mBio最新文献

{"title":"<i>Bordetella</i> adenylate cyclase toxin elicits chromatin remodeling and transcriptional reprogramming that blocks differentiation of monocytes into macrophages.","authors":"Jawid Nazir Ahmad, Martin Modrak, Marketa Fajfrova, Blanca Martin-Borja Sotoca, Oldrich Benada, Peter Sebo","doi":"10.1128/mbio.00138-25","DOIUrl":"10.1128/mbio.00138-25","url":null,"abstract":"<p><p><i>Bordetella pertussis</i> infects human upper airways and deploys an array of immunosuppressive virulence factors, among which the adenylate cyclase toxin (CyaA) plays a prominent role in disarming host phagocytes. CyaA binds the complement receptor-3 (CR3 aka α_Mβ₂ integrin CD11b/CD18 or Mac-1) of myeloid cells and delivers into their cytosol an adenylyl cyclase enzyme that hijacks cellular signaling through unregulated conversion of cytosolic ATP to cAMP. We found that the action of as little CyaA as 22 pM (4 ng/mL) blocks macrophage colony-stimulating factor (M-CSF)-driven transition of migratory human CD14⁺ monocytes into macrophages. Global transcriptional profiling (RNAseq) revealed that exposure of monocytes to 22 pM CyaA for 40 hours in culture with 20 ng/mL of M-CSF led to upregulation of genes that exert negative control of monocyte to macrophage differentiation (e.g., <i>SERPINB2, DLL1,</i> and <i>CSNK1E</i>). The sustained CyaA action yielded downregulation of numerous genes involved in processes crucial for host defense, such as myeloid cell differentiation, chemotaxis of inflammatory cells, antigen presentation, phagocytosis, and bactericidal activities. CyaA-elicited signaling also promoted deacetylation and trimethylation of lysines 9 and 27 of histone 3 (H3K9me3 and H3K27me3) and triggered the formation of transcriptionally repressive heterochromatin patches in the nuclei of CyaA-exposed monocytes. These effects were partly reversed by the G9a methyltransferase inhibitor UNC 0631 and by the pleiotropic HDAC inhibitor Trichostatin-A, revealing that CyaA-elicited epigenetic alterations mediate transcriptional reprogramming of monocytes and play a role in CyaA-triggered block of monocyte differentiation into bactericidal macrophage cells.IMPORTANCETo proliferate on host airway mucosa and evade elimination by patrolling sentinel cells, the whooping cough agent <i>Bordetella pertussis</i> produces a potently immunosubversive adenylate cyclase toxin (CyaA) that blocks opsonophagocytic killing of bacteria by phagocytes like neutrophils and macrophages. Indeed, chemotactic migration of CD14⁺ monocytes to the infection site and their transition into bactericidal macrophages, thus replenishing the exhausted mucosa-patrolling macrophages, represents one of the key mechanisms of innate immune defense to infection. We show that the cAMP signaling action of CyaA already at a very low toxin concentration triggers massive transcriptional reprogramming of monocytes that is accompanied by chromatin remodeling and epigenetic histone modifications, which block the transition of migratory monocytes into bactericidal macrophage cells. This reveals a novel layer of toxin action-mediated hijacking of functional differentiation of innate immune cells for the sake of mucosal pathogen proliferation and transmission to new hosts.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0013825"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143657621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geographic divergence of methicillin-resistant <i>Staphylococcus aureus</i> ST5-SCC<i>mec</i>I in the aftermath of a major earthquake and tsunami: impact of a plasmid harboring heavy metal resistance genes.","authors":"Jose R W Martínez, Manuel Alcalde-Rico, Estefanía Jara-Videla, Jinnethe Reyes, Lina P Carvajal, Sandra Rincon, Rafael Ríos, Lorena Diaz, Ana Quesille-Villalobos, Roberto Riquelme-Neira, Lina Rivas, Ahmed M Moustafa, Blake Hanson, Eduardo A Undurraga, Jorge Olivares-Pacheco, Patricia García, Rafael Araos, Paul J Planet, César A Arias, Jose M Munita","doi":"10.1128/mbio.03669-24","DOIUrl":"10.1128/mbio.03669-24","url":null,"abstract":"<p><p>Methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) is a major public health menace. The global spread of MRSA is characterized by successive waves of epidemic clones dominating specific geographical regions. The acquisition of genes encoding resistance to heavy metals (HMRGs) is thought to be a key feature in the geographic divergence of MRSA. However, the cause-effect relationship between the presence of HMRGs and the divergence of MRSA clones remains to be clarified. In