Human complement receptor type 1/CD35 is an Epstein-Barr Virus receptor. Cell Rep. 2013;3:371-385. [PMID: 23416052 DOI: 10.1016/j.celrep.2013.01.023]

EBV-positive glycoproteins associated with nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is closely related to Epstein-Barr virus (EBV) infection, and glycosylation of proteins is associated with precancerous lesions and carcinogenesis of NPC, and viral glycoproteins mediates the fusion of viruses with B cells or epithelial cells in the infection stage, promoting the conversion of normal epithelial cells into cancer cells. In the process of occurrence and development of NPC, various glycoproteins in the body promote or inhibit the proliferation, invasion, metastasis, and drug resistance of tumor cells, such as the tumor inhibitory effect of NGX6 and inhibin B (INHBB); the cancer-promoting effect of tenascin-C (TNC), fibronectin 1 (FN1), insulin-like growth factor binding protein-3 (IGFBP3), serglycin, and its core protein; and some effects of glycosylation of immune proteins on immunotherapy in NPC. This article provides an overview of the research progress on the interaction of glycoproteins associated with EBV infection with the occurrence and development of NPC.

The Interactions of the Complement System with Human Cytomegalovirus

The complement system is an evolutionarily ancient component of innate immunity that serves as an important first line of defense against pathogens, including viruses. In response to infection, the complement system can be activated by three distinct yet converging pathways (classical, lectin, and alternative) capable of engaging multiple antiviral host responses to confront acute, chronic, and recurrent viral infections. Complement can exert profound antiviral effects via multiple mechanisms including the induction of inflammation and chemotaxis to sites of infection, neutralization/opsonization of viruses and virally infected cells, and it can even shape adaptive immune responses. With millions of years of co-evolution and the ability to establish life-long infections, herpesviruses have evolved unique mechanisms to counter complement-mediated antiviral defenses, thus enabling their survival and replication within humans. This review aims to comprehensively summarize how human herpesviruses engage with the complement system and highlight our understanding of the role of complement in human cytomegalovirus (HCMV) infection, immunity, and viral replication. Herein we describe the novel and unorthodox roles of complement proteins beyond their roles in innate immunity and discuss gaps in knowledge and future directions of complement and HCMV research.

GB and gH/gL fusion machinery: a promising target for vaccines to prevent Epstein-Barr virus infection

Epstein‒Barr virus (EBV) is a double-stranded DNA virus belonging to the family Orthoherpesviridae that is associated with the development of various tumors, such as lymphoma, nasopharyngeal carcinoma, and gastric cancer. There are no uniformly effective treatments for human EBV infection, and vaccines and immunotherapies are currently the main research directions. The glycoproteins gB and gH/gL are surface glycoproteins that are common to all herpesviruses, with subtle differences in structure and function between different viruses. The core membrane fusion machinery constituted by EBV gB and gH/gL is an important target of neutralizing antibodies in epithelial EBV infection due to its essential role in the fusion of viral and target cell membranes. In this article, we review the main modes of EBV infection, the structure and function of the core fusion machinery gB and gH/gL, and the development of neutralizing antibodies and prophylactic vaccines based on this target.

Analyzing the Impact of the Highest Expressed Epstein-Barr Virus-Encoded microRNAs on the Host Cell Transcriptome

The Epstein-Barr virus (EBV) has a very high prevalence (>90% in adults), establishes a lifelong latency after primary infection, and exerts an oncogenic potential. This dsDNA virus encodes for various molecules, including microRNAs (miRs), which can be detected in the latent and lytic phases with different expression levels and affect, among others, immune evasion and malignant transformation. In this study, the different EBV miRs are quantified in EBV-positive lymphomas, and the impact on the host cell transcriptome of the most abundant EBV miRs will be analyzed using comparative RNA sequencing analyses. The EBV miRs ebv-miR-BART1, -BART4, -BART17, and -BHRF1-1 were most highly expressed, and their selective overexpression in EBV-negative human cells resulted in a large number of statistically significantly down- and up-regulated host cell genes. Functional analyses showed that these dysregulated target genes are involved in important cellular processes, including growth factor pathways such as WNT, EGF, FGF, and PDGF, as well as cellular processes such as apoptosis regulation and inflammation. Individual differences were observed between these four analyzed EBV miRs. In particular, ebv-miR-BHRF1-1 appears to be more important for malignant transformation and immune evasion than the other EBV miRs.

A gH/gL-encoding replicon vaccine elicits neutralizing antibodies that protect humanized mice against EBV challenge

Epstein-Barr virus (EBV) is associated with several malignancies, neurodegenerative disorders and is the causative agent of infectious mononucleosis. A vaccine that prevents EBV-driven morbidity and mortality remains an unmet need. EBV is orally transmitted, infecting both B cells and epithelial cells. Several virally encoded proteins are involved in entry. The gH/gL glycoprotein complex is essential for infectivity irrespective of cell type, while gp42 is essential for infection of B cells. gp350 promotes viral attachment by binding to CD21 or CD35 and is the most abundant glycoprotein on the virion. gH/gL, gp42 and gp350, are known targets of neutralizing antibodies and therefore relevant immunogens for vaccine development. Here, we developed and optimized the delivery of several alphavirus-derived replicon RNA (repRNA) vaccine candidates encoding gH/gL, gH/gL/gp42 or gp350 delivered by a cationic nanocarrier termed LION™. The lead candidate, encoding full-length gH/gL, elicited high titers of neutralizing antibodies that persisted for at least 8 months and a vaccine-specific CD8+ T cell response. Transfer of vaccine-elicited IgG protected humanized mice from EBV-driven tumor formation and death following high-dose viral challenge. These data demonstrate that LION/repRNA-gH/gL is an ideal candidate vaccine for preventing EBV infection and/or related malignancies in humans.

A comprehensive review on targeting cluster of differentiation: An attractive strategy for inhibiting viruses through host proteins

Viral infections continue to pose a significant global public health threat. Targeting host proteins, such as cluster of differentiation (CD) macromolecules, may offer a promising alternative approach to developing antiviral treatments. CDs are cell-surface biological macromolecules mainly expressed on leukocytes that viruses can use to enter cells, thereby evading immune detection and promoting their replication. The manipulation of CDs by viruses may represent an effective and clever means of survival through the prolonged co-evolution of hosts and viruses. Targeting of CDs is anticipated to hinder the invasion of related viruses, modulate the body's immune system, and diminish the incidence of subsequent inflammation. They have become crucial for biomedical diagnosis, and some have been used as valuable tools for resisting viral infections. However, a summary of the structures and functions of CDs involved in viral infection is currently lacking. The development of drugs targeting these biological macromolecules is restricted both in terms of their availability and the number of compounds currently identified. This review provides a comprehensive analysis of the critical role of CD proteins in virus invasion and a list of relevant targeted antiviral agents, which will serve as a valuable reference for future research in this field.

CHO cells for virus-like particle and subunit vaccine manufacturing

Chinese Hamster Ovary (CHO) cells, employed primarily for manufacturing monoclonal antibodies and other recombinant protein (r-protein) therapeutics, are emerging as a promising host for vaccine antigen production. This is exemplified by the recently approved CHO cell-derived subunit vaccines (SUV) against respiratory syncytial virus (RSV) and varicella-zoster virus (VZV), as well as the enveloped virus-like particle (eVLP) vaccine against hepatitis B virus (HBV). Here, we summarize the design, production, and immunogenicity features of these vaccine and review the most recent progress of other CHO-derived vaccines in pre-clinical and clinical development. We also discuss the challenges associated with vaccine production in CHO cells, with a focus on ensuring viral clearance for eVLP products.

