuclear cells (BMMNCs) from HCMV-seropositive donors using multiparametric flow cytometry and cytokine FluroSpot assays. We assessed immune cell composition, memory T cell subsets, cytokine production, cytotoxic potential, activation marker expression, and checkpoint inhibitory receptor (CIR) profiles, both ex vivo and following stimulation with lytic and latent HCMV antigens. BMMNCs were enriched in CD34+ progenitor cells and exhibited distinct T cell memory subset distributions. HCMV-specific responses were compartmentalised: IFN-γ responses predominated in PBMCs following lytic antigen stimulation, while IL-10 and TNF-α responses were more prominent in BMMNCs, particularly in response to latent antigens. US28-specific T cells in the BM showed elevated expression of CD39, PD-1, BTLA, CTLA-4, ICOS, and LAG-3 on CD4+ T cells and increased expression of PD-1, CD39, BTLA, TIGIT, LAG-3, and ICOS on CD8+ T cell populations, suggesting a more immunoregulatory phenotype. These findings highlight functional and phenotypic differences in HCMV-specific T cell responses between blood and bone marrow, underscoring the role of the BM niche in shaping antiviral immunity and maintaining viral latency. Full article

Background: Human cytomegalovirus (HCMV) is the leading cause of congenital and acquired viral infections in newborns. While acquired infections are often asymptomatic, premature infants—especially those born before 30 weeks of gestation or with a very low birth weight (<1500 g)—are at an increased risk for severe infections. These can manifest as thrombocytopenia, liver failure, sepsis-like symptoms, and, in rare cases, death. HCMV is transmitted through various human secretions, including breast milk, which is the optimal feeding method for premature infants. Methods: We present five premature neonates, born between 23 and 26 weeks of gestation, each with a distinct clinical presentation of acquired HCMV infection. Results: All infants tested negative for congenital CMV infection via molecular urine testing within the first three weeks of life. Acquired infection was diagnosed between the second and third month of life, with symptoms such as septic shock, persistent thrombocytopenia, and signs of liver failure. Each infant received antiviral treatment along with regular viral load monitoring. Unfortunately, one patient died due to complications of prematurity. The remaining infants were discharged and continue to receive follow-up care in an outpatient clinic. Conclusions: These cases of postnatally acquired CMV infection aim to increase awareness of its highly heterogeneous and nonspecific clinical presentation, which may result in an incorrect, delayed, or concealed diagnosis. Currently, there are no clear guidelines on how to manage the presence of the virus in maternal breast milk, particularly for premature infants. It should be recommended to perform a molecular CMV test in all breast-fed preterm infants who present with sepsis-like symptoms, thrombocytopenia, liver failure, or other organ involvement. In case of a confirmed aCMV diagnosis, appropriate treatment should be introduced. Full article

Human cytomegalovirus (HCMV), a globally ubiquitous herpesvirus with the ability to carry out both lytic productive and lifelong latent infections, is a major cause of congenital infections, often leading to intellectual disabilities and neurological disorders. Moreover, HCMV is an opportunistic pathogen commonly found in immunocompromised individuals such as organ transplant recipients, HIV-positive individuals, and cancer patients, causing severe and life-threatening complications. While effective in inhibiting viral lytic infection, current FDA-approved compounds cannot eliminate the latent viral genome and have little effect on viral latent infection. Developing novel antiviral therapeutic approaches to eliminate HCMV lytic and latent infections is a major public health priority for controlling HCMV infection and preventing viral-associated diseases. The genome-editing technology based on the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated protein (Cas) RNA-guided nuclease system represents a novel and promising antiviral approach through modifying or destroying the genetic material of human viruses. This review summarizes the recently published progress in using the CRISPR-Cas approach to study and inhibit HCMV infections and discusses prospects for developing the CRISPR-based genome-editing technology for therapeutic applications against HCMV infection and associated diseases. Full article

