Asymptomatic Herpes Simplex Virus Type 1 Infection Causes an Earlier Onset and More Severe Experimental Autoimmune Encephalomyelitis

A novel multiplex real-time PCR assay for the detection of cytomegalovirus, Epstein-Barr virus, herpes simplex virus 1/2 and strategies for application to blood screening

A multiplex real-time PCR has been developed to simultaneously detect transfusion-transmissible pathogens cytomegalovirus, Epstein-Barr virus and herpes simplex virus, as well as to provide sample quality testing, for the conserved regions of the cytomegalovirus UL123 gene, the Epstein-Barr virus BKRF1 gene, and the herpes simplex virus 1/2 UL30 gene, tested on 500 blood donors and 320 transfusion recipients. The laboratory sensitivities for all 3 pathogens were 100 copies/μL. Compared to the commercial real-time PCR reference kit, the multiplex real-time PCR assay for the detection of CMV, EBV and HSV presented 100% consistency. In 820 whole blood samples, the multiplex real-time PCR assay identified 34 (4.15%) positive for CMV DNA, 15 (1.83%) positive for EBV DNA, and 6 (0.73%) positive for HSV DNA. For blood transfusions in high-risk groups, whole blood herpes virus test should be included in the spectrum of pathogen testing for blood donors and recipients.

The association between various viral infections and multiple sclerosis: An umbrella review on systematic review and meta-analysis

Multiple Sclerosis (MS) is one of the immune-mediated demyelinating disorders. Multiple components, including the environment and genetics, are possible factors in the pathogenesis of MS. Also, it can be said that infections are a key component of the host's response to MS development. Finally, we evaluated the relationship between different pathogens and MS disease in this umbrella research. We systematically collected and analysed multiple meta-analyses focused on one particular topic. We utilised the Scopus, PubMed, and Web of Science databases starting with inception until 30 May 2023. The methodological quality of the analysed meta-analysis has been determined based on Assessing the Methodological Quality of Systematic Reviews 2 and Grade, and graph construction and statistical analysis were conducted using Comprehensive Meta-Analysis. The Confidence Interval of effect size was 95% in meta-analyses, and p < 0.05 indicated a statistically meaningful relationship. The included studies evaluated the association between MS and 12 viruses containing SARS-CoV-2, Epstein-Barr virus (EBV), Hepatitis B virus, varicella-zoster virus (VZV), human herpesvirus 6 (HHV-6), HHV-7, HHV-8, HSV-1, HSV-2, Cytomegalovirus, Human Papillomavirus, and influenza. SARS-CoV-2, with a 3.74 odds ratio, has a significantly more potent negative effect on MS among viral infections. After that, EBV, HHV-6, HSV-2, and VZV, respectively, with 3.33, 2.81, 1.76, and 1.72 odds ratios, had a significantly negative relationship with MS (p < 0.05). Although the theoretical evidence mostly indicates that EBV has the greatest effect on MS, recent epidemiological studies have challenged this conclusion and put forward possibilities that SARS-CoV-2 is the culprit. Hence, it was necessary to investigate the effects of SARS-CoV-2 and EBV on MS.

Heme Oxygenase-1 Expression in Dendritic Cells Contributes to Protective Immunity against Herpes Simplex Virus Skin Infection

Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) infections are highly prevalent in the human population and produce mild to life-threatening diseases. These viruses interfere with the function and viability of dendritic cells (DCs), which are professional antigen-presenting cells that initiate and regulate the host's antiviral immune responses. Heme oxygenase-1 (HO-1) is an inducible host enzyme with reported antiviral activity against HSVs in epithelial cells and neurons. Here, we sought to assess whether HO-1 modulates the function and viability of DCs upon infection with HSV-1 or HSV-2. We found that the stimulation of HO-1 expression in HSV-inoculated DCs significantly recovered the viability of these cells and hampered viral egress. Furthermore, HSV-infected DCs stimulated to express HO-1 promoted the expression of anti-inflammatory molecules, such as PDL-1 and IL-10, and the activation of virus-specific CD4⁺ T cells with regulatory (Treg), Th17 and Treg/Th17 phenotypes. Moreover, HSV-infected DCs stimulated to express HO-1 and then transferred into mice, promoted the activation of virus-specific T cells and improved the outcome of HSV-1 skin infection. These findings suggest that stimulation of HO-1 expression in DCs limits the deleterious effects of HSVs over these cells and induces a favorable virus-specific immune response in the skin against HSV-1.

Is there a role for herpes simplex virus type 1 in multiple sclerosis?