Update of Natural Products and Their Derivatives Targeting Epstein-Barr Infection

Epstein-Barr (EBV) is a human γ-herpesvirus that undergoes both a productive (lytic) cycle and a non-productive (latent) phase. The virus establishes enduring latent infection in B lymphocytes and productive infection in the oral mucosal epithelium. Like other herpesviruses, EBV expresses its genes in a coordinated pattern during acute infection. Unlike others, it replicates its DNA during latency to maintain the viral genome in an expanding pool of B lymphocytes, which are stimulated to divide upon infection. The reactivation from the latent state is associated with a productive gene expression pattern mediated by virus-encoded transcriptional activators BZLF-1 and BRLF-1. EBV is a highly transforming virus that contributes to the development of human lymphomas. Though viral vectors and mRNA platforms have been used to develop an EBV prophylactic vaccine, currently, there are no vaccines or antiviral drugs for the prophylaxis or treatment of EBV infection and EBV-associated cancers. Natural products and bioactive compounds are widely studied for their antiviral potential and capability to modulate intracellular signaling pathways. This review was intended to collect information on plant-derived products showing their antiviral activity against EBV and evaluate their feasibility as an alternative or adjuvant therapy against EBV infections and correlated oncogenesis in humans.

Non-overlapping epitopes on the gHgL-gp42 complex for the rational design of a triple-antibody cocktail against EBV infection

Epstein-Barr virus (EBV) is closely associated with cancer, multiple sclerosis, and post-acute coronavirus disease 2019 (COVID-19) sequelae. There are currently no approved therapeutics or vaccines against EBV. It is noteworthy that combining multiple EBV glycoproteins can elicit potent neutralizing antibodies (nAbs) against viral infection, suggesting possible synergistic effects. Here, we characterize three nAbs (anti-gp42 5E3, anti-gHgL 6H2, and anti-gHgL 10E4) targeting different glycoproteins of the gHgL-gp42 complex. Two antibody cocktails synergistically neutralize infection in B cells (5E3+6H2+10E4) and epithelial cells (6H2+10E4) in vitro. Moreover, 5E3 alone and the 5E3+6H2+10E4 cocktail confer potent in vivo protection against lethal EBV challenge in humanized mice. The cryo-EM structure of a heptatomic gHgL-gp42 immune complex reveals non-overlapping epitopes of 5E3, 6H2, and 10E4 on the gHgL-gp42 complex. Structural and functional analyses highlight different neutralization mechanisms for each of the three nAbs. In summary, our results provide insight for the rational design of therapeutics or vaccines against EBV infection.

Epstein-Barr virus infection: the micro and macro worlds

Epstein‒Barr virus (EBV) is a DNA virus that belongs to the human B lymphotropic herpesvirus family and is highly prevalent in the human population. Once infected, a host can experience latent infection because EBV evades the immune system, leading to hosts harboring the virus for their lifetime. EBV is associated with many diseases and causes significant challenges to human health. This review first offers a description of the natural history of EBV infection, clarifies the interaction between EBV and the immune system, and finally focuses on several major types of diseases caused by EBV infection.

Recent Updates on Viral Oncogenesis: Available Preventive and Therapeutic Entities

Human viral oncogenesis is a complex phenomenon and a major contributor to the global cancer burden. Several recent findings revealed cellular and molecular pathways that promote the development and initiation of malignancy when viruses cause an infection. Even, antiviral treatment has become an approach to eliminate the viral infections and prevent the activation of oncogenesis. Therefore, for a better understanding, the molecular pathogenesis of various oncogenic viruses like, hepatitis virus, human immunodeficiency viral (HIV), human papillomavirus (HPV), herpes simplex virus (HSV), and Epstein-Barr virus (EBV), could be explored, especially, to expand many potent antivirals that may escalate the apoptosis of infected malignant cells while sparing normal and healthy ones. Moreover, contemporary therapies, such as engineered antibodies antiviral agents targeting signaling pathways and cell biomarkers, could inhibit viral oncogenesis. This review elaborates the recent advancements in both natural and synthetic antivirals to control viral oncogenesis. The study also highlights the challenges and future perspectives of using antivirals in viral oncogenesis.

Treatment Options for Epstein-Barr Virus-Related Disorders of the Central Nervous System

Epstein-Barr virus (EBV), a causative agent for several types of lymphomas and mucosal cancers, is a human lymphotropic herpesvirus with the capacity to establish lifelong latent infection. More than 90% of the human population worldwide is infected. The primary infection is usually asymptomatic in childhood, whereas infectious mononucleosis (IM) is common when the infection occurs in adolescence. Primary EBV infection, with or without IM, or reactivation of latent infection in immunocompromised individuals have been associated with a wide range of neurologic conditions, such as encephalitis, meningitis, acute disseminated encephalomyelitis, and cerebellitis. EBV is also involved in malignant lymphomas in the brain. An increasing number of reports on EBV-related disorders of the central nervous system (CNS) including the convincing association with multiple sclerosis (MS) have put in focus EBV-related conditions beyond its established link to malignancies. In this review, we present the clinical manifestations of EBV-related CNS-disorders, put them in the context of known EBV biology and focus on available treatment options and future therapeutic approaches.

Immunity and Immune Evasion Mechanisms of Epstein-Barr Virus

Epstein-Barr virus (EBV) is the first human oncogenic virus to be identified, which evades the body's immune surveillance through multiple mechanisms that allow long-term latent infection. Under certain pathological conditions, EBVs undergo a transition from the latent phase to the lytic phase and cause targeted dysregulation of the host immune system, leading to the development of EBV-related diseases. Therefore, an in-depth understanding of the mechanism of developing an immune response to EBV and the evasion of immune recognition by EBV is important for the understanding of the pathogenesis of EBV, which is of great significance for finding strategies to prevent EBV infection, and developing a therapy to treat EBV-associated diseases. In this review, we will discuss the molecular mechanisms of host immunological responses to EBV infection and the mechanisms of EBV-mediated immune evasion during chronic active infection.

A four-part guide to lung immunology: Invasion, inflammation, immunity, and intervention

Lungs are important respiratory organs primarily involved in gas exchange. Lungs interact directly with the environment and their primary function is affected by several inflammatory responses caused by allergens, inflammatory mediators, and pathogens, eventually leading to disease. The immune architecture of the lung consists of an extensive network of innate immune cells, which induce adaptive immune responses based on the nature of the pathogen(s). The balance of immune responses is critical for maintaining immune homeostasis in the lung. Infection by pathogens and physical or genetic dysregulation of immune homeostasis result in inflammatory diseases. These responses culminate in the production of a plethora of cytokines such as TSLP, IL-9, IL-25, and IL-33, which have been implicated in the pathogenesis of several inflammatory and autoimmune diseases. Shifting the balance of Th1, Th2, Th9, and Th17 responses have been the targets of therapeutic interventions in the treatment of these diseases. Here, we have briefly reviewed the innate and adaptive i3mmune responses in the lung. Genetic and environmental factors, and infection are the major causes of dysregulation of various functions of the lung. We have elaborated on the impact of inflammatory and infectious diseases, advances in therapies, and drug delivery devices on this critical organ. Finally, we have provided a comprehensive compilation of different inflammatory and infectious diseases of the lungs and commented on the pros and cons of different inhalation devices for the management of lung diseases. The review is intended to provide a summary of the immunology of the lung, with an emphasis on drug and device development.