this study, we assessed the role that HMRGs may have played in the evolutionary divergence of the MRSA ST5-SCC<i>mec</i>I lineage in Latin America. We conducted a genomic characterization of 113 MRSA clinical isolates from six Latin American healthcare centers, including 53 isolates collected from two cities in Chile (Santiago and Concepción). We found a plasmid (pSCL4752) harboring arsenic, cadmium, and mercury resistance genes in 65% (<i>n</i> = 71) of the ST5-SCC<i>mec</i>I isolates. We also observed a geographic divergence associated with the presence of pSCL4752 in Chilean isolates, with a higher frequency in isolates from Concepción (88%) compared to Santiago (29%). Interestingly, a molecular clock analysis revealed that this divergence occurred in the aftermath of an 8.8 Mw earthquake and tsunami that struck the Concepción area in 2010. Moreover, our results demonstrate that the carriage of pSCL4752 can be beneficial or detrimental for ST5-SCC<i>mec</i>I isolates, depending on the environmental availability of these heavy metals. Our results suggest that the divergence of the ST5-SCC<i>mec</i>I MRSA lineage in Latin America could have been fostered by environmental disasters and influenced by the presence/absence of HMRGs harbored in a plasmid.IMPORTANCEMethicillin-resistant <i>Staphylococcus aureus</i> (MRSA) is a major cause of life-threatening infections worldwide and a growing public health concern. The rise of antibiotic-resistant bacteria, such as MRSA, is often linked to genetic adaptations that enhance their survival. Our research sheds light on how environmental changes, such as those triggered by a natural disaster, can influence the evolution and geographic spread of a highly resistant MRSA lineage in Latin America. We identified a plasmid carrying genes for resistance to arsenic, cadmium, and mercury, which was associated with the geographic divergence of the ST5-SCC<i>mec</i>I MRSA lineage, with striking differences in its prevalence between regions affected by a major earthquake and tsunami. By linking environmental events to pathogen evolution, our study highlights the role of ecological pressures in the spread of MRSA. These findings emphasize the need to integrate environmental monitoring into public health strategies to better understand the global challenge of antimicrobial resistance.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0366924"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143657622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plant salicylic acid signaling is inhibited by a cooperative strategy of two powdery mildew effectors.","authors":"Yuhan Liu, Xiao Li, Qiguang He, Minghao Zuo, Yinjie Guo, Lijuan Liu, Jinyao Yin, Lijuan He, Xiaoli Li, Jiaxin Shan, Wenbo Liu, Chunhua Lin, Weiguo Miao","doi":"10.1128/mbio.03959-24","DOIUrl":"10.1128/mbio.03959-24","url":null,"abstract":"<p><p>Powdery mildew is a global threat to crops and economically valuable plants. Salicylic acid (SA) signaling plays a significant role in plant resistance to biotrophic parasites; however, the mechanisms behind how powdery mildew fungi circumvent SA-mediated resistance remain unclear. Many phytopathogenic microbes deliver effectors into the host to sustain infection. In this study, we showed that the rubber tree powdery mildew fungus <i>Erysiphe quercicola</i> inhibits host SA biosynthesis by employing two effector proteins, EqCmu and EqPdt. These effector proteins can be delivered into plant cells to hydrolyze chorismate, the main precursor of SA, through their enzymatic activities. Notably, EqCmu and EqPdt can interact with each other, providing mutual protection against protein degradation mediated by the plant ubiquitin-proteasome system. This interaction enhances their activities in the hydrolysis of chorismate. Our study reveals a new pathogenic strategy by which two powdery mildew effector proteins cooperate to evade recognition by dampening the host immune system.</p><p><strong>Importance: </strong>Powdery mildew fungi may develop diverse strategies to disturb salicylic acid (SA) signaling in plants, which plays an important role in activating immunity, and little is known about these strategies. Our results suggest that the <i>Erysiphe quercicola</i> effector protein EqCmu can be translocated into host cells and inhibit host SA levels during the infection stage; however, it is targeted by the plant ubiquitin-proteasome system (UPS) and ubiquitinated, which induces EqCmu degradation. To evade the UPS, EqCmu interacts with EqPdt, another <i>E. quercicola</i> effector protein, to prevent that ubiquitination. EqPdt also inhibits host SA biosynthesis through its prephenate dehydratase activity. Taken together, these two powdery mildew effector proteins cause a synergistic effect in disturbing host SA signaling. Our study also suggests that enhancing SA signaling is required for boosting immunity against powdery mildew fungus.