Host DNA Demethylation Induced by DNMT1 Inhibition Up-Regulates Antiviral OASL Protein during Influenza a Virus Infection

DNMT3B inhibits PCV2 replication via targeting TMEM37 to regulate Ca2 + influx in PK15 cells

Porcine circovirus type 2 (PCV2) is the main pathogen causing postweaning multisystemic wasting syndrome, which leads to enormous losses for porcine industry. However, the regulatory mechanism of PCV2 replication in host cells remains not been clarified. Here, pig DNMT3B was identified as be a host regulator associated with PCV2 infection via RNA-seq analysis. We demonstrated that upregulation of DNMT3B expression can effectively inhibit PCV2 replication in PK15 cells. Besides, TMEM37 acts as a key downstream target of DNMT3B in PCV2-infected PK15 cells. TMEM37 knockdown significantly slowed Ca2+ influx, and thus inhibited PCV2 replication. Taken together, DNMT3B is required for the PCV2-based infection regulation in host cells. Our findings indicated that DNMT3B inhibits PCV2 replication via targeting TMEM37 to regulate Ca2+ influx in PK15 cells, which offering a theoretical foundation for the use of this gene as a key biomarker for breeding strategies seeking to improve porcine disease resistance.

Harnessing Epigenetics: Innovative Approaches in Diagnosing and Combating Viral Acute Respiratory Infections

Acute respiratory infections (ARIs) caused by viruses such as SARS-CoV-2, influenza viruses, and respiratory syncytial virus (RSV), pose significant global health challenges, particularly for the elderly and immunocompromised individuals. Substantial evidence indicates that acute viral infections can manipulate the host's epigenome through mechanisms like DNA methylation and histone modifications as part of the immune response. These epigenetic alterations can persist beyond the acute phase, influencing long-term immunity and susceptibility to subsequent infections. Post-infection modulation of the host epigenome may help distinguish infected from uninfected individuals and predict disease severity. Understanding these interactions is crucial for developing effective treatments and preventive strategies for viral ARIs. This review highlights the critical role of epigenetic modifications following viral ARIs in regulating the host's innate immune defense mechanisms. We discuss the implications of these modifications for diagnosing, preventing, and treating viral infections, contributing to the advancement of precision medicine. Recent studies have identified specific epigenetic changes, such as hypermethylation of interferon-stimulated genes in severe COVID-19 cases, which could serve as biomarkers for early detection and disease progression. Additionally, epigenetic therapies, including inhibitors of DNA methyltransferases and histone deacetylases, show promise in modulating the immune response and improving patient outcomes. Overall, this review provides valuable insights into the epigenetic landscape of viral ARIs, extending beyond traditional genetic perspectives. These insights are essential for advancing diagnostic techniques and developing innovative treatments to address the growing threat of emerging viruses causing ARIs globally.

Immune responses to avian influenza viruses in chickens

Chickens are a key species in both the manifestation of avian influenza and the potential for zoonotic transmission. Avian influenza virus (AIV) infection in chickens can range from asymptomatic or mild disease with low pathogenic AIVs (LPAIVs) to systemic fatal disease with high pathogenic AIVs (HPAIVs). During AIV infection in chickens, Toll-like receptor 7 and melanoma differentiation-associated gene 5 are upregulated to detect the single-stranded ribonucleic acid genomes of AIV, triggering a signaling cascade that produces interferons (IFNs) and pro-inflammatory cytokines. These inflammatory mediators induce the expression of antiviral proteins and recruit immune system cells, such as macrophages and dendritic cells, to the infection site. AIV evades these antiviral responses primarily through its non-structural protein 1, which suppresses type I IFNs, influencing viral pathogenicity. The uncontrolled release of pro-inflammatory cytokines may contribute to the pathogenicity and high mortality associated with HPAIV infections. AIV modulates apoptosis in chicken cells to enhance its replication, with variations in apoptosis pathways influenced by viral strain and host cell type. The presentation of AIV antigens to T and B cells leads to the production of neutralizing antibodies and the targeted destruction of infected cells by CD8+ T cells, respectively, which enhances protection and establishes immunological memory. This review explores the diverse innate and adaptive immune responses in chickens to different AIVs, focusing on the dynamics of these responses relative to protection, susceptibility, and potential immunopathology. By understanding these immune mechanisms, informed strategies for controlling AIV infection and improving chicken health can be developed.