Malignancy and viral infections in Sub-Saharan Africa: A review

The burden of malignancy related to viral infection is increasing in Sub-Saharan Africa (SSA). In 2018, approximately 2 million new cancer cases worldwide were attributable to infection. Prevention or treatment of these infections could reduce cancer cases by 23% in less developed regions and about 7% in developed regions. Contemporaneous increases in longevity and changes in lifestyle have contributed to the cancer burden in SSA. African hospitals are reporting more cases of cancer related to infection (e.g., cervical cancer in women and stomach and liver cancer in men). SSA populations also have elevated underlying prevalence of viral infections compared to other regions. Of 10 infectious agents identified as carcinogenic by the International Agency for Research on Cancer, six are viruses: hepatitis B and C viruses (HBV and HCV, respectively), Epstein-Barr virus (EBV), high-risk types of human papillomavirus (HPV), Human T-cell lymphotropic virus type 1 (HTLV-1), and Kaposi's sarcoma herpesvirus (KSHV, also known as human herpesvirus type 8, HHV-8). Human immunodeficiency virus type 1 (HIV) also facilitates oncogenesis. EBV is associated with lymphomas and nasopharyngeal carcinoma; HBV and HCV are associated with hepatocellular carcinoma; KSHV causes Kaposi's sarcoma; HTLV-1 causes T-cell leukemia and lymphoma; HPV causes carcinoma of the oropharynx and anogenital squamous cell cancer. HIV-1, for which SSA has the greatest global burden, has been linked to increasing risk of malignancy through immunologic dysregulation and clonal hematopoiesis. Public health approaches to prevent infection, such as vaccination, safer injection techniques, screening of blood products, antimicrobial treatments and safer sexual practices could reduce the burden of cancer in Africa. In SSA, inequalities in access to cancer screening and treatment are exacerbated by the perception of cancer as taboo. National level cancer registries, new screening strategies for detection of viral infection and public health messaging should be prioritized in SSA's battle against malignancy. In this review, we discuss the impact of carcinogenic viruses in SSA with a focus on regional epidemiology.

The Epstein-Barr Virus Glycoprotein BDLF2 Is Essential for Efficient Viral Spread in Stratified Epithelium

Epstein-Barr virus (EBV) is a ubiquitous human pathogen that infects the majority of the adult population regardless of socioeconomic status or geographical location. EBV primarily infects B and epithelial cells and is associated with different cancers of these cell types, such as Burkitt lymphoma and nasopharyngeal carcinoma. While the life cycle of EBV in B cells is well understood, EBV infection within epithelium is not, largely due to the inability to model productive replication in epithelium in vitro. Organotypic cultures generated from primary human keratinocytes can model many aspects of EBV infection, including productive replication in the suprabasal layers. The EBV glycoprotein BDLF2 is a positional homologue of the murine gammaherpesvirus-68 protein gp48, which plays a role in intercellular spread of viral infection, though sequence homology is limited. To determine the role that BDLF2 plays in EBV infection, we generated a recombinant EBV in which the BDLF2 gene has been replaced with a puromycin resistance gene. The ΔBDLF2 recombinant virus infected both B cell and HEK293 cell lines and was able to immortalize primary B cells. However, the loss of BDLF2 resulted in substantially fewer infected cells in organotypic cultures compared to wild-type virus. While numerous clusters of infected cells representing a focus of infection are observed in wild-type-infected organotypic cultures, the majority of cells observed in the absence of BDLF2 were isolated cells, suggesting that the EBV glycoprotein BDLF2 plays a major role in intercellular viral spread in stratified epithelium. IMPORTANCE The ubiquitous herpesvirus Epstein-Barr virus (EBV) is associated with cancers of B lymphocytes and epithelial cells and is primarily transmitted in saliva. While several models exist for analyzing the life cycle of EBV in B lymphocytes, models of EBV infection in the epithelium have more recently been established. Using an organotypic culture model of epithelium that we previously determined accurately reflects EBV infection in situ, we have ascertained that the loss of the viral envelope protein BDLF2 had little effect on the EBV life cycle in B cells but severely restricted the number of infected cells in organotypic cultures. Loss of BDLF2 has a substantial impact on the size of infected areas, suggesting that BDLF2 plays a specific role in the spread of infection in stratified epithelium.

Comprehensive analysis of aberrantly expressed circRNAs, mRNAs and lncRNAs in patients with nasopharyngeal carcinoma

BACKGROUND

The location of nasopharyngeal cancer is hidden, so it is difficult to diagnose at an early stage. In this study, we aimed to investigate the expression profiles of circRNAs, mRNAs and IncRNAs and to provide some basis for further studies.

METHODS

Expression profiles of circRNAs, mRNAs, and lncRNAs were analyzed using microarray techniques. The differentially expressed ncRNA was calculated by bioinformatics.

RESULTS

A total of 3048 circRNAs, 2179 lncRNAs, and 2015 mRNAs were detected to be significantly differentially expressed in NPC. The most upregulated circRNAs, lncRNAs, and mRNAs were hsa-circ-0067562, NONHSAT232922.1, and HOXB13, respectively. And, the most downregulated circRNAs, lncRNAs, and mRNAs were hsa_circ_0078837, lnc-TTC8-4:3, and LTF, respectively. The number of upregulated DE lncRNAs was more than twice than those downregulated. Our data showed that 80.44% of pairs of lncRNAs and cis-mRNAs demonstrated positive correlations. For lncRNAs and trans-mRNAs pairs, 53.7% of pairs showed positive correlation. LncRNA-mediated cis regulation is a prevalent regulatory mode in the development of nasopharyngeal carcinoma. CR1, LRMP and SORBS2 are predicted to be mediated not only by cis-acting lncRNA modes of action, but also by trans-acting lncRNA mechanisms. Additionally, we constructed a diagnostic prediction model with a high sensitivity and specificity.

CONCLUSION

Our study characterized the landscape of circRNAs, mRNAs and lncRNAs in NPC tissue and provided novel insights into the molecular mechanisms of NPC.

Urgency and necessity of Epstein-Barr virus prophylactic vaccines

Epstein-Barr virus (EBV), a γ-herpesvirus, is the first identified oncogenic virus, which establishes permanent infection in humans. EBV causes infectious mononucleosis and is also tightly linked to many malignant diseases. Various vaccine formulations underwent testing in different animals or in humans. However, none of them was able to prevent EBV infection and no vaccine has been approved to date. Current efforts focus on antigen selection, combination, and design to improve the efficacy of vaccines. EBV glycoproteins such as gH/gL, gp42, and gB show excellent immunogenicity in preclinical studies compared to the previously favored gp350 antigen. Combinations of multiple EBV proteins in various vaccine designs become more attractive approaches considering the complex life cycle and complicated infection mechanisms of EBV. Besides, rationally designed vaccines such as virus-like particles (VLPs) and protein scaffold-based vaccines elicited more potent immune responses than soluble antigens. In addition, humanized mice, rabbits, as well as nonhuman primates that can be infected by EBV significantly aid vaccine development. Innovative vaccine design approaches, including polymer-based nanoparticles, the development of effective adjuvants, and antibody-guided vaccine design, will further enhance the immunogenicity of vaccine candidates. In this review, we will summarize (i) the disease burden caused by EBV and the necessity of developing an EBV vaccine; (ii) previous EBV vaccine studies and available animal models; (iii) future trends of EBV vaccines, including activation of cellular immune responses, novel immunogen design, heterologous prime-boost approach, induction of mucosal immunity, application of nanoparticle delivery system, and modern adjuvant development.

A high-throughput neutralizing assay for antibodies and sera evaluation against Epstein-Barr virus

BACKGROUND

Epstein-Barr virus (EBV) is a wide-spread human herpesvirus that is highly associated with infectious mononucleosis and several malignancies. Evaluation of EBV neutralizing antibody titers is important for serological studies, vaccine development and monoclonal antibody screening. The traditional method based on antibody inhibition of EBV transformation of B cells is very time-consuming. A more practical flow cytometry-based (FCM) approach to evaluate neutralizing titers is not amenable to achieving high-throughput evaluation of large-scale samples. A high-throughput approach is urgently needed.

RESULTS

Here, we present a rapid and high-throughput method based on high content imaging system (HCIS) analysis. EBV titers determined by the HCIS-based assay were similar to those obtained by the FCM-based assay. Neutralizing titers of sera and monoclonal antibodies measured by the HCIS-based assay strongly correlated with titers measured by the FCM-based assay. HCIS assays showed a strong correlation between B cell infection neutralizing titers and the anti-gp350 IgG titers in healthy EBV carriers and monkey sera. Finally, anti-gHgL IgG titers from sera of healthy EBV carriers significantly correlated with epithelial cell infection neutralizing titers.