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0395924"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143649779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inter-protomer opening cooperativity of envelope trimers positively correlates with HIV-1 entry stoichiometry.","authors":"Revansiddha H Katte, Wang Xu, Yang Han, Xinyu Hong, Maolin Lu","doi":"10.1128/mbio.02754-24","DOIUrl":"10.1128/mbio.02754-24","url":null,"abstract":"<p><p>HIV-1 entry to host cells is fulfilled by fusion, mediated by surface glycoprotein envelope (Env) trimers upon interaction with host receptors. The entry stoichiometry (T) defining the number of Env trimers required for fusion remains elusive. Stoichiometry was previously estimated using mathematical modeling of infectivity curves of pseudoviruses surface-decorated with heterotrimers containing wild-type and entry-deficient Env. Nevertheless, previous models rarely co-considered inter-protomer opening cooperativity (S, reflecting how CD4-induced conformational changes in one protomer affect the opening of adjacent protomers) and virion trimer number distributions, while experiments were limited to pseudoviruses. Here, we factored these two parameters into our models and included replication-competent virions. We provided simultaneous estimates of T and S under varying trimer number distributions and offered 2D stoichiometry maps for different Env strains. Our results depicted the interplay between viral infectivity and stoichiometry tuned by the number of trimers per virion. The estimates for all tested Env strains were prevalently higher (T ≥ 7 for BG505 or JR-FL, T ≥ 13 for NL4-3) than reported. A high degree of inter-protomer opening cooperativity was observed for the neutralization-sensitive NL4-3, while neutralization-resistant BG505 and JR-FL showed a low to intermediate degree. Entry stoichiometry and opening cooperativity were strikingly positive-correlated, implying tied inter-protomer and inter-Env cooperative interactions. Our findings provided an in-depth view of Env cooperativities during HIV-1 entry.IMPORTANCEThe sparsely distributed envelope (Env) trimers on the surface of HIV-1 work collaboratively to mediate viral entry into the host, the early step of infection. The number of interacting trimers with host receptors required for entry awaits elucidation. Here, we explored the cooperative interplay among and within Env trimers, shedding light on a previously overlooked dimension of HIV-1 entry. For the first time, we presented distributions of estimated parameters depicting the number of Env trimers and degrees of inter-protomer opening cooperativities using biologically relevant mathematic models combined with virion infectivity measurements. Our results demonstrated that the quantity of required functional trimers positively correlates with inter-protomer opening cooperativity, a feature conserved across various strains. Our findings underscore cooperative behavior as an inherent characteristic of Env dynamics during HIV-1 entry. These insights enhance our understanding of HIV-1 infection mechanisms and could inform strategies for developing effective inhibitors or neutralizing agents.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0275424"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143492664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SENP1-SIRT3 axis mediates glycolytic reprogramming to suppress inflammation during <i>Listeria monocytogenes</i> infection.","authors":"Yan Xiong, Yongliang Du, Feng Lin, Beibei Fu, Dong Guo, Zhou Sha, Rong Tian, Rui Yao, Lulu Wang, Zixuan Cong, Bohao Li, Xiaoyuan Lin, Haibo Wu","doi":"10.1128/mbio.02524-24","DOIUrl":"10.1128/mbio.02524-24","url":null,"abstract":"<p><p><i>Listeria monocytogenes,</i> a foodborne pathogen, has the ability to invade intestinal mucosal cells, undergo intracellular proliferation, activate host immune responses, and induce diseases such as colitis. We have demonstrated that sentrin-specific protease 1 (SENP1) functions as a protective gene in the host, suppressing the inflammatory response triggered by <i>Listeria monocytogenes</i>. The host's SENP1-SIRT3 axis plays a critical role in regulating