Cytomegalovirus and Other β-Herpesviruses

Mechanism of herpesvirus UL24 protein regulating viral immune escape and virulence

Herpesviruses have evolved a series of abilities involved in the process of host infection that are conducive to virus survival and adaptation to the host, such as immune escape, latent infection, and induction of programmed cell death for sustainable infection. The herpesvirus gene UL24 encodes a highly conserved core protein that plays an important role in effective viral infection. The UL24 protein can inhibit the innate immune response of the host by acting on multiple immune signaling pathways during virus infection, and it also plays a key role in the proliferation and pathogenicity of the virus in the later stage of infection. This article reviews the mechanism by which the UL24 protein mediates herpesvirus immune escape and its effects on viral proliferation and virulence by influencing syncytial formation, DNA damage and the cell cycle. Reviewing these studies will enhance our understanding of the pathogenesis of herpesvirus infection and provide evidence for new strategies to combat against viral infection.

Disruption of thymic central tolerance by infection with murine roseolovirus induces autoimmune gastritis

Infections with herpesviruses, including human roseoloviruses, have been proposed to cause autoimmune disease, but defining a causal relationship and mechanism has been difficult due to the ubiquitous nature of infection and development of autoimmunity long after acute infection. Murine roseolovirus (MRV) is highly related to human roseoloviruses. Herein we show that neonatal MRV infection induced autoimmune gastritis (AIG) in adult mice in the absence of ongoing infection. MRV-induced AIG was dependent on replication during the neonatal period and was CD4+ T cell and IL-17 dependent. Moreover, neonatal MRV infection was associated with development of a wide array of autoantibodies in adult mice. Finally, neonatal MRV infection reduced medullary thymic epithelial cell numbers, thymic dendritic cell numbers, and thymic expression of AIRE and tissue-restricted antigens, in addition to increasing thymocyte apoptosis at the stage of negative selection. These findings strongly suggest that infection with a roseolovirus early in life results in disruption of central tolerance and development of autoimmune disease.

Integrative multiomics-histopathology analysis for breast cancer classification

Histopathologic evaluation of biopsy slides is a critical step in diagnosing and subtyping breast cancers. However, the connections between histology and multi-omics status have never been systematically explored or interpreted. We developed weakly supervised deep learning models over hematoxylin-and-eosin-stained slides to examine the relations between visual morphological signal, clinical subtyping, gene expression, and mutation status in breast cancer. We first designed fully automated models for tumor detection and pathology subtype classification, with the results validated in independent cohorts (area under the receiver operating characteristic curve ≥ 0.950). Using only visual information, our models achieved strong predictive performance in estrogen/progesterone/HER2 receptor status, PAM50 status, and TP53 mutation status. We demonstrated that these models learned lymphocyte-specific morphological signals to identify estrogen receptor status. Examination of the PAM50 cohort revealed a subset of PAM50 genes whose expression reflects cancer morphology. This work demonstrates the utility of deep learning-based image models in both clinical and research regimes, through its ability to uncover connections between visual morphology and genetic statuses.

Human Herpesvirus and the Immune Checkpoint PD-1/PD-L1 Pathway: Disorders and Strategies for Survival

The immune system has evolved as a complex and efficient means of coping with extrinsic materials, such as pathogens and toxins, as well as intrinsic abnormalities, such as cancers. Although rapid and timely activation of the immune system is obviously important, regulated downregulation of the system is almost as significant as activation to prevent runaway immunity, such as allergies and hypercytokinemia. Therefore, the immune checkpoint programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway is beneficial for the host. On the other hand, pathogens have evolved to evade host immunity by taking advantage of the PD-1/PD-L1 pathway. This review is focused on human herpesviruses, such as herpes simplex virus (HSV), cytomegalovirus (CMV), and Epstein-Barr virus (EBV), which cause various types of disorders, and their relationships with the PD-1/PD-L1 pathway. Understanding such relationships will be useful for developing preventative and therapeutic methods for disorders caused by herpesviruses.

A Novel 2-dimensional Multiplex qPCR Assay for Single-Tube Detection of Nine Human Herpesviruses

Human herpesviruses are double-stranded DNA viruses that are classified into nine species. More than 90% of adults are ever infected with one or more herpesviruses. The symptoms of infection with different herpesviruses are diverse ranging from mild or asymptomatic infections to deadly diseases such as aggressive lymphomas and sarcomas. Timely and accurate detection of herpesvirus infection is critical for clinical management and treatment. In this study, we established a single-tube nonuple qPCR assay for detection of all nine herpesviruses using a 2-D multiplex qPCR method with a house-keeping gene as the internal control. The novel assay can detect and distinguish different herpesviruses with 30 to 300 copies per 25 µL single-tube reaction, and does not cross-react with 20 other human viruses, including DNA and RNA viruses. The robustness of the novel assay was evaluated using 170 clinical samples. The novel assay showed a high consistency (100%) with the single qPCR assay for HHVs detection. The features of simple, rapid, high sensitivity, specificity, and low cost make this assay a high potential to be widely used in clinical diagnosis and patient treatment.

Longitudinal study on oral shedding of human betaherpesviruses 6 and 7 in renal transplant recipients reveals active replication

BACKGROUNG

Roseolovirus latency and persistence in salivary glands that are frequently reactivated after renal transplantation to cause infection have been reported. However, limited information is available on the persistence and excretion of HHV-6 and HHV-7 during and after transplant.

METHODS

32 renal transplant recipients were followed up before (T1) and after transplant (T2 and T3) and viral replication (via assessment of mRNA) in oral fluid samples investigated. Roseolovirus DNA was detected and quantified via multiplex qPCR. For evaluation of mRNA replication, positive samples were subjected to nested RT-PCR.

RESULTS

Viral replication of HHV-7 was significantly increased during T3 (72.9%), compared to the pre-transplant period T1 (25%; McNemar Test, p= 0.001). Analysis of the viral replicative to quantitative ratio disclosed ahigher number of DNA copies (>106) in positive cases of replication (p < 0.001). Astrong positive correlation (Spearman correlation coefficient = 0.781; p< 0.001) was evident between viral quantities of Roseoloviruses.

CONCLUSION

Our findings consistently suggest that the salivary gland is an important site of active and persistent infection by roseoloviruses. In view of the increasing problem of Roseoloviruses, pre- and post-transplantation, viral surveillance and monitoring of active replication are pivotal steps for effective screening and treatment of renal transplant patients.

Structural basis for membrane anchoring and fusion regulation of the herpes simplex virus fusogen gB

Viral fusogens merge viral and cell membranes during cell penetration. Their ectodomains drive fusion by undergoing large-scale refolding, but little is known about the functionally important regions located within or near the membrane. Here, we report the crystal structure of the full-length glycoprotein B, the fusogen from Herpes Simplex Virus, complemented by electron spin resonance measurements. The membrane-proximal (MPR), transmembrane (TMD), and cytoplasmic (CTD) domains form a uniquely folded trimeric pedestal beneath the ectodomain, which balances dynamic flexibility with extensive, stabilizing membrane interactions. Hyperfusogenic mutations within the CTD destabilize it, targeting trimeric interfaces, structural motifs, and membrane-interacting elements. Thus, we propose that the CTD trimer observed in the structure stabilizes gB in its prefusion state despite being appended to the postfusion ectodomain. Our data suggest a model for how this dynamic, membrane-dependent “clamp” controls the fusogenic refolding of gB.