CONCLUSIONS

This HCIS-based assay is a high-throughput assay to determine viral titers and evaluate neutralizing potentials of sera and monoclonal antibodies. This HCIS-based assay will aid the development of vaccines and therapeutic monoclonal antibody against EBV.

How EBV Infects: The Tropism and Underlying Molecular Mechanism for Viral Infection

The Epstein-Barr virus (EBV) is associated with a variety of human malignancies, including Burkitt's lymphoma, Hodgkin's disease, nasopharyngeal carcinoma and gastric cancers. EBV infection is crucial for the oncogenesis of its host cells. The prerequisite for the establishment of infection is the virus entry. Interactions of viral membrane glycoproteins and host membrane receptors play important roles in the process of virus entry into host cells. Current studies have shown that the main tropism for EBV are B cells and epithelial cells and that EBV is also found in the tumor cells derived from NK/T cells and leiomyosarcoma. However, the process of EBV infecting B cells and epithelial cells significantly differs, relying on heterogenous glycoprotein-receptor interactions. This review focuses on the tropism and molecular mechanism of EBV infection. We systematically summarize the key molecular events that mediate EBV cell tropism and its entry into target cells and provide a comprehensive overview.

Epstein-Barr virus: Biology and clinical disease

Epstein-Barr virus (EBV) is a ubiquitous, oncogenic virus that is associated with a number of different human malignancies as well as autoimmune disorders. The expression of EBV viral proteins and non-coding RNAs contribute to EBV-mediated disease pathologies. The virus establishes life-long latency in the human host and is adept at evading host innate and adaptive immune responses. In this review, we discuss the life cycle of EBV, the various functions of EBV-encoded proteins and RNAs, the ability of the virus to activate and evade immune responses, as well as the neoplastic and autoimmune diseases that are associated with EBV infection in the human population.

Evolution of functional antibodies following acute Epstein-Barr virus infection

While Epstein-Barr virus causes mostly asymptomatic infection, associated malignancies, and autoimmune and lymphoproliferative diseases occur. To dissect the evolution of humoral immune responses over the course of EBV infection and to gain a better understanding of the potential contribution of antibody (Ab) function to viral control, we comprehensively profiled Ab specificities and Fc-functionalities using systems serology and VirScan. Ab functions against latent (EBNA1), early (p47/54) and two late (gp350/220 and VCA-p18) EBV proteins were overall modest and/or short-lived, differing from humoral responses induced during acute infection by other viruses such as HIV. In the first year post infection, only p18 elicited robust IgM-driven complement deposition and IgG-driven neutrophil phagocytosis while responses against EBNA-1 were largely Fc-functionally silent and only matured during chronic infection to drive phagocytosis. In contrast, Abs against Influenza virus readily mediated broad Fc-activity in all participants. These data suggest that EBV evades the induction of robust Fc-functional Abs, potentially due to the virus’ life cycle, switching from lytic to latent stages during infection.

While previously thought to be largely innocuous, emerging data clearly highlight the pathological role of lifelong EBV infection in driving autoimmunity and malignancies in a small, but not insignificant portion of the population. We therefore aimed to define potential humoral mechanisms associated with viral control, beyond neutralizing Abs, by systematically focusing on antibody Fc-functional activities during acute to convalescent EBV infection applying technologies such as systems serology and VirScan. We found that functions against EBV proteins were overall only modest and either short-lived or delayed, differing from functional antibody responses induced during acute infection by other viruses such as HIV. These data suggest that EBV evades the induction of robust Fc-functional Abs thereby potentially facilitating lifelong, persistent infection with all its consequences.

A brief overview of the Epstein Barr virus and its association with Burkitt's lymphoma

Epstein Barr virus (EBV) is known as an oncovirus and associates with several human malignancies such as Burkitt's lymphoma, other non-Hodgkin lymphomas, nasopharyngeal carcinoma, Hodgkin's disease, gastric adenocarcinoma, etc. in Burkitt's lymphoma, and the key event is the translocation of MYC gene, that increase of cell survival and aberrant expression of MYC gene. The biology of EBV and its function in the development of Burkitt's lymphoma are discussed in this review

Immunization with a self-assembling nanoparticle vaccine displaying EBV gH/gL protects humanized mice against lethal viral challenge

Epstein-Barr virus (EBV) is a cancer-associated pathogen responsible for 165,000 deaths annually. EBV is also the etiological agent of infectious mononucleosis and is linked to multiple sclerosis and rheumatoid arthritis. Thus, an EBV vaccine would have a significant global health impact. EBV is orally transmitted and has tropism for epithelial and B cells. Therefore, a vaccine would need to prevent infection of both in the oral cavity. Passive transfer of monoclonal antibodies against the gH/gL glycoprotein complex prevent experimental EBV infection in humanized mice and rhesus macaques, suggesting that gH/gL is an attractive vaccine candidate. Here, we evaluate the immunogenicity of several gH/gL nanoparticle vaccines. All display superior immunogenicity relative to monomeric gH/gL. A nanoparticle displaying 60 copies of gH/gL elicits antibodies that protect against lethal EBV challenge in humanized mice, whereas antibodies elicited by monomeric gH/gL do not. These data motivate further development of gH/gL nanoparticle vaccines for EBV.

Four Decades of Prophylactic EBV Vaccine Research: A Systematic Review and Historical Perspective

Background

Epstein-Barr virus (EBV) is the causal agent of infectious mononucleosis and has been associated with various cancers and autoimmune diseases. Despite decades of research efforts to combat this major global health burden, there is no approved prophylactic vaccine against EBV. To facilitate the rational design and assessment of an effective vaccine, we systematically reviewed pre-clinical and clinical prophylactic EBV vaccine studies to determine the antigens, delivery platforms, and animal models used in these studies.

Methods

We searched Cochrane Library, ClinicalTrials.gov, Embase, PubMed, Scopus, Web of Science, WHO’s Global Index Medicus, and Google Scholar from inception to June 20, 2020, for EBV prophylactic vaccine studies focused on humoral immunity.

Results

The search yielded 5,614 unique studies. 36 pre-clinical and 4 clinical studies were included in the analysis after screening against the exclusion criteria. In pre-clinical studies, gp350 was the most commonly used immunogen (33 studies), vaccines were most commonly delivered as monomeric proteins (12 studies), and mice were the most used animal model to test immunogenicity (15 studies). According to an adaptation of the CAMARADES checklist, 4 pre-clinical studies were rated as very high, 5 as high, 13 as moderate quality, 11 as poor, and 3 as very poor. In clinical studies, gp350 was the sole vaccine antigen, delivered in a vaccinia platform (1 study) or as a monomeric protein (3 studies). The present study was registered in PROSPERO (CRD42020198440).

Conclusions

Four major obstacles have prevented the development of an effective prophylactic EBV vaccine: undefined correlates of immune protection, lack of knowledge regarding the ideal EBV antigen(s) for vaccination, lack of an appropriate animal model to test vaccine efficacy, and lack of knowledge regarding the ideal vaccine delivery platform. Our analysis supports a multivalent antigenic approach including two or more of the five main glycoproteins involved in viral entry (gp350, gB, gH/gL, gp42) and a multimeric approach to present these antigens. We anticipate that the application of two underused challenge models, rhesus macaques susceptible to rhesus lymphocryptovirus (an EBV homolog) and common marmosets, will permit the establishment of in vivo correlates of immune protection and attainment of more generalizable data.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=198440, identifier PROSPERO I.D. CRD4202019844.