Numerous studies relate the onset and severity of multiple sclerosis (MS) with viral infections. Herpes simplex virus type 1 (HSV-1), which is neurotropic and highly prevalent in the brain of healthy individuals, has been proposed to relate to MS. Here, we review and discuss the reported connections between HSV-1 and MS.

Understanding global changes of the mouse brain proteome after vaginal infection with HSV-2 using a label-free shotgun approach

Herpes simplex virus type 2 (HSV-2) is a common human pathogen that establishes lifelong latency in neurons of the nervous system. The number of severe central nervous system infections caused by the virus has increased recently. However, the pathogenesis of HSV-2 infection in the nervous system is not fully understood. Here, we demonstrated global proteomic changes in the brain tissue in BALB/c mice vaginally infected with HSV-2. Data are available via ProteomeXchange with identifier PXD034186. A total of 249 differentially expressed proteins were identified in infected brain tissue. The GO and KEGG enrichment analysis of these proteins indicated that they were mainly involved in the regulation of synapse formation and synaptic excitability. In addition, genes affecting autophagy, the development of other neurodegenerative diseases, and signaling pathways relevant to other neurologic diseases were identified. Additional experiments, comparing the brain tissue of asymptomatic and symptomatic mice showed a differential expression of proteins involved in synapse formation and synaptic transmission. Others were involved in autophagy, addiction, and signaling pathways of other neurologic diseases. These results suggest that changes in synaptic structure and function, as well as autophagy, may be related to the development of neurologic abnormalities that follow HSV-2 infection. We also identified a protein GluN2A encoded by Grin2a was continuously expressed at high levels after infection. We propose that GluN2A may be a key molecule in the pathogenesis of HSV-2-induced neurologic diseases.

Mendelian Randomization Analysis Suggests No Associations of Herpes Simplex Virus Infections With Multiple Sclerosis

Previous studies have suggested an association between infection with herpes simplex virus (HSV) and liability to multiple sclerosis (MS), but it remains largely unknown whether the effect is causal. We performed a two-sample Mendelian randomization (MR) study to explore the relationship between genetically predicted HSV infection and MS risk. Genetic instrumental variables for diagnosed infections with HSV (p < 5 × 10^–6) were retrieved from the FinnGen study, and single nucleotide polymorphisms associated with circulating immunoglobulin G (IgG) levels of HSV-1 and HSV-2 and corresponding summary-level statistics of MS were obtained from genome-wide association studies of the European-ancestry. Inverse-variance weighted MR was employed as the primary method and multiple sensitivity analyses were performed. Genetically proxied infection with HSV was not associated with the risk of MS (odds ratio [OR], 0.96; 95% confidence interval [CI], 0.90–1.02; p = 0.22) per one-unit increase in log-OR of herpes viral infections. MR results provided no evidence for the relationship between circulating HSV-1 IgG levels and MS risks (OR = 0.91; 95% CI, 0.81–1.03; p = 0.37), and suggested no causal effect of HSV-2 IgG (OR = 1.04; 95% CI, 0.96–1.13; p = 0.32). Additional sensitivity analyses confirmed the robustness of these null findings. The MR study did not support the causal relationship between genetic susceptibly to HSV and MS in the European population. Further studies are still warranted to provide informative knowledge, and triangulating evidence across multiple lines of evidence are necessary to plan interventions for the treatment and prevention of MS.

Crosstalk Between Epithelial Cells, Neurons and Immune Mediators in HSV-1 Skin Infection

Herpes simplex virus type 1 (HSV-1) infection is highly prevalent in humans, with approximately two-thirds of the world population living with this virus. However, only a fraction of those carrying HSV-1, which elicits lifelong infections, are symptomatic. HSV-1 mainly causes lesions in the skin and mucosae but reaches the termini of sensory neurons innervating these tissues and travels in a retrograde manner to the neuron cell body where it establishes persistent infection and remains in a latent state until reactivated by different stimuli. When productive reactivations occur, the virus travels back along axons to the primary infection site, where new rounds of replication are initiated in the skin, in recurrent or secondary infections. During this process, new neuron infections occur. Noteworthy, the mechanisms underlying viral reactivations and the exit of latency are somewhat poorly understood and may be regulated by a crosstalk between the infected neurons and components of the immune system. Here, we review and discuss the immune responses that occur at the skin during primary and recurrent infections by HSV-1, as well as at the interphase of latently-infected neurons. Moreover, we discuss the implications of neuronal signals over the priming and migration of immune cells in the context of HSV-1 infection.