Journal of Virology最新文献

Emerging tick-borne orthonairovirus infections pose a growing global concern, with limited understanding of the viral ovarian tumor-like cysteine proteases (vOTUs) encoded by novel orthonairoviruses. These vOTUs, a group of deubiquinylases (DUBs), disrupt the innate immune response. Yezo virus (YEZV), a recently discovered pathogenic orthonairovirus, was first reported in Japan in 2021. In this study, we successfully isolated and identified YEZV and a new orthonairovirus, Jiànchuān tick virus (JCTV), from Ixodes persulcatus and Haemaphysalis montgomeryi ticks, respectively, in China. We found that the vOTU domains encoded by YEZV and JCTV exhibited both DUB and deISGylase activities, though with potentially less broad deISGylation compared to that of Crimean-Congo hemorrhagic fever virus (CCHFV) during natural infection. Phylogenetic analysis of global vOTUs, including 83 new sequences, revealed a high diversity of this domain. Interestingly, retrospective screening of tick-bite patients from 2012 to 2016 in northeastern China traced YEZV infections as far back as 2012, identifying four cases. Additionally, YEZV primarily infected I. persulcatus (31.4%) and Dermacentor nuttalli (10.5%) in northern China, while JCTV exhibited high infection rates in H. montgomeryi (81.3%) in southern China. In summary, our work emphasizes the active surveillance of orthonairovirus infections and the imperative need for the development of vOTU domain-targeted anti-virals, offering potential therapeutic solutions for a broad spectrum of orthonairoviruses.IMPORTANCEThe vOTUs, a group of DUBs, mimic the functions of host DUBs to enhance viral infectivity and may serve as potential drug targets. vOTUs from different orthonairoviruses exhibit distinct preferences toward ubiquitin (Ub) and ubiquitin-like protein interferon stimulated gene 15 (ISG15). In this study, we investigated the deubiquitinase and deISGylase functions of various orthonairoviral vOTUs using both an overexpression system and natural viral infections in vitro. Our findings illustrate that the vOTUs from YEZV and JCTV can cleave both Ub and ISG15 in an overexpression system, but these viruses exhibit potentially narrower deISGylation capacity than CCHFV during natural infection. This suggests that the diversity of vOTUs may have a potential relationship with the pathogenesis.

One key determinant of HIV-1 latency reversal is the activation of the viral long terminal repeat (LTR) by cellular transcription factors such as NF-κB and AP-1. Interestingly, the activity of these two transcription factors can be modulated by glucocorticoid receptors (GRs). Furthermore, the HIV-1 genome contains multiple binding sites for GRs. We therefore hypothesized that glucocorticoids and other GR modulators may influence HIV-1 latency and reactivation. To investigate how GR signaling affects latent HIV-1 reservoirs, we assembled a representative panel of GR modulators including natural steroidal agonists, selective and non-selective GR modulators, and clinically approved GR-modulating drugs. The effects of these compounds on HIV-1 reactivation were assessed using latently HIV-1-infected cell lines and primary cells, as well as reporter assays that monitored GR and LTR activities. We found that AZD9567 (Mizacorat), a non-steroidal partial GR agonist, reactivates latent HIV-1 in both lymphoid and myeloid cell lines and primary CD4+ T cells. Conversely, the GR antagonist mifepristone suppresses HIV-1 LTR-driven gene expression. Mechanistic analyses revealed that AZD9567-mediated reactivation partially depends on both GR and AP-1 binding sites in the LTR. In summary, we, here, identify the GR modulator AZD9567 as novel latency-reversing agent that activates LTR-driven gene expression, which may aid in advancing current shock-and-kill approaches in the treatment of HIV-1 infection.IMPORTANCELatently infected cells of people living with HIV are constantly exposed to fluctuating levels of glucocorticoid hormones such as cortisol. In addition, many HIV-infected individuals regularly take corticosteroids as anti-inflammatory drugs. Although corticosteroids are known to affect the activity of the viral long terminal repeat (LTR) promoter and influence ongoing HIV-1 replication, relatively little is known about the effect of corticosteroid hormones and other glucocorticoid receptor (GR) modulators on latent HIV-1. By systematically comparing natural and synthetic GR modulators, we, here, identify a first first-in-class, oral, partial GR agonist that reactivates latent HIV-1 from different cell types. This drug, AZD9567, was previously tested in clinical trials for rheumatoid arthritis. Mutational analyses shed light on the underlying mode of action and revealed transcription factor binding sites in the HIV-1 LTR that determine responsiveness to AZD9567.

