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MicroRNAs (miRNAs) are a class of small non-coding RNAs involved in post-transcriptional gene regulation. Some viruses encode their own miRNAs and these are increasingly being recognized as important modulators of viral and host gene expression. Cyprinid herpesvirus 3 (CyHV-3) is a highly pathogenic agent that causes acute mass mortalities in carp (Cyprinus carpio carpio) and koi (Cyprinus carpio koi) worldwide. Here, bioinformatic analyses of the CyHV-3 genome suggested the presence of non-conserved precursor miRNA (pre-miRNA) genes. Deep sequencing of small RNA fractions prepared from in vitro CyHV-3 infections led to the identification of potential miRNAs and miRNA-offset RNAs (moRNAs) derived from some bioinformatically predicted pre-miRNAs. DNA microarray hybridization analysis, Northern blotting and stem-loop RT-qPCR were then used to definitively confirm that CyHV-3 expresses two pre-miRNAs during infection in vitro. The evidence also suggested the presence of an additional four high-probability and two putative viral pre-miRNAs. MiRNAs from the two confirmed pre-miRNAs were also detected in gill tissue from CyHV-3-infected carp. We also present evidence that one confirmed miRNA can regulate the expression of a putative CyHV-3-encoded dUTPase. Candidate homologues of some CyHV-3 pre-miRNAs were identified in CyHV-1 and CyHV-2. This is the first report of miRNA and moRNA genes encoded by members of the Alloherpesviridae family, a group distantly related to the Herpesviridae family. The discovery of these novel CyHV-3 genes may help further our understanding of the biology of this economically important virus and their encoded miRNAs may have potential as biomarkers for the diagnosis of latent CyHV-3.

Herpesviruses are ubiquitous, double-stranded DNA, enveloped viruses that establish lifelong infections and cause a range of diseases. Entry into host cells requires binding of the virus to specific receptors, followed by the coordinated action of multiple viral entry glycoproteins to trigger membrane fusion. Although the core fusion machinery is conserved for all herpesviruses, each species uses distinct receptors and receptor-binding glycoproteins. Structural studies of the prototypical herpesviruses herpes simplex virus 1 (HSV-1), HSV-2, human cytomegalovirus (HCMV) and Epstein–Barr virus (EBV) entry glycoproteins have defined the interaction sites for glycoprotein complexes and receptors, and have revealed conformational changes that occur on receptor binding. Recent crystallography and electron microscopy studies have refined our model of herpesvirus entry into cells, clarifying both the conserved features and the unique features. In this Review, we discuss recent insights into herpesvirus entry by analysing the structures of entry glycoproteins, including the diverse receptor-binding glycoproteins (HSV-1 glycoprotein D (gD), EBV glycoprotein 42 (gp42) and HCMV gH–gL–gO trimer and gH–gL–UL128–UL130–UL131A pentamer), as well gH–gL and the fusion protein gB, which are conserved in all herpesviruses.Recent crystallography and electron microscopy studies have refined our model of herpesvirus entry into cells. In this Review, Connolly, Jardetzky and Longnecker discuss recent insights into herpesvirus entry by analysing the structures of entry glycoproteins, including the diverse receptor-binding glycoproteins and conserved fusion proteins.