Human cytomegalovirus (HCMV) is a ubiquitous member of the herpesvirus family, of significant clinical importance, and highly adapted to its host, resulting from millions of years of co-evolution. As a result, the virus systematically subverts almost all aspects of antiviral immune defence to successfully establish a lifelong persistent infection, and in the process, dramatically reshapes the phenotype and function of host immunity to both HCMV and other diseases. Natural killer (NK) cells are a critical component of successful herpesvirus control. Here, we discuss their role in modulating HCMV disease and the multitude of ways that HCMV has evolved to prevent and manipulate this process. We also consider how antibody-dependent cellular cytotoxicity by NK cells directed against HCMV might overcome NK immune evasion mechanisms and be useful therapeutically. Full article

Human cytomegalovirus (HCMV) coinfection is associated with a faster HIV disease progression and adverse clinical outcomes. HCMV-encoded miRNA expression, in individuals acutely infected with HIV (AHI), compared to those with HCMV monoinfection, was investigated in relation to viral replication and inflammation/immune activation. Sixteen individuals with AHI coinfected with HCMV were analyzed at serodiagnosis (T0) and after 6 (T1) and 12 (T2) months of antiretroviral therapy initiated within one week from serodiagnosis. Fourteen HCMV monoinfected subjects were also studied. Plasma RNA was reverse-transcribed and amplified with a panel designed to detect 14 different HCMV-microRNAs (miRNAs). VEGF-A and IP-10 plasma levels were quantified using ELISA. Except for hcmv-miR-70-3p, detected in all subjects, hcmv-miR-UL112-3p, hcmv-miR-US25-1-5p, hcmv-miR-US25-2-3p, hcmv-miR-US4-5p, hcmv-miR-US5-1, hcmv-miR-US5-2-3p, hcmv-miR-UL36-3p, and hcmv-miR-UL36-5p were significantly more frequently detected when HCMV DNA was present (lytic infection). In latent HCMV infection, hcmv-miR-UL22A-5p and hcmv-miR-UL148D were more frequently observed in HIV/HCMV-coinfected individuals, compared to mono-HCMV infection. Hcmv-miR-UL22A-5p and hcmv-miR-US33-5p showed a direct correlation with HIV-1 RNA. Notable positive correlations between hcmv-miR-UL22A-5p and the interferon-gamma-inducible protein 10 (IP-10), as well as between hcmv-miR-UL148D and the vascular endothelial growth factor A (VEGF-A), were also observed. HCMV-miRNA expression varies between lytic and latent infection and differs in HIV coinfection. In HCMV/HIV coinfection, increased levels of hcmv-miR-UL148D, associated with VEGF-A production, seem to be less linked to HIV viremia with respect to hcmv-miR-UL22A-5p and hcmv-miR-US33-5p. A deeper understanding of HCMV-encoded miRNA biology may facilitate the comprehension of HCMV/HIV coinfection pathogenetic mechanisms. Full article

Background/Objectives: A preventative vaccine against human cytomegalovirus (HCMV) infection and disease remains an unmet medical need. Several attenuated virus and antigen-based HCMV vaccine candidates have been proposed; however, development challenges have limited their progression through the clinical pipeline. Method: A high-throughput and robust relative potency assay, Imaging of Relative Viral Expression (IRVE), was developed and applied to measure the infection of a live-attenuated HCMV vaccine candidate in ARPE-19 epithelial cells. The IRVE assay measures HCMV infection by immunostaining Immediate Early 1 (IE1) protein and enumeration of IE1-positive, infected cells against total cells. Increased throughput was accomplished using 384-well plate automation on a custom-designed integrated robotic system. Results: The IRVE assay effectively measures relative potency changes in an HCMV vaccine candidate under different upstream processes, downstream processes, and formulation conditions. Key assay parameters including microplate format, cell density, serum concentration, infection time and influence of cell age were evaluated and optimized. The IRVE assay was correlated to historical, lower throughput HCMV potency assays, including plaque and Infectivity of Early Gene Expression (IEE), validating its application as a potency screening tool. Conclusions: The IRVE assay has been successfully implemented to support HCMV vaccine development over several years of clinical development. Full article