inflammation during <i>Listeria monocytogenes</i> infection. Our findings reveal that overexpression of SENP1, particularly under <i>Listeria monocytogenes</i> infection conditions (MOI = 20), effectively suppresses inflammation through modulation of glycolysis. Mechanistically, during <i>Listeria monocytogenes</i> infection, SENP1 accumulates in the mitochondria, facilitating the de-SUMOylation and activation of sirtuin 3 (SIRT3). Activated SIRT3 then regulates the deacetylation of pyruvate kinase M2 (PKM2), leading to a decrease in glycolytic intermediates, downregulation of glycolysis-related gene expression, and suppression of inflammation. Taken together, our study provides a deeper understanding of the mechanistic role of the SENP1-SIRT3 axis in the regulation of inflammation, offering novel insights, and strategies for the treatment and prevention of inflammatory diseases.</p><p><strong>Importance: </strong>Sentrin-specific protease 1 (SENP1)-sirtuin 3 (SIRT3) has never been reported in the regulation of bacteria-induced inflammation. Our study demonstrated that SENP1 acted as a protective factor against <i>Listeria</i>-induced inflammation by promoting SIRT3 activation and subsequent metabolic reprogramming. The SENP1-SIRT3 axis served not only as an essential signaling pathway for regulating mitochondrial metabolic responses to metabolic stress but also responds to bacterial invasion and plays a protective role in the organism. Our findings provide a basis for further research into targeting the SENP1-SIRT3 signaling pathway for the treatment of bacterial infections.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0252424"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lost in translation: conserved amino acid usage despite extreme codon bias in foraminifera.","authors":"Auden E Cote-L'Heureux, Elinor G Sterner, Xyrus X Maurer-Alcalá, Laura A Katz","doi":"10.1128/mbio.03916-24","DOIUrl":"10.1128/mbio.03916-24","url":null,"abstract":"<p><p>Analyses of codon usage in eukaryotes suggest that amino acid usage responds to GC pressure so AT-biased substitutions drive higher usage of amino acids with AT-ending codons. Here, we combine single-cell transcriptomics and phylogenomics to explore codon usage patterns in foraminifera, a diverse and ancient clade of predominantly uncultivable microeukaryotes. We curate data from 1,044 gene families in 49 individuals representing 28 genera, generating perhaps the largest existing dataset of data from a predominantly uncultivable clade of protists, to analyze compositional bias and codon usage. We find extreme variation in composition, with a median GC content at fourfold degenerate silent sites below 3% in some species and above 75% in others. The most AT-biased species are distributed among diverse non-monophyletic lineages. Surprisingly, despite the extreme variation in compositional bias, amino acid usage is highly conserved across all foraminifera. By analyzing nucleotide, codon, and amino acid composition within this diverse clade of amoeboid eukaryotes, we expand our knowledge of patterns of genome evolution across the eukaryotic tree of life.IMPORTANCEPatterns of molecular evolution in protein-coding genes reflect trade-offs between substitution biases and selection on both codon and amino acid usage. Most analyses of these factors in microbial eukaryotes focus on model species such as <i>Acanthamoeba, Plasmodium,</i> and yeast, where substitution bias is a primary contributor to patterns of amino acid usage. Foraminifera, an ancient clade of single-celled eukaryotes, present a conundrum, as we find highly conserved amino acid usage underlain by divergent nucleotide composition, including extreme AT-bias at silent sites among multiple non-sister lineages. We speculate that these paradoxical patterns are enabled by the dynamic genome structure of foraminifera, whose life cycles can include genome endoreplication and chromatin extrusion.