ObjectiveTo evaluate the risks of herpes zoster (HZ) and herpes simplex virus (HSV) infection associated with tofacitinib compared with biologic agents among patients with rheumatoid arthritis (RA).MethodsUsing health plan data from 2010 to 2014, patients with RA initiating tofacitinib or biologics with no history of HZ or HSV were identified, as were incident cases of HZ or HSV. Crude incidence rates were calculated by drug exposure. Cox proportional hazards models evaluated the adjusted association between tofacitinib and HZ, and a composite outcome of HZ or HSV.ResultsA total of 2526 patients initiating tofacitinib were compared with initiations of other biologics: anti-tumour necrosis factor (TNF) (n=42 850), abatacept (n=12 305), rituximab (n=5078) and tocilizumab (n=6967). Patients receiving tofacitinib were somewhat younger (mean age 55 years) versus those on other biologics, and somewhat less likely to use concomitant methotrexate (MTX) (39% vs 43%–56%, depending on drug). Crude incidence of HZ associated with tofacitinib was 3.87/100 patient-years (py). After multivariable adjustment, HZ risk was significantly elevated, HR 2.01 (95% CI 1.40 to 2.88) compared with abatacept. Rates and adjusted HRs for all other RA biologics were comparable with each other and abatacept. Older age, female sex, prednisone >7.5 mg/day, prior outpatient infection and greater number of hospitalisations were also associated with increased HZ risk. Incidence rates for the combined outcome were greatest for tofacitinib (7.61/100 py) and also significantly elevated after adjustment (HR=1.40, 95% CI 1.09 to 1.81).ConclusionsThe rate of zoster associated with tofacitinib was approximately double that observed in patients using biologics.

Viruses are intracellular pathogens that hijack host cell machinery and resources to replicate. Rather than being constant, host physiology is rhythmic, undergoing circadian (∼24 h) oscillations in many virus-relevant pathways, but whether daily rhythms impact on viral replication is unknown. We find that the time of day of host infection regulates virus progression in live mice and individual cells. Furthermore, we demonstrate that herpes and influenza A virus infections are enhancedwhen host circadian rhythms are abolished by disrupting the key clock gene transcription factor Bmal1. Intracellular trafficking, biosynthetic processes, protein synthesis, and chromatin assembly all contribute to circadian regulation of virus infection. Moreover, herpesviruses differentially target components of the molecular circadian clockwork. Our work demonstrates that viruses exploit the clockwork for their own gain and that the clock represents a novel target for modulating viral replication that extends beyond any single family of these ubiquitous pathogens.

Herpes simplex virus 1 (HSV-1) is the most commonly studied pathogen in the context of AD, primarily due to identification years ago of HSV-1 DNA in AD patient brains at autopsy [9,10]. De Chiara and colleagues demonstrated that recurrent reactivation of HSV-1 in a wild-type mouse model could produce hallmark AD pathology, accompanied by cognitive deficits, an intriguing result that supports the hypothesis that reactivation is critical in the connection between herpesviruses and AD. Use of any antiherpetics resulted in hazard ratios well below 1.0, indicating decreasing risk of developing dementia. First and foremost, important questions on the relationship between established risk factors of AD and pathogen infections remain to be addressed.

Background. Systemic reactivations of herpesviruses may occur in intensive care unit (ICU) patients, even in those without prior immune deficiency. However, the clinical relevance of these events is uncertain. Methods. In this study we selected patients admitted with septic shock and treated for more than 4 days from a prospectively enrolled cohort of consecutive adults in the mixed ICUs of 2 tertiary care hospitals in the Netherlands. We excluded patients who had received antiviral treatment in the week before ICU admission and those with known immunodeficiency. We studied viremia episodes with cytomegalovirus (CMV), Epstein–Barr virus (EBV), human herpesvirus 6 (HHV-6), herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), and varicella zoster virus (VZV) by weekly polymerase chain reaction in plasma. Results. Among 329 patients, we observed 399 viremia episodes in 223 (68%) patients. Viremia with CMV, EBV, HHV-6, HSV-1, HSV-2, and VZV was detected in 60 (18%), 157 (48%), 80 (24%), 87 (26%), 13 (4%), and 2 (0.6%) patients, respectively; 112 (34%) patients had multiple concurrent viremia events. Crude mortality in the ICU was 36% in this latter group compared to 19% in remaining patients (P < .01). After adjustment for potential confounders, time-dependent bias, and competing risks, only concurrent CMV and EBV reactivations remained independently associated with increased mortality (adjusted subdistribution hazard ratio, 3.17; 95% confidence interval, 1.41–7.13). Conclusions. Herpesvirus reactivations were documented in 68% of septic shock patients without prior immunodeficiency and frequently occurred simultaneously. Concurrent reactivations could be independently associated with mortality. Clinical Trials Registration. NCT01905033.