All beta- and gamma-herpesviruses utilize a set of six viral proteins to facilitate transcription from specific promoters that become active late in the viral life cycle. These proteins form a complex that interacts with a TA-rich sequence upstream of the late transcription start sites and recruits RNA polymerase II (Pol II). The structure of any of the late transcription factors (LTFs) alone or in complexes has not been solved by standard means yet, but a fair amount is known about how the proteins interact and where the complex is positioned over the late promoters. Here, AlphaFold3 was used to predict and analyze the LTF complex using proteins from the beta-herpesviruses HCMV, MCMV, HHV6, and HHV7, and from the gamma-herpesviruses EBV and KSHV. The predicted structures had high levels of confidence and were remarkably similar even though there is little sequence conservation in the LTFs across the viruses. The results are consistent with most of the previously determined information concerning the interaction of the factors with each other and with DNA. A conserved threonine phosphorylation in one of the subunits that is critical to the function of the LTFs is predicted to be at the junction of five subunits. AlphaFold 3 predicts seven metal ion binding sites in each of the four beta-herpesviruses and either five or six in the gamma-herpesviruses created by conserved residues in three of the subunits. The structures also provide insights into the function of the subunits and which host general transcription factors (GTFs) may or may not be utilized during initiation. Full article

Human cytomegalovirus (HCMV) infection during pregnancy is a leading cause of congenital infections worldwide, posing significant risks to fetal health. Despite advances in prenatal care, managing HCMV infection remains challenging. Early detection, accurate risk assessment, and timely intervention are critical to mitigating the adverse outcomes associated with congenital HCMV (cHCMV), such as neurodevelopmental delays and hearing loss. However, the current landscape of biomarkers for HCMV infection in pregnancy is marked by several unmet needs. These gaps in biomarker development and application limit our ability to predict fetal transmission, assess the risk of fetal damage, and prognosticate long-term outcomes. Addressing these challenges through the identification and validation of novel biomarkers could revolutionize the management of HCMV in pregnancy, leading to improved outcomes for both mothers and their children. This review examines the critical unmet needs regarding HCMV biomarkers during pregnancy, emphasizing the priority areas for further research and innovation. Full article

Periodontal disease (PD) is an inflammatory condition that can contribute to the development of oral cancer. Chronic inflammation from PD can lead to the release of inflammatory mediators and growth factors that promote tumorigenesis. Porphyromonas gingivalis (P. gingivalis) is one of several pathogens implicated in PD and its potential link to oral cancer. However, other viral infections, such as human cytomegalovirus (HCMV), can also contribute to chronic inflammation, creating a favorable environment for oral cancer development. Objectives: The present literature review tries to investigate the possible influence of P. gingivalis and HCMV co-infection in fostering the development of oral cancer and chronic periodontitis. Methods: A comprehensive search was conducted in PubMed and Google Scholar, focusing on the relevance and significance of articles that examine the role of P. gingivalis and HCMV in periodontal disease and oral cancer. Results: The evidence suggests that P. gingivalis and HCMV may act synergistically to modulate host immunity, disrupt epithelial integrity, and interfere with key cellular pathways. These interactions may enhance tissue destruction and foster a microenvironment conducive to malignant transformation. However, most of these findings stem from in vitro models and small-scale clinical studies, limiting the generalizability and clinical relevance of current conclusions. Conclusions: Although the proposed interaction between P. gingivalis and HCMV provides a compelling framework for understanding how microbial co-infections may influence oral cancer, the evidence remains preliminary and largely associative. To support these mechanistic hypotheses, future studies should give top priority to in vivo models, bigger patient cohorts, and longitudinal clinical studies. Full article