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0391624"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143557317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low-dose interleukin 2 therapy halts the progression of post-streptococcal autoimmune complications in a rat model of rheumatic heart disease.","authors":"Rukshan Ahamed Mohamed Rafeek, Natkunam Ketheesan, Michael F Good, Manisha Pandey, Ailin Lepletier","doi":"10.1128/mbio.03823-24","DOIUrl":"10.1128/mbio.03823-24","url":null,"abstract":"<p><p>Acute rheumatic fever (ARF) is an autoimmune disease triggered by antibodies and T cells targeting the group A <i>Streptococcus</i> (GAS, Strep A) bacterium, often leading to rheumatic heart disease (RHD) and Sydenham's chorea. Long-term monthly penicillin injections are recognized as a cornerstone of public health programs to prevent Strep A reinfection and progression of ARF. However, compliance is poor, and better tools are required to slow disease progression. Preclinical evidence suggests that this can be achieved. Using a rat model that replicates post-streptococcal autoimmune complications, we explored the potential of low-dose interleukin-2 (LD-IL-2) as an immunotherapeutic intervention for ARF/RHD. In this model, injections of recombinant M protein from Strep A type 5 (rM5) to Lewis rats induce cardiac tissue inflammation, conduction abnormalities, and cross-reactive antibodies against cardiac and brain proteins central to disease pathogenesis. In animals injected with rM5 and treated with LD-IL-2, no cardiac functional or histological changes was observed. LD-IL-2 therapy effectively reduced the production of cross-reactive antibodies raised against host proteins and significantly increased regulatory T cells in the mediastinal lymph nodes. These novel findings suggest that LD-IL-2 will be an effective immunotherapeutic agent for treating ARF and has the potential to replace the standard monthly penicillin injections.</p><p><strong>Importance: </strong>Post-streptococcal autoimmune syndromes, including acute rheumatic fever, rheumatic heart disease, and Sydenham's chorea, represent a significant yet often under-recognized health and economic burden. This is especially true in low-income countries and among Indigenous populations in high-income nations, where the disease burden is most severe. These conditions arise from an autoimmune response to group A <i>Streptococcus</i> infections, leading to long-term health complications, disability, and premature death. Despite their widespread impact, no vaccine is currently available to prevent reinfections, and no specific therapy exists to treat the resulting autoimmune process. This study uses a rat model of rheumatic heart disease to evaluate the potential of low-dose interleukin 2 therapy in improving clinical outcomes and reducing the incidence of autoimmune diseases triggered by streptococcal infections.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0382324"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143492668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"EV68-228-N monoclonal antibody treatment halts progression of paralysis in a mouse model of EV-D68 induced acute flaccid myelitis.","authors":"Michael J Rudy, Courtney J Wilson, Brendan Hinckley, Danielle C Baker, Joshua M Royal, Marshall P Hoke, Miles B Brennan, Matthew R Vogt, Penny Clarke, Kenneth L Tyler","doi":"10.1128/mbio.03906-24","DOIUrl":"10.1128/mbio.03906-24","url":null,"abstract":"<p><p>In 2014, 2016, and 2018, infection with enterovirus D68 (EV-D68) was associated with outbreaks of a poliomyelitis-like paralytic syndrome, called acute flaccid myelitis (AFM). While only a small fraction of patients infected with EV-D68 developed AFM, this subgroup of patients does not typically seek treatment until after the onset of neurological symptoms. There are currently no approved human monoclonal antibody therapies or vaccines available for EV-D68. Here, we show that a monoclonal antibody, EV68-228-N, can quickly stop the progression of paralysis in a mouse model of AFM, even when treatment is initiated after the onset of paralysis. We found that EV68-228-N effectively halted the progression of paralysis when tested against both 2014 and 2016 EV-D68 isolates in an immunocompetent mouse model of AFM. All animal experiments were conducted in a blinded fashion. The IC₅₀ of EV68-228-N against 2014 and 2016 EV-D68 isolates was confirmed <i>in vitro</i> to be less than 330 ng/mL, and EV68-228-N was found to be equally effective at neutralizing 2018 and 2022 viral isolates without any evidence of emerging resistance. We further show that, following infection with EV-D68, mice treated with EV68-228-N have more surviving motor neurons in the spinal cord's lumbar enlargement than control treated animals. Taken together, this work suggests that EV68-228-N treatment has the potential to halt the progression of paralysis in AFM patients who present at the clinic with neurologic symptoms and that EV68-228-N will retain neutralization potential against emerging EV-D68 isolates.