A Rare Case of Epstein-Barr Virus-Positive T-Cell Lymphoma in the Skin of an Immunocompromised Patient

ABSTRACT

Immunodeficiency-associated lymphoproliferative disorders are associated with latent infection by Epstein-Barr virus (EBV). Most cases of EBV-positive immunodeficiency-associated lymphoproliferative disorders arise from B cells, although some are of T-cell or natural killer origin. Cutaneous involvement is unusual and sporadically reported in the literature. We describe a rare case of an EBV-positive T-cell lymphoma presenting in the skin of a 32-year-old woman using adalimumab for neurosarcoidosis.

Production of PfEMP1-Specific Human Monoclonal Antibodies from Naturally Immune Individuals

Plasmodium falciparum parasites express variable surface antigens on the infected erythrocyte surface allowing adhesion to human host receptors on the blood and endothelial cells, which can result in immune evasion. One of the most studied and key antigens in adhesion is the highly polymorphic PfEMP1. However, despite the vast variation in the PfEMP1 antigens, they are the main targets of naturally acquired immunity and are therefore promising candidates for malaria vaccine development. Generating PfEMP1-specific human monoclonal antibodies from naturally immune individuals will help to determine the best targets of protection from clinical disease. Immortalization of human B cells is one of the oldest and most efficient techniques to generate human monoclonal antibodies. Nevertheless, most protocols require flow cytometry-based cell sorting, which can be a limiting factor for many laboratories. This chapter describes an efficient protocol for the generation of PfEMP1-specific human monoclonal antibodies from malaria immune individuals that can be performed without the use of advanced cell-sorting techniques.

Prophylactic and Therapeutic EBV Vaccines: Major Scientific Obstacles, Historical Progress, and Future Direction

The Epstein-Barr virus (EBV) infects more than 95% of adults worldwide and is associated with various malignant tumors and immune diseases, imparting a huge disease burden on the human population. Available EBV vaccines are imminent. Prophylactic vaccines can effectively prevent the spread of infection, whereas therapeutic vaccines mainly stimulate cell-mediated immunity and kill infected cells, thus curbing the development of malignant tumors. Nevertheless, there are still no approved EBV vaccines after decades of effort. The complexity of the EBV life cycle, the lack of appropriate animal models, and the limited reports on adjuvant selection and immune responses are gravely impeding progress in EBV vaccines. The soluble gp350 vaccine could reduce the incidence of infectious mononucleosis (IM), which seemed to offer hope, but could not prevent EBV infection. Continuous research and vaccine trials provide deep insights into the structural biology of viruses, the designs for immunogenicity, and the evolving vaccine platforms. Moreover, the new vaccine candidates are expected to achieve further success via combined immunization to elicit both a dual protection of B cells and epithelial cells, and sustainable immunization against infected cells at several phases of infection.

Epstein-Barr virus (EBV) hyperimmune globulin isolated from donors with high gp350 antibody titers protect humanized mice from challenge with EBV

Primary infection with Epstein-Barr virus (EBV) is associated with post-transplant lymphoproliferative disease and severe disease in patients with X-linked lymphoproliferative disease; no therapies are approved to prevent EBV infection in these patients. Hyperimmune globulin has been used to prevent some virus infections in immunocompromised persons. Here, we identified plasma donors with high titers of EBV gp350 and EBV B cell neutralizing antibodies. Pooled IgG isolated from these donors was compared to intravenous immunoglobulin (IVIG) for its ability to reduce viral load in the blood in humanized mice challenged with EBV. Mice that received EBV hyperimmune globulin had significantly reduced EBV DNA copy numbers compared to animals that received saline control; however, while animals that received EBV hyperimmune globulin had lower EBV DNA copies than those that received IVIG, the difference was not significant. Thus, while EBV hyperimmune globulin reduced viral load compared to IVIG, the effect was modest.

NK cells eliminate Epstein-Barr virus bound to B cells through a specific antibody-mediated uptake

Epstein Barr virus (EBV) causes a highly prevalent and lifelong infection contributing to the development of some malignancies. In addition to the key role played by T cells in controlling this pathogen, NK cells mediate cytotoxicity and IFNγ production in response to EBV-infected B cells in lytic cycle, both directly and through antibody (Ab)-dependent activation. We recently described that EBV-specific Ab-dependent NK cell interaction with viral particles (VP) bound to B cells triggered degranulation and TNFα secretion but not B cell lysis nor IFNγ production. In this report we show that NK cell activation under these conditions reduced B cell transformation by EBV. NK cells eliminated VP from the surface of B cells through a specific and active process which required tyrosine kinase activation, actin polymerization and Ca2+, being independent of proteolysis and perforin. VP were displayed at the NK cell surface before being internalized and partially shuttled to early endosomes and lysosomes. VP transfer was encompassed by a trogocytosis process including the EBV receptor CD21, together with CD19 and CD20. Our study reveals a novel facet of the antibody-dependent NK cell mediated response to this viral infection.

Epstein-Barr virus (EBV) is a member of the herpesvirus family which causes a frequent and lifelong infection. The immune system is unable to fully eliminate the virus, which remains dormant in infected B lymphocytes. EBV reactivation leads to the production of new infective particles, spreading to other cells and favoring its transmission. EBV infection goes generally unnoticed in healthy individuals, though it may occasionally cause a disease termed Infectious Mononucleosis, as well as severe disorders in patients with a defective immune response. Remarkably, EBV has oncogenic potential contributing to the development of some tumors, and has been associated to autoimmune diseases. T lymphocytes and Natural Killer (NK) cells play an essential role in the defense against EBV, killing infected cells when the virus reactivates. Antiviral NK cell functions may be also triggered by antibodies (Ab) recognizing infected cells. In this report we provide the first evidence supporting that NK cells in combination with anti-EBV Ab are able to eliminate the virus attached to the surface of B cells, reducing their infection without killing them.

Conserved and Distinct Elements of Phagocytosis in Human and C. elegans

Endocytosis provides the cellular nutrition and homeostasis of organisms, but pathogens often take advantage of this entry point to infect host cells. This is counteracted by phagocytosis that plays a key role in the protection against invading microbes both during the initial engulfment of pathogens and in the clearance of infected cells. Phagocytic cells balance two vital functions: preventing the accumulation of cell corpses to avoid pathological inflammation and autoimmunity, whilst maintaining host defence. In this review, we compare elements of phagocytosis in mammals and the nematode Caenorhabditis elegans. Initial recognition of infection requires different mechanisms. In mammals, pattern recognition receptors bind pathogens directly, whereas activation of the innate immune response in the nematode rather relies on the detection of cellular damage. In contrast, molecules involved in efferocytosis—the engulfment and elimination of dying cells and cell debris—are highly conserved between the two species. Therefore, C. elegans is a powerful model to research mechanisms of the phagocytic machinery. Finally, we show that both mammalian and worm studies help to understand how the two phagocytic functions are interconnected: emerging data suggest the activation of innate immunity as a consequence of defective apoptotic cell clearance.

New aspects in the regulation of human B cell functions by complement receptors CR1, CR2, CR3 and CR4

The involvement of complement in the regulation of antibody responses has been known for long. By now several additional B cell functions - including cytokine production and antigen presentation - have also been shown to be regulated by complement proteins. Most of these important activities are mediated by receptors interacting with activation fragments of the central component of the complement system C3, such as C3b, iC3b and C3d, which are covalently attached to antigens and immune complexes. This review summarizes the role of complement receptors interacting with these ligands, namely CR1 (CD35), CR2 (CD21), CR3 (CD11b/CD18) and CR4 (CD11c/CD18) expressed by B cells in health and disease. Although we focus on human B lymphocytes, we also aim to call the attention to important differences between human and mouse systems.