Cyprinid herpesvirus is a causative agent of a destructive disease in common and koi carp ( Cyprinus carpio ), which leads to substantial global financial losses in aquaculture industries. Among the strains of C. herpesvirus , C. herpesvirus 1 (CyHV-1) and C. herpesvirus 3 (CyHV-3) are known as highly pathogenic to carp fishes in Europe, Asia, and Africa. To date, no effective vaccine has been developed to combat these viruses. This study aimed to develop unique multi-epitope subunit vaccines targeting the CyHV-1 and CyHV-3 using a reverse vaccinology approach. The study began with a comprehensive literature review to identify the most critical proteins, which were then subjected to in silico analyses to predict highly antigenic epitopes. These analyses involved assessing antigenicity, transmembrane topology screening, allergenecity, toxicity, and molecular docking approaches. We constructed two multi-epitope-based vaccines incorporating a suitable adjuvant and appropriate linkers. It revealed that both the vaccines are non-toxic and immunogenic. The tertiary structures of the vaccine proteins were generated, refined, and validated to ensure their suitability. The binding affinity between the vaccine constructs and TLR3 and TLR5 receptors were assessed by molecular docking studies. Molecular dynamics simulations indicated that vaccine construct V1 exhibited greater stability with both TLR3 and TLR5 based on RMSD analysis. Hydrogen bond analysis revealed a stronger binding affinity between the vaccine constructs and TLR5 compared to TLR3. Furthermore, MM-PBSA analysis suggested that both vaccine constructs exhibited a better affinity for TLR5. Considering all aspects, the results suggest that in silico development of CyHV vaccines incorporating multiple epitopes holds promise for management of diseases caused by CyHV-1 and CyHV-3. However, further in vivo trials are highly recommended to validate the efficacies of these vaccines.

Key Points Herpesviruses are a ubiquitous, large, diverse family of double-stranded DNA, enveloped viruses that are capable of infecting a wide range of hosts and causing a variety of diseases. Prototypical herpesviruses are herpes simplex virus 1 (HSV-1), HSV-2 and Epstein–Barr Virus (EBV), which cause oral herpes, genital herpes and mononucleosis, respectively. Herpesviruses use common mechanisms to bind to and enter target cells through a process of virus-induced membrane fusion. Relative to other enveloped viruses, herpesviruses require a large number of glycoproteins in order to accomplish fusion. The conserved core set of glycoproteins required for entry are glycoprotein B (gB) and a heterodimer composed of gH and gL, referred to as gH–gL. Additional required glycoproteins are the receptor-binding proteins gD from HSVs and glycoprotein 42 (gp42) from EBV. The structures for each glycoprotein required for virus entry, as well as for three of the cellular receptors that bind to the virus and/or trigger fusion, are now known. EBV and HSVs infect multiple cell types through engagement with different receptors. Although the primary receptor-binding proteins of these viruses are different, fusion of HSVs and EBV with most cell types is triggered when their receptor-binding proteins bind a receptor via flexible amino-terminal extensions. A resulting conformational change is thought to trigger the viral glycoproteins that execute fusion. Viral glycoproteins that execute fusion — gB and gH–gL — are conserved within the herpesvirus family. The crystal structure of gB revealed that it is a viral fusion protein that is capable of inserting into target membranes and inducing fusion through conformational changes. The specific role of gH–gL in fusion has eluded researchers for years. Evidence suggested that it was an additional fusion protein, but the recently solved structure of HSV-2 gH–gL revealed, surprisingly, that it does not resemble any known fusion protein. A new model of herpesvirus fusion is emerging in which gH–gL acts as a regulator of gB through (gH–gL)–gB interaction. Herpesvirus fusion is a remarkably complex process. Now that the structures of all the major glycoproteins and receptors involved in herpesvirus fusion are known, they can be used for the rational design of novel attachment and fusion inhibitors against these ubiquitous human pathogens. Entry of enveloped viruses into the host cell is an intricate process. Here, Connolly and colleagues describe the different proteins of herpes simplex viruses and Epstein–Barr virus that are involved in tethering the viruses to host cells and promoting fusion of the viruses with these host cells. Herpesviruses are double-stranded DNA, enveloped viruses that infect host cells through fusion with either the host cell plasma membrane or endocytic vesicle membranes. Efficient infection of host cells by herpesviruses is remarkably more complex than infection by other viruses, as it requires the concerted effort of multiple glycoproteins and involves multiple host receptors. The structures of the major viral glycoproteins and a number of host receptors involved in the entry of the prototypical herpesviruses, the herpes simplex viruses (HSVs) and Epstein–Barr virus (EBV), are now known. These structural studies have accelerated our understanding of HSV and EBV binding and fusion by revealing the conformational changes that occur on virus–receptor binding, depicting potential sites of functional protein and lipid interactions, and identifying the probable viral fusogen.