The outcomes of retreatment patients infected with hepatitis C virus genotype 3, cirrhosis, with velpatasvir may be affected by treatment failure with velpatasvir. The efficacy of SOF+GLE/PIB+RIB 16-24 weeks of treatment has been shown. The presence of NS5A resistance-associated substitution mutations, including Y93H, and the number and regimens of the past failed therapy do not influence the likelihood of achieving sustained virological response. When velpatasvir treatment fails, pibrentasvir should be used as the first choice for retreatment.

Pseudorabies virus (PRV) is a porcine neurotropic alphaherpesvirus that infects peripheral tissues of its host, spreads into the nervous system, and establishes a life-long latency in neuronal cells. During productive infection, PRV replicates rapidly and causes pseudorabies or Aujeszky's disease. Reactivation from latent infection in the nervous system may lead to anterograde axonal transport of progeny virions, leading to recurrent infection of the epithelial layer and virus spread. Dexamethasone (DEX), a member of the glucocorticoid family that is widely used in clinical treatment as a high-efficiency glucocorticoid receptor (GR) agonist, is known to trigger reactivation of alphaherpesviruses like PRV and the closely related bovine alphaherpesvirus 1. In the current study, two cell type-dependent distinct regulatory mechanisms of glucocorticoid during PRV infection are described. In neuron-like cells, DEX upregulates expression of PRV IE180 and promotes viral productive infection. In addition, we found that GR activates the IE180 promoter by binding multiple GR response elements. The amino acids A465, P631, and I634 in GR were found to be critical for IE180 promoter activation. The impact of DEX on PRV productive infection in epithelial cells was also investigated. Interestingly, DEX was found to downregulate IE180 expression and suppress PRV infection in epithelial cells. Mechanistically, in epithelial cells, activation of the IE180 promoter by the VP16/Oct-1 (octamer-binding transcription factor 1) complex was suppressed by DEX-mediated degradation of Oct-1 in epithelial cells. In summary, our work reveals two distinct, cell type-dependent biological functions of glucocorticoid during PRV infection in neuron-like and epithelial cells, respectively.IMPORTANCEPseudorabies virus (PRV) can infect mucosal epithelium and the peripheral nervous system of its host, resulting in acute infection in epithelial cells and neuronal cells. In this study, we describe that glucocorticoid promotes PRV replication in neuron-like cells while it suppresses productive infection in epithelial cells through distinct regulations of the viral transactivator IE180, thereby revealing a cell type-dependent regulatory mechanism of glucocorticoid on PRV infection. Therefore, our findings provide a new perspective on the role of glucocorticoids during PRV infection.