</p><p><strong>Importance: </strong>Enterovirus D-68 (EV-D68) associated acute flaccid myelitis (AFM) is an emergent poliomyelitis-like illness occurring predominantly in children. There are currently no proven effective therapies. We describe the use of a human monoclonal antibody (EV68-228-N) in a murine model of EV-D68 AFM in which therapy prevents progression of paralysis even when treatment is instituted after onset of weakness.</p><p><strong>Clinical trials: </strong>This study is registered with ClinicalTrials.gov as NCT06444048.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0390624"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143692699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"E3 ubiquitin ligase MARCH5 positively regulates Japanese encephalitis virus infection by catalyzing the K27-linked polyubiquitination of viral E protein and inhibiting MAVS-mediated type I interferon production.","authors":"Chenxi Li, Chenyang Tang, Xiqian Liu, Ying Liu, Linjie Zhang, Jing Shi, Qingyu Li, Mingan Sun, Yanhua Li","doi":"10.1128/mbio.00208-25","DOIUrl":"10.1128/mbio.00208-25","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Membrane-associated RING-CH-type finger (MARCH) proteins, a class of E3 ubiquitin ligases, have been reported to be involved in the infection of multiple viruses and the regulation of type I interferon (IFN) production. However, the specific role and mechanisms by which MARCH proteins influence Japanese encephalitis virus (JEV) infection remain poorly understood. Here, we systematically investigate the functional relevance of MARCH proteins in JEV replication by examining the effects of siRNA-mediated knockdown of MARCHs on viral infection. We identified MARCH5 as a positive regulator of JEV replication. The knockout of MARCH5 dramatically reduced viral yields, whereas its overexpression significantly enhanced JEV replication. Mechanistically, MARCH5 specifically interacts with the JEV envelope (E) protein and promotes its K27-linked polyubiquitination at the lysine (K) residues 136 and 166. This ubiquitination enhances viral attachment to permissive cells. Substituting these lysine residues with arginine (R) attenuated JEV replication &lt;i&gt;in vitro&lt;/i&gt; and reduced viral virulence &lt;i&gt;in vivo&lt;/i&gt;. Furthermore, JEV infection upregulated the expression of MARCH5. We also discovered that MARCH5 degrades mitochondrial antiviral-signaling protein (MAVS) through the ubiquitin-proteasome pathway by catalyzing its K48-linked ubiquitination, thereby inhibiting type I IFN production in JEV-infected cells. This suppression of type I IFN further facilitates JEV infection. In conclusion, these findings disclosed a novel role of MARCH5 in positively regulating JEV infection and revealed an important mechanism employed by MARCH5 to regulate the innate immune response.IMPORTANCEJEV is the leading cause of viral encephalitis in many countries of Asia with an estimated 100,000 clinical human cases and causes economic loss to the swine industry. Until now, there is no clinically approved antiviral for the treatment of JEV infection. Although vaccination prophylaxis is widely regarded as the most effective strategy for preventing Japanese encephalitis (JE), the incidence of JE cases continues to rise. Thus, a deeper understanding of virus-host interaction will enrich our knowledge of the mechanisms underlying JEV infection and identify novel targets for the development of next-generation live-attenuated vaccines and antiviral therapies. To the best of our knowledge, this study is the first to identify MARCH5 as a pro-viral host factor that facilitates JEV infection. We elucidated two distinct mechanisms by which MARCH5 promotes JEV infection. First, MARCH5 interacts with viral E protein and mediates the K27-linked ubiquitination of E protein at the K136 and K166 residues to facilitate efficient viral attachment. Furthermore, double mutations of K136R-K166R attenuated JEV infection &lt;i&gt;in vitro&lt;/i&gt; and reduced viral virulence in mice. Second, the upregulated expression of MARCH5 induced by JEV infection further suppresses the RIG-I-like receptor (RLR) signaling pat","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0020825"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intravacuolar persistence in neutrophils facilitates <i>Listeria monocytogenes</i> spread to co-cultured cells.","authors":"Stefano Bagatella, Camille Monney, Natascha Gross, Véronique Bernier Gosselin, Gertraud Schüpbach-Regula, Andrew Hemphill, Anna Oevermann","doi":"10.1128/mbio.02700-24","DOIUrl":"10.1128/mbio.02700-24","url":null,"abstract":"<p><p>The bacterium <i>Listeria