Human cytomegalovirus (HCMV) is a critical pathogen in immunocompromised populations, such as organ transplant recipients as well as congenitally infected neonates with immature immune systems. Despite decades of research and the growing financial burden associated with the management of HCMV, there is no licensed vaccine to date. In this review, we aim to outline the complexity of HCMV and the antigens it presents and the journey and challenges of developing an effective HCMV vaccine, as well as further highlight the recent analyses of the most successful vaccine candidate so far—gB/MF59. Full article

Human cytomegalovirus (HCMV) is a high-risk pathogen in immunocompromised individuals, especially in transplant recipients. HCMV viremia must be monitored, and frequently, patients are treated with antiviral agents. HCMV has a variety of strategies to modulate host antiviral responses, and one important player is a viral homolog of the cellular interleukin-10 (cIL-10). The viral UL111A gene produces several HCMV IL-10 transcripts and protein isoforms through alternative splicing. The cmvIL-10 (isoform A) has similar properties to cIL-10, while LAcmvIL-10 (isoform B) has more restricted biological properties. Other isoforms are produced (C to H) but have unknown functions. Here, we investigated the expression of the most abundant transcripts, cmvIL-10 and LAcmvIL-10, in productively and latently infected cells and in peripheral blood mononuclear cells from renal transplant recipients up to 60 days post-transplantation. This study investigated HCMV cmvIL-10 and LAcmvIL-10 transcription profiles in vitro, in productive and latent infection, and in vivo, in peripheral blood mononuclear cells (PBMCs) of renal transplant patients. In vitro, both cmvIL-10 and LAcmvIL-10 transcripts were detected in both types at high levels and low levels in MRC-5 and latent infected (CD14+). When PBMCs from transplant patients were analyzed, LAcmvIL-10 was detected mostly sporadically and in only a few patients, while cmvIL-10 was found in all patients at all time points. Furthermore, it was observed in PBMCs that expression of cmvIL-10 was positively associated with an increase in viral DNA detection in the subsequently collected sample, indicating that expression of cmvIL-10 might precede viral DNA replication. These results contribute to the understanding of HCMV biology in different phases of infection. In addition, our initial analysis suggests that monitoring cmvIL-10, along with viral DNA, could improve early detection of HCMV reactivation in transplant recipients. Full article

Over the past three decades, immunodeficient mouse models carrying human immune cells, with or without human lymphoid tissues, termed humanized immune system (HIS) rodent models, have been developed to recapitulate the human immune system and associated immune responses. HIS mouse models have successfully modeled many human-restricted viral infections, including those caused by human cytomegalovirus (HCMV) and human immunodeficiency virus (HIV). HIS mouse models have also been used to model human cancer immunobiology, which exhibits differences from murine cancers in traditional mouse models. Variants of HIS mouse models that carry human liver cells, lung tissue, skin tissue, or human patient-derived tumor xenografts and human hematopoietic stem cells-derived-human immune cells with or without lymphoid tissue xenografts have been developed to probe human immune responses to infections and human tumors. HCMV-based vaccines are human-restricted, which poses limitations for mechanistic and efficacy studies using traditional animal models. The HCMV-based vaccine approach is a promising vaccine strategy as it induces robust effector memory T cell responses that may be critical in preventing and rapidly controlling persistent viral infections and cancers. Here, we review novel HIS mouse models with robust human immune cell development and primary and secondary lymphoid tissues that could address many of the limitations of HIS mice in their use as animal models for HCMV-based vaccine research. We also reviewed novel HIS rat models, which could allow long-term (greater than one year) vaccinology studies and better recapitulate human pathophysiology. Translating laboratory research findings to clinical application is a significant bottleneck in vaccine development; HIS rodents and related variants that more accurately model human immunology and diseases could increase the translatability of research findings. Full article