Altered levels of complement components associated with non-immediate drug hypersensitivity reactions

Nonimmediate drug hypersensitivity reactions (niDHRs) range from mild-type maculopapular exanthema (MPE) to severe type Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) with unentirely clarified pathogenesis. This study sought to explore whether complement components participated in niDHRs. The participants comprised of three groups as follows: MPE (n = 65), SJS/TEN (n = 13, contains 7 SJS, 2 SJS-TEN overlap and 4 TEN), and equal healthy controls (n = 78). Skin pathological changes were confirmed by hematoxylin and eosin staining. The mRNA and protein levels of complement components were assessed. In the MPE group, there were no alterations in complement components at the protein and mRNA levels found except for a decrease in factor H mRNA. In the SJS/TEN group, up-regulated levels of C3aR and C5aR mRNA and down-regulated factor H mRNA levels in blood were noted. A lower plasma protein level of C3, Factor H and a higher level of C3a, C5, C5a, C5b-9, Factor B (p < 0.05) were found in the SJS/TEN group compared with in the control (p < 0.05). In SJS/TEN skin lesions, indirect immunofluorescence assays showed positive specific staining for C5b-9, but not C3. Both C3aR and C5aR were positive staining in the SJS/TEN samples, while staining for C1q, mannose-binding lectin (MBL), Factor B, and Factor H were only weak or negative. The findings reported here are the first to define the expression profiles/extent of the presence of various complement components at the mRNA and protein levels in niDHRs, especially in SJS/TEN. These altered complement components might, at least in part, be integral to the mechanisms underlying the pathogeneses of SJS and TEN.

The Status and Prospects of Epstein-Barr Virus Prophylactic Vaccine Development

Epstein–Barr virus (EBV) is a human herpesvirus that is common among the global population, causing an enormous disease burden. EBV can directly cause infectious mononucleosis and is also associated with various malignancies and autoimmune diseases. In order to prevent primary infection and subsequent chronic disease, efforts have been made to develop a prophylactic vaccine against EBV in recent years, but there is still no vaccine in clinical use. The outbreak of the COVID-19 pandemic and the global cooperation in vaccine development against SARS-CoV-2 provide insights for next-generation antiviral vaccine design and opportunities for developing an effective prophylactic EBV vaccine. With improvements in antigen selection, vaccine platforms, formulation and evaluation systems, novel vaccines against EBV are expected to elicit dual protection against infection of both B lymphocytes and epithelial cells. This would provide sustainable immunity against EBV-associated malignancies, finally enabling the control of worldwide EBV infection and management of EBV-associated diseases.

Meet the Insidious Players: Review of Viral Infections in Head and Neck Cancer Etiology with an Update on Clinical Trials

Head and neck cancers (HNC) occur in the upper aerodigestive tract and are among the most common cancers. The etiology of HNC is complex, involving many factors, including excessive tobacco and alcohol consumption; over the last two decades, oncogenic viruses have also been recognized as an important cause of HNC. Major etiological agents of nasopharynx carcinoma and oropharyngeal carcinoma include Epstein-Barr virus (EBV) and human papillomaviruses (HPVs), both of which are able to interfere with cell cycle control. Additionally, the association of hepatitis C and hepatitis B infection was observed in oral cavity, oropharyngeal, laryngeal, and nasopharyngeal cancers. Overall prognoses depend on anatomic site, stage, and viral status. Current treatment options, including radiotherapy, chemotherapy, targeted therapies and immunotherapies, are distributed in order to improve overall patient prognosis and survival rates. However, the interplay between viral genome sequences and the health, disease, geography, and ethnicity of the host are crucial for understanding the role of viruses and for development of potential personalized treatment and prevention strategies. This review provides the most comprehensive analysis to date of a vast field, including HNC risk factors, as well as viral mechanisms of infection and their role in HNC development. Additionally, currently available treatment options investigated through clinical practice are emphasized in the paper.

The Human Cytomegalovirus UL116 Glycoprotein Is a Chaperone to Control gH-Based Complexes Levels on Virions

Human cytomegalovirus (HCMV) relies in large part upon the viral membrane fusion glycoprotein B and two alternative gH/gL complexes, gH/gL/gO (Trimer) and gH/gL/UL128/UL130/UL131A (Pentamer) to enter into cells. The relative amounts of Trimer and Pentamer vary among HCMV strains and contribute to differences in cell tropism. Although the viral ER resident protein UL148 has been shown to interact with gH to facilitate gO incorporation, the mechanisms that favor the assembly and maturation of one complex over another remain poorly understood. HCMV virions also contain an alternative non-disulfide bound heterodimer comprised of gH and UL116 whose function remains unknown. Here, we show that disruption of HCMV gene UL116 causes infectivity defects of ∼10-fold relative to wild-type virus and leads to reduced expression of both gH/gL complexes in virions. Furthermore, gH that is not covalently bound to other viral glycoproteins, which are readily detected in wild-type HCMV virions, become undetectable in the absence of UL116 suggesting that the gH/UL116 complex is abundant in virions. We find evidence that UL116 and UL148 interact during infection indicating that the two proteins might cooperate to regulate the abundance of HCMV gH complexes. Altogether, these results are consistent with a role of UL116 as a chaperone for gH during the assembly and maturation of gH complexes in infected cells.

Immunization with a Self-Assembled Nanoparticle Vaccine Elicits Potent Neutralizing Antibody Responses against EBV Infection

Epstein-Barr virus (EBV) infection is a global health concern infecting over 90% of the population. However, there is no currently available vaccine. EBV primarily infects B cells, where the major glycoprotein 350 (gp350) is the main target of neutralizing antibodies. Given the advancement of nanoparticle vaccines, we describe rationally designed vaccine modalities presenting 60 copies of gp350 on self-assembled nanoparticles in a repetitive array. In a mouse model, gp350s on lumazine synthase (LS) and I3-01 adjuvanted with MF59 or aluminum hydroxide (Alhydrogel) elicited over 65- to 133-fold higher neutralizing antibody titers than the corresponding gp350 monomer to EBV. Furthermore, immunization with gp350D₁₂₃-LS and gp350D₁₂₃-I3-01 vaccine induced a Th2-biased response. For the nonhuman primate model, gp350D₁₂₃-LS in MF59 elicited higher titers of total IgG and neutralizing antibodies than the monomeric gp350D₁₂₃. Overall, these results support gp350D₁₂₃-based nanoparticle vaccine design as a promising vaccine candidate for potent protection against EBV infection.

Tripartite Motif 22 (TRIM22) protein restricts herpes simplex virus 1 by epigenetic silencing of viral immediate-early genes

Intrinsic resistance is a crucial line of defense against virus infections, and members of the Tripartite Ring Interaction Motif (TRIM) family of proteins are major players in this system, such as cytoplasmic TRIM5α or nuclear promyelocytic leukemia (PML/TRIM19) protein. Previous reports on the antiviral function of another TRIM protein, TRIM22, emphasized its innate immune role as a Type I and Type II interferon-stimulated gene against RNA viruses. This study shows that TRIM22 has an additional intrinsic role against DNA viruses. Here, we report that TRIM22 is a novel restriction factor of HSV-1 and limits ICP0-null virus replication by increasing histone occupancy and heterochromatin, thereby reducing immediate-early viral gene expression. The corresponding wild-type equivalent of the virus evades the TRIM22-specific restriction by a mechanism independent of ICP0-mediated degradation. We also demonstrate that TRIM22 inhibits other DNA viruses, including representative members of the β- and γ- herpesviruses. Allelic variants in TRIM22 showed different degrees of anti-herpesviral activity; thus, TRIM22 genetic variability may contribute to the varying susceptibility to HSV-1 infection in humans. Collectively, these results argue that TRIM22 is a novel restriction factor and expand the list of restriction factors functioning in the infected cell nucleus to counter DNA virus infection.