NF-κB essential modulator (NEMO) is critically involved in the induction of interferons (IFNs) and pro-inflammatory cytokines. Hepatitis A virus (HAV) 3C protease was recently identified to cleave NEMO in non-hepatic cells. This study aimed at understanding efficiency and function of HAV 3C-mediated NEMO cleavage in hepatocytes. HAV 3C protease and its precursor 3CD strongly affected NEMO abundance in ectopic expression models, which was not observed in HAV replicon cells and upon HAV infection. Using a cleavage-resistant NEMO mutant, we found that specific cleavage by 3C only marginally contributed to NEMO degradation, whereas the magnitude of the effect was due to cytotoxic effects induced by 3C activity. Cleavage efficiency generally did not suffice to disrupt the type I IFN or NF-κB signaling pathways. Knockout of NEMO indeed abrogated both pathways, whereas efficient knockdown had limited the impact on NEMO-mediated signaling, suggesting that low levels of NEMO are sufficient to maintain antiviral responses in hepatocytes. NEMO cleavage was barely detectable in a cell line harboring a persistent HAV replicon or in HAV-infected cells. HAV infection induced a robust innate immune response, which was not affected by efficient knockdown of NEMO, arguing for a limited potential contribution of NEMO cleavage to innate immune counteraction. Overall, our data suggest that HAV 3C is capable of partially cleaving NEMO as reported. However, since minute expression levels of NEMO were sufficient for induction of innate immunity, inefficient NEMO cleavage by HAV is unlikely to contribute to dampening of innate immune responses in hepatocytes.IMPORTANCEHepatitis A virus (HAV) establishes acute infections of the liver, which are always cleared, while a number of mechanisms have been identified contributing to immune escape. Among those, proteolytic cleavage of NF-κB essential modulator (NEMO) by HAV has been suggested to counteract innate immune responses. This study demonstrates that the HAV 3C protease cleaves NEMO inefficiently and does not result in substantial disruption of antiviral signaling. Importantly, NEMO remains capable of inducing an effective immune response in hepatocytes even at low expression levels. Our findings suggest a limited role for NEMO cleavage in HAV's interaction with host immunity and call for a revision of our understanding of HAV counteraction mechanisms.

The unprecedented sequencing efforts during the COVID-19 pandemic paved the way for genomic surveillance to become a powerful tool for monitoring the evolution of circulating viruses. Herein, we discuss how a state-of-the-art artificial intelligence approach called protein language models (pLMs) can be used for effectively analyzing pathogen genomic data. We highlight examples of pLMs applied to predicting viral properties and evolution and lay out a framework for integrating pLMs into genomic surveillance pipelines.

Tomato is an important crop worldwide, but groundnut bud necrosis virus (GBNV) often hampers its growth. This study investigates the antiviral potential of bacterial endophytes, including Brucella melitensis CNEB54, Bacillus licheniformis CNEB4, Bacillus velezensis CNEB26, and Bacillus vallismortis BAVE5 against GBNV, as well as their ability to enhance immunity and growth in tomato. All four bacterial isolates demonstrated a significant delay in GBNV symptom development 10 days post-inoculation, with disease incidence ranging from 18% to 36% compared to 84% in control. DAC-ELISA results indicated a noteworthy reduction in virus titer (0.32-0.96 OD) in treated tomato plants versus the control (3.26 OD). In addition, qPCR analysis revealed decreased viral copy numbers in plants treated with bacterial endophytes (1.3-3.1 × 10⁵) as against in untreated inoculated control (2.4 × 10⁶). Furthermore, these endophytes upregulated the expression of defense-associated genes, such as MAPKK1, PAL, PPO, LOX1, JAR1, and PDF 1.2. Field experiments with the application of B. melitensis and B. velezensis exhibited improved growth, with an average plant height of 123.70 cm, 14.87 flowers per plant, and a fruit weight of 549.3 g per plant, with a disease incidence of 18.1%. In comparison, the untreated control plants only reached a height of 104.73 cm, produced 11.17 flowers per plant, and yielded 267 g of fruit per plant, with a disease incidence of 30.1%. These findings strongly support the use of bacterial endophytes to reduce disease incidence and severity, enhance plant immunity and promote plant growth, resulting in overall crop productivity in sustainable agriculture.IMPORTANCEThe infection of GBNV in crops such as tomatoes, peanuts, and pulses leads to significant yield loss. Applying insecticides to control vector populations, can limit the spread of viruses carried by these vectors. The present study envisages a novel strategy to combat GBNV, with the help of bacterial endophytes. These bacterial endophytes have tremendously reduced the symptom expression of GBNV, induced the expression of defense genes during the tri-trophic interaction and promoted plant growth in tomatoes under field conditions. Hence, these bacteria are identified to be involved in immunity boosting, viral suppression and growth promotion.