Research progress on miRNAs function in the interaction between human infectious viruses and hosts: A review

MicroRNAs (miRNAs) represent a class of non-coding small RNAs that are prevalent in eukaryotes, typically comprising approximately 22 nucleotides, and have the ability to post-transcriptionally regulate gene expression. miRNAs exhibit diverse types and functions, with mechanisms of action that include cell differentiation, proliferation, apoptosis, and regulation of signaling pathways. Both viruses and their hosts can encode miRNAs, which serve as crucial effector molecules in the complex interaction between viruses and host cells. Host miRNAs can either directly interact with the virus genome to inhibit virus replication or facilitate virus replication by providing necessary substances. Viral miRNAs can directly bind to host mRNAs, thereby influencing translation efficiency, suppressing the immune response, and ultimately enhancing virus replication. This article comprehensively reviews the roles of miRNAs in virus-host interactions, aiming to provide valuable insights into viral pathogenic mechanisms and potential therapeutic approaches.

Transcriptome analysis of Vero cells infected with attenuated vaccine strain CDV-QN-1

To better understand the interaction between attenuated vaccines and host antiviral responses, we used bioinformatics and public transcriptomics data to analyze the immune response mechanisms of host cells after canine distemper virus (CDV) infection in Vero cells and screened for potential key effector factors. In this study, CDV-QN-1 infect with Vero cells at an MOI of 0.5, and total RNA was extracted from the cells 24 h later and reverse transcribed into cDNA. Transcriptome high-throughput sequencing perform using Illumina. The results showed that 438 differentially expressed genes were screened, of which 409 were significantly up-regulated and 29 were significantly down-regulated. Eight differentially expressed genes were randomly selected for RT-qPCR validation, and the change trend was consistent with the transcriptomics data. GO and KEGG analysis of differentially expressed genes revealed that most of the differentially expressed genes in CDV-QN-1 infection in the early stage were related to immune response and antiviral activity. The enriched signaling pathways mainly included the interaction between cytokines and cytokine receptors, the NF-kappa B signaling pathway, the Toll-like receptor signaling pathway, and the NOD-like receptor signaling pathway. This study provides a foundation for further exploring the pathogenesis of CDV and the innate immune response of host cells in the early stage of infection.

Influenza Virus Host Restriction Factors: The ISGs and Non-ISGs

Influenza virus has been one of the most prevalent and researched viruses globally. Consequently, there is ample information available about influenza virus lifecycle and pathogenesis. However, there is plenty yet to be known about the determinants of influenza virus pathogenesis and disease severity. Influenza virus exploits host factors to promote each step of its lifecycle. In turn, the host deploys antiviral or restriction factors that inhibit or restrict the influenza virus lifecycle at each of those steps. Two broad categories of host restriction factors can exist in virus-infected cells: (1) encoded by the interferon-stimulated genes (ISGs) and (2) encoded by the constitutively expressed genes that are not stimulated by interferons (non-ISGs). There are hundreds of ISGs known, and many, e.g., Mx, IFITMs, and TRIMs, have been characterized to restrict influenza virus infection at different stages of its lifecycle by (1) blocking viral entry or progeny release, (2) sequestering or degrading viral components and interfering with viral synthesis and assembly, or (3) bolstering host innate defenses. Also, many non-ISGs, e.g., cyclophilins, ncRNAs, and HDACs, have been identified and characterized to restrict influenza virus infection at different lifecycle stages by similar mechanisms. This review provides an overview of those ISGs and non-ISGs and how the influenza virus escapes the restriction imposed by them and aims to improve our understanding of the host restriction mechanisms of the influenza virus.

Epigenetic Control of Innate Immunity: Consequences of Acute Respiratory Virus Infection

Infections caused by acute respiratory viruses induce a systemic innate immune response, which can be measured by the increased levels of expression of inflammatory genes in immune cells. There is growing evidence that these acute viral infections, alongside transient transcriptomic responses, induce epigenetic remodeling as part of the immune response, such as DNA methylation and histone modifications, which might persist after the infection is cleared. In this article, we first review the primary mechanisms of epigenetic remodeling in the context of innate immunity and inflammation, which are crucial for the regulation of the immune response to viral infections. Next, we delve into the existing knowledge concerning the impact of respiratory virus infections on the epigenome, focusing on Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Influenza A Virus (IAV), and Respiratory Syncytial Virus (RSV). Finally, we offer perspectives on the potential consequences of virus-induced epigenetic remodeling and open questions in the field that are currently under investigation.