The host immune response to herpesviruses includes intrinsic immunity, which is a constitutively active line of defense. Members of the Tripartite Motif (TRIM) superfamily of proteins, such as cytoplasmic TRIM5α and nuclear TRIM19, are examples of such restriction factors against the prototypical α-herpesvirus, herpes simplex virus-1 (HSV-1). Previous reports on the antiviral function of the protein encoded by TRIM22, a gene closely related to the TRIM5 gene, emphasized its antiretroviral role. We show that TRIM22 has an additional role as a restriction factor against herpesviruses. We found that TRIM22 inhibits a mutant form of HSV-1, by promoting chromatin compaction of the viral DNA encoding immediate-early viral genes–this consequently inhibits viral replication and reduces virus yields. Unlike other restriction factors that are degraded by the viral infected cell polypeptide 0 (ICP0), TRIM22 is not degraded by ICP0. We also show that TRIM22 inhibits representative members of the β-herpesvirus (cytomegalovirus) and γ- herpesviruses (Epstein-Barr virus). In addition, different TRIM22 genetic variants show differing levels of HSV-1 inhibition. Together, these results argue for the importance of the TRIM22 gene as a restriction factor against herpesviruses, and offer a novel avenue for further investigation on the role of TRIM genes in host genetic variation in herpesviral susceptibility.

Mast cells and complement system: Ancient interactions between components of innate immunity

The emergence and evolution of the complement system and mast cells (MCs) can be traced back to sea urchins and the ascidian Styela plicata, respectively. Acting as a cascade of enzymatic reactions, complement is activated through the classical (CP), the alternative (AP), and the lectin pathway (LP) based on the recognized molecules. The system's main biological functions include lysis, opsonization, and recruitment of phagocytes. MCs, beyond their classic role as master cells of allergic reactions, play a role in other settings, as well. Thus, MCs are considered as extrahepatic producers of complement proteins. They express various complement receptors, including those for C3a and C5a. C3a and C5a not only activate the C3aR and C5aR expressing MCs but also act as chemoattractants for MCs derived from different anatomic sites, such as from the bone marrow, human umbilical cord blood, or skin in vitro. Cross talk between MCs and complement is facilitated by the production of complement proteins by MCs and their activation by the MC tryptase. The coordinated activity between MCs and the complement system plays a key role, for example, in a number of allergic, cutaneous, and vascular diseases. At a molecular level, MCs and complement system interactions are based on the production of several complement zymogens by MCs and their activation by MC-released proteases. Additionally, at a cellular level, MCs act as potent effector cells of complement activation by expressing receptors for C3a and C5a through which their chemoattraction and activation are mediated by anaphylatoxins in a paracrine and autocrine fashion.

Vaccination against the Epstein-Barr virus

Epstein-Barr virus (EBV) was the first human tumor virus being discovered and remains to date the only human pathogen that can transform cells in vitro. 55 years of EBV research have now brought us to the brink of an EBV vaccine. For this purpose, recombinant viral vectors and their heterologous prime-boost vaccinations, EBV-derived virus-like particles and viral envelope glycoprotein formulations are explored and are discussed in this review. Even so, cell-mediated immune control by cytotoxic lymphocytes protects healthy virus carriers from EBV-associated malignancies, antibodies might be able to prevent symptomatic primary infection, the most likely EBV-associated pathology against which EBV vaccines will be initially tested. Thus, the variety of EBV vaccines reflects the sophisticated life cycle of this human tumor virus and only vaccination in humans will finally be able to reveal the efficacy of these candidates. Nevertheless, the recently renewed efforts to develop an EBV vaccine and the long history of safe adoptive T cell transfer to treat EBV-associated malignancies suggest that this oncogenic γ-herpesvirus can be targeted by immunotherapies. Such vaccination should ideally implement the very same immune control that protects healthy EBV carriers.

Inhibitory effect of simiao qingwen baidu decoction on epstein-barr virus EA, VCA expression and DNA replication in vitro

This article aims to investigate the role of Simiao Qingwen Baidu Decoction (traditional Chinese medicine) in Epstein-Barr virus (EBV)-induced infectious mononucleosis. Sprague Dawley rats were given Simiao Qingwen Baidu Decoction by gavage, and the medicated serum was collected. EBV-latent infected human Burkitt lymphomas Raji and EBV-transformed marmosets B lymphoblast cell B95-8 were treated with medicated serum. CCK8 assay and flow cytometry were performed to detect cell proliferation and apoptosis. Indirect immunofluorescence assay was performed to analyze EA or VCA positive expression. The copy-number of EBV-DNA and the gene expression were detected by quantitative PCR or quantitative real-time PCR. We found that the medicated serum inhibited proliferation of Raji and B95-8 cells, especially 10 %-medicated serum. The 10 %-medicated serum significantly suppressed EA expression in Raji cells and VCA expression in B95-8 cells. The expression of BZLF1, BRLF1, BMLF1 and EBNA-1 in Raji cells was significantly inhibited by 10 %-medicated serum. 10 %-medicated serum caused a decrease in the copy-number of EBV-DNA in Raji cells. In conclusion, our data imply that Simiao Qingwen Baidu Decoction represses the expression of EA and VCA, and EBV-DNA replication. Thus, our work suggests that Simiao Qingwen Baidu Decoction may play a vital role in anti-EBV.

TLR4 896A/G and TLR9 1174G/A polymorphisms are associated with the risk of infectious mononucleosis

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns and activate innate and adaptive immune responses. Single nucleotide polymorphisms (SNPs) within the TLR genes may influence host–pathogen interactions and can have an impact on the progression of infectious diseases. The present study aimed to investigate the genotype distribution of TLR2 (2029C/T, rs121917864; 2258G/A, rs5743708), TLR4 (896A/G, rs4986790), and TLR9 (− 1237T/C, rs5743836; − 1486T/C, rs187084; 1174G/A, rs352139; and 2848C/T, rs352140) polymorphisms in 149 children and adolescents with infectious mononucleosis (IM) and 140 healthy individuals. The potential association of TLR SNPs with the clinical manifestations of EBV infection was also studied. The presence of TLR2, TLR4, and TLR9 SNPs was identified by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). EBV DNA loads were detected by quantitative real-time PCR assay. The TLR4 896 GG and the TLR9 1174 GA genotypes were associated with an increased risk of EBV-related IM in examined patients (p = 0.014 and p = 0.001, respectively). The heterozygous genotype of the TLR4 896A/G SNP was associated with an increased risk of elevated liver enzyme levels and leukocytosis (p < 0.05). Our preliminary study revealed that the TLR4 896A/G and the TLR9 1174G/A polymorphisms seem to be related to the course of acute EBV infection in children and adolescents.

Epithelial cell infection by Epstein-Barr virus

Epstein-Barr Virus (EBV) is etiologically associated with multiple human malignancies including Burkitt lymphoma and Hodgkin disease as well as nasopharyngeal and gastric carcinoma. Entry of EBV into target cells is essential for virus to cause disease and is mediated by multiple viral envelope glycoproteins and cell surface associated receptors. The target cells of EBV include B cells and epithelial cells. The nature and mechanism of EBV entry into these cell types are different, requiring different glycoprotein complexes to bind to specific receptors on the target cells. Compared to the B cell entry mechanism, the overall mechanism of EBV entry into epithelial cells is less well known. Numerous receptors have been implicated in this process and may also be involved in additional processes of EBV entry, transport, and replication. This review summarizes EBV glycoproteins, host receptors, signal molecules and transport machinery that are being used in the epithelial cell entry process and also provides a broad view for related herpesvirus entry mechanisms.

gp96 Is Critical for both Human Herpesvirus 6A (HHV-6A) and HHV-6B Infections

Human herpesviruses 6A and 6B (HHV-6A and HHV-6B, respectively) are two virus species in the betaherpesvirus subfamily that exhibit T cell tropism. CD46 and CD134 are the cellular receptors for HHV-6A and HHV-6B, respectively. Interestingly, the efficiency of HHV-6A/6B entry is different among different types of target cells despite similar receptor expression levels on these cells. Here, we found that the cellular factor gp96 (also known as glucose-regulated protein 94 [GRP94]) is expressed on the cell surface and interacts with viral glycoprotein Q1 (gQ1) during virus entry. gp96 cell surface expression levels are associated with the efficiency of HHV-6A and HHV-6B entry into target cells. Both loss-of-function and gain-of-function experiments indicated that gp96 plays an important role in HHV-6 infection. Our findings provide new insight into the HHV-6 entry process and might suggest novel therapeutic targets for HHV-6 infection.IMPORTANCE Although new clinical importance has been revealed for human herpesviruses 6A (HHV-6A) and 6B, much is still unknown about the life cycles of these viruses in target cells. We identified a novel cellular factor, gp96, that is critical for both HHV-6A and -6B entry into host cells. As gp96 can function as an adjuvant in vaccine development for both infectious agents and cancers, it can be a potential therapeutic target for infection by these two viruses.