Due to the importance of post-translational modification (PTM) in cellular function, viruses have evolved to both take advantage of and be susceptible to such modification. Adenovirus encodes a multifunctional protein called protein VII, which is packaged with the viral genome in the core of virions and disrupts host chromatin during infection. Protein VII has several PTMs whose addition contributes to the subnuclear localization of protein VII. Here, we used mutant viruses that abrogate or mimic these PTMs on protein VII to interrogate their impact on protein VII function during adenovirus infection. We discovered that acetylation of the lysine in positions 2 or 3 (K2 or K3) is deleterious during early infection as mutation to alanine led to greater intake of protein VII and viral DNA to the nucleus and enhanced early gene expression. Furthermore, we determined that protein VII is acetylated at alternative residues late during infection which may compensate for the mutated sites. Lastly, due to the role of the early viral protein E1A in viral gene activation, we investigated the interaction between protein VII and E1A and demonstrated that protein VII interacts with E1A through a chromatin-mediated interaction. Together, these results emphasize that the complexity of virus-host interactions is intimately tied to post-translational modification.

Importance: Adenoviruses are ubiquitous human pathogens that cause a variety of diseases, such as respiratory infections, gastroenteritis, and conjunctivitis. While often viewed as a self-limiting infection in healthy individuals, adenoviruses are particularly harmful to immunocompromised patients. Here, we investigate the functional role of post-translational modifications (PTMs) on an essential adenovirus core protein, protein VII, describing how they regulate its function during the early and late stages of infection. Our study focuses on how specific PTMs on protein VII influence transcription, localization, and interactions with other proteins, highlighting how PTMs are employed by viruses to alter protein function.

Coronaviruses (CoVs) encode non-structural proteins (nsp's) 1-16, which assemble to form replication-transcription complexes that function in viral RNA synthesis. All CoVs encode a proofreading 3'-5' exoribonuclease in non-structural protein 14 (nsp14-ExoN) that mediates proofreading and high-fidelity replication and is critical for other roles in replication and pathogenesis. The in vitro enzymatic activity of nsp14-ExoN is enhanced in the presence of the cofactor nsp10. We introduced alanine substitutions in nsp14 of murine hepatitis virus (MHV) at the nsp14-nsp10 interface and recovered mutant viruses with a range of impairments in replication and in vitro biochemical exonuclease activity. Two of these substitutions, nsp14 K7A and D8A, had impairments intermediate between wild type-MHV nsp14 and the known ExoN(-) D89A/E91A nsp14 catalytic inactivation mutant. All introduced nsp14-nsp10 interface alanine substitutions impaired in vitro exonuclease activity. Passage of the K7A and D8A mutant viruses selected second-site non-synonymous mutations in nsp14 associated with improved mutant virus replication and exonuclease activity. These results confirm the essential role of the nsp14-nsp10 interaction for efficient enzymatic activity and virus replication, identify proximal and long-distance determinants of nsp14-nsp10 interaction, and support targeting the nsp14-nsp10 interface for viral inhibition and attenuation.IMPORTANCECoronavirus replication requires assembly of a replication transcription complex composed of nsp's, including polymerase, helicase, exonuclease, capping enzymes, and non-enzymatic cofactors. The coronavirus nsp14 exoribonuclease mediates several functions in the viral life cycle including genomic and subgenomic RNA synthesis, RNA recombination, RNA proofreading and high-fidelity replication, and native resistance to many nucleoside analogs. The nsp-14 exonuclease activity in vitro requires the non-enzymatic cofactor nsp10, but the determinants and importance of the nsp14-nsp10 interactions during viral replication have not been defined. Here we show that for the coronavirus murine hepatitis virus, nsp14 residues at the nsp14-nsp10 interface are essential for efficient viral replication and in vitro exonuclease activity. These results shed new light on the requirements for protein interactions within the coronavirus replication transcription complex, and they may reveal novel non-active-site targets for virus inhibition and attenuation.