Leukemia is a hematologic malignancy; acute lymphoblastic leukemia (ALL) is the most prevalent subtype among children rather than in adults. Orthoherpesviridae family members produce proteins during latent infection phases that may contribute to cancer development. One such protein, viral interleukin-10 (vIL-10), closely resembles human interleukin-10 (IL-10) in structure. Research has explored the involvement of human cytomegalovirus (hCMV) in the pathogenesis of ALL. However, the limited characterization of its latent-phase proteins restricts a full understanding of the relationship between hCMV infection and leukemia progression. Studies have shown that hCMV induces an inflammatory response during infection, marked by the release of cytokines and chemokines. Inflammation may, therefore, play a role in how hCMV contributes to oncogenesis in pediatric ALL, possibly mediated by latent viral proteins. The classification of a virus as oncogenic is based on its alignment with cancer’s established hallmarks. Viruses can manipulate host cellular mechanisms, causing dysregulated cell proliferation, evasion of apoptosis, and genomic instability. These processes lead to mutations, chromosomal abnormalities, and chronic inflammation, all of which are vital for carcinogenesis. This study aims to investigate the role of vIL-10 during the latent phase of hCMV as a potential factor in leukemia development. Full article

Infection of cells with the human cytomegalovirus (HCMV) triggers the expression of interferon-stimulated genes (ISGs). ISGs encode proteins with antiviral functions, such as inhibiting viral replication, promoting cell death of infected cells and enhancing immune responses. HCMV has evolved mechanisms to evade the antiviral effects of ISGs. The viral proteins encoded by the viral genes US7, US8, and US9 have been shown to interfere with interferon induction. US7 to US9 are embedded in a cluster of HCMV genes, termed US2 to US11. The individual members of this gene family interfere on multiple levels with innate and adaptive immune responses to HCMV infection. Using viral mutants with different deletions in US2 to US11, we addressed the question if genes other than US7 to US9 would also influence the IFN responses. Surprisingly, deletion of the complete US2 to US11 gene region led to reduced levels of selected ISGs. Cells infected with viruses in which individual US2 to US11 genes were deleted showed a less pronounced reduction of the selected ISGs. The experiments including RNA-seq analyses indicate that genes of the US2 to US11 gene family have a complex interaction with the IFN-ISG response which is likely regulated on the level of ISG protein stability. As US2–US11 are dispensable for replication in cell culture, the genomic region was frequently used for the insertion of bacterial artificial chromosome vectors in the process of cloning the complete HCMV genome. The results shown here must be considered when viruses derived from BACs with US2–US11 deletions are used and whether appropriate controls must be applied. Full article

An exhausted antiviral immune response is observed in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and post-SARS-CoV-2 syndrome, also termed long COVID. In this study, potential mechanisms behind this exhaustion were investigated. First, the viral load of Epstein–Barr virus (EBV), human adenovirus (HAdV), human cytomegalovirus (HCMV), human herpesvirus 6 (HHV6), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was determined in sputum samples (n = 29) derived from ME/CFS patients (n = 13), healthy controls (n = 10), elderly healthy controls (n = 4), and immunosuppressed controls (n = 2). Secondly, autoantibodies (autoAbs) to type I interferon (IFN-I) in sputum were analyzed to possibly explain impaired viral immunity. We found that ME/CFS patients released EBV at a significantly higher level compared to controls (p = 0.0256). HHV6 was present in ~50% of all participants at the same level. HAdV was detected in two cases with immunosuppression and severe ME/CFS, respectively. HCMV and SARS-CoV-2 were found only in immunosuppressed controls. Notably, anti-IFN-I autoAbs in ME/CFS and controls did not differ, except in a severe ME/CFS case showing an increased level. We conclude that ME/CFS patients, compared to controls, have a significantly higher load of EBV. IFN-I autoAbs cannot explain IFN-I dysfunction, with the possible exception of severe cases, also reported in severe SARS-CoV-2. We forward that additional mechanisms, such as the viral evasion of IFN-I effect via the degradation of IFN-receptors, may be present in ME/CFS, which demands further studies. Full article