Herpesvirus (HV) is widely distributed among cetacean populations, with the highest prevalence reported in the Mediterranean Sea. In this study, a comprehensive analysis was conducted, including epidemiological, phylogenetic, and pathological aspects, with particular emphasis on neuropathology, to better understand the impact of HV in these animals. Our results show a higher presence of HV in males compared to females, with males exhibiting a greater number of positive tissues. Additionally, adults were more frequently affected by HV infection than juveniles, with no infections detected in calves or neonates. The affected species were striped ( Stenella coeruleoalba ) and bottlenose dolphins ( Tursiops truncatus ). The highest positivity rates were observed in the genital system, cerebrum, and skin tissues. Phylogenetic analysis indicated a higher occurrence of Gammaherpesvirus (GHV) sequences but increased genetic diversity within Alphaherpesvirus (AHV). Key neuropathological features included astro-microgliosis (n = 4) and meningitis with minimal to mild perivascular cuffing (n = 2). The presence of concurrent infections with other pathogens, particularly cetacean morbillivirus (CeMV), underscores the complex nature of infectious diseases in cetaceans. However, the presence of lesions at the Central Nervous System (CNS) with molecular positivity for GHV, excluding the involvement of other potential neurotropic agents, would confirm the potential of this HV subfamily to induce neurological damage. Pathological examination identified lesions in other organs that could potentially be associated with HV, characterized by lymphoid depletion and tissue inflammation. These findings enhance our understanding of HV in odontocetes and highlight the need for ongoing research into the factors driving these infections and their broader implications.

Herpesviruses establish latent infections, and most reactivate frequently, resulting in symptoms and virus shedding in healthy individuals. In immunocompromised patients, reactivating virus can cause severe disease. Persistent EBV has been associated with several malignancies in both immunocompromised and nonimmunocompromised persons. Reactivation and shedding occur with most herpesviruses, despite potent virus-specific antibodies and T cell immunity as measured in the blood. The licensure of therapeutic vaccines to reduce zoster indicates that effective therapeutic vaccines for other herpesviruses should be feasible. However, varicella-zoster virus is different from other human herpesviruses in that it is generally only shed during varicella and zoster. Unlike prophylactic vaccines, in which the correlate of immunity is antibody function, T cell immunity is the correlate of immunity for the only effective therapeutic herpesvirus vaccine-zoster vaccine. While most studies of therapeutic vaccines have measured immunity in the blood, cellular immunity at the site of reactivation is likely critical for an effective therapeutic vaccine for certain viruses. This Review summarizes the status of therapeutic vaccines for herpes simplex virus, cytomegalovirus, and Epstein-Barr virus and proposes approaches for future development.