Neutralizing Antibodies Protect against Oral Transmission of Lymphocryptovirus

Epstein-Barr virus (EBV) is a cancer-associated pathogen for which there is no vaccine. Successful anti-viral vaccines elicit antibodies that neutralize infectivity; however, it is unknown whether neutralizing antibodies prevent EBV acquisition. Here we assessed whether passively delivered AMMO1, a monoclonal antibody that neutralizes EBV in a cell-type-independent manner, could protect against experimental EBV challenge in two animal infection models. When present prior to a high-dose intravenous EBV challenge, AMMO1 prevented viremia and reduced viral loads to nearly undetectable levels in humanized mice. AMMO1 conferred sterilizing immunity to three of four macaques challenged orally with rhesus lymphocryptovirus, the EBV ortholog that infects rhesus macaques. The infected macaque had lower plasma neutralizing activity than the protected animals. These results indicate that a vaccine capable of eliciting adequate titers of neutralizing antibodies targeting the AMMO1 epitope may protect against EBV acquisition and are therefore highly relevant to the design of an effective EBV vaccine.

An anti-EBV mAb, AMMO1, limits viral replication following challenge in humanized mice

AMMO1 cross-reacts with and neutralizes rhesus lymphocryptovirus

Adequate levels of AMMO1 prevent oral acquisition of rhLCV in macaques

Protection afforded by neutralizing antibody provides proof of concept for EBV vaccines

CD21 (Complement Receptor 2) Is the Receptor for Epstein-Barr Virus Entry into T Cells

Epstein-Barr virus (EBV) is associated with a number of T-cell diseases, including some peripheral T-cell lymphomas, hemophagocytic lymphohistiocytosis, and chronic active EBV disease. The tropism of EBV for B cells and epithelial cell infection has been well characterized, but infection of T cells has been minimally explored. We have recently shown that the EBV type 2 (EBV-2) strain has the unique ability to infect mature T cells. Utilizing an ex vivo infection model, we sought to understand the viral glycoprotein and cellular receptor required for EBV-2 infection of T cells. Here, using a neutralizing-antibody assay, we found that viral gp350 and complement receptor 2 (CD21) are required for CD3⁺ T-cell infection. Using the HB5 anti-CD21 antibody clone but not the Bly-4 anti-CD21 antibody clone, we detected expression of CD21 on both CD4⁺ and CD8⁺ T cells, with the highest expression on naive CD4 and CD8⁺ T-cell subsets. Using CRISPR to knock out CD21, we demonstrated that CD21 is necessary for EBV entry into the Jurkat T-cell line. Together, these results indicate that EBV uses the same viral glycoprotein and cellular receptor for both T- and B-cell infection.IMPORTANCE Epstein-Barr virus (EBV) has a well-described tropism for B cells and epithelial cells. Recently, we described the ability of a second strain of EBV, EBV type 2, to infect mature peripheral T cells. Using a neutralizing antibody assay, we determined that EBV uses the viral glycoprotein gp350 and the cellular protein CD21 to gain entry into mature peripheral T cells. CRISPR-Cas9 deletion of CD21 on the Jurkat T-cell line confirmed that CD21 is required for EBV infection. This study has broad implications, as we have defined a function for CD21 on mature peripheral T cells, i.e., as a receptor for EBV. In addition, the requirement for gp350 for T-cell entry has implications for EBV vaccine studies currently targeting the gp350 glycoprotein to prevent EBV-associated diseases.

A Pentavalent Epstein-Barr Virus-Like Particle Vaccine Elicits High Titers of Neutralizing Antibodies against Epstein-Barr Virus Infection in Immunized Rabbits

Primary infection with Epstein-Barr virus (EBV) is associated with acute infectious mononucleosis, whereas persistent infection is associated with chronic diseases such as autoimmune diseases and various types of cancer. Indeed, approximately 2% of all new cancer cases occurring annually worldwide are EBV-associated. Currently, there is no licensed EBV prophylactic vaccine. Selection of appropriate viral protein subunits is critical for development of an effective vaccine. Although the major EBV surface glycoprotein gp350/220 (gp350) has been proposed as an important prophylactic vaccine target, attempts to develop a potent vaccine based on gp350 alone have shown limited success in the clinic. We provide data showing that five EBV glycoproteins (gp350, gB, gp42, gH, and gL) involved in viral entry and infection can successfully be incorporated on the surface of EBV-like particles (EBV-LPs). These EBV-LPs, when administered together with aluminum hydroxide and monophosphoryl lipid A as adjuvants to New Zealand white rabbits, elicited EBV glycoprotein-specific antibodies capable of neutralizing viral infection in vitro in both B cells and epithelial cells, better than soluble gp350 ectodomain. Our findings suggest that a pentavalent EBV-LP formulation might be an ideal candidate for development as a safe and immunogenic EBV vaccine.

Utilization of complement receptors in immune cell-microbe interaction

The complement system is a major humoral component of immunity and is essential for the fast elimination of pathogens invading the body. In addition to its indispensable role in innate immunity, the complement system is also involved in pathogen clearance during the effector phase of adaptive immunity. The fastest way of killing the invader is lysis by the membrane attack complex, which is formed by the terminal components of the complement cascade. Not all pathogens are lysed however and, if opsonized by a variety of molecules, they undergo phagocytosis and disposal inside immune cells. The most important complement-derived opsonins are C1q, the first component of the classical pathway, MBL, the initiator of the lectin pathway and C3-derived activation fragments, including C3b, iC3b and C3d, which all serve as ligands for their corresponding receptors. In this review, we discuss how complement receptors are utilized by various immune cells to tackle invading microbes, or by pathogens to evade host response.

Towards Understanding KSHV Fusion and Entry

How viruses enter cells is of critical importance to pathogenesis in the host and for treatment strategies. Over the last several years, the herpesvirus field has made numerous and thoroughly fascinating discoveries about the entry of alpha-, beta-, and gamma-herpesviruses, giving rise to knowledge of entry at the amino acid level and the realization that, in some cases, researchers had overlooked whole sets of molecules essential for entry into critical cell types. Herpesviruses come equipped with multiple envelope glycoproteins which have several roles in many aspects of infection. For herpesvirus entry, it is usual that a collective of glycoproteins is involved in attachment to the cell surface, specific interactions then take place between viral glycoproteins and host cell receptors, and then molecular interactions and triggers occur, ultimately leading to viral envelope fusion with the host cell membrane. The fact that there are multiple cell and virus molecules involved with the build-up to fusion enhances the diversity and specificity of target cell types, the cellular entry pathways the virus commandeers, and the final triggers of fusion. This review will examine discoveries relating to how Kaposi's sarcoma-associated herpesvirus (KSHV) encounters and binds to critical cell types, how cells internalize the virus, and how the fusion may occur between the viral membrane and the host cell membrane. Particular focus is given to viral glycoproteins and what is known about their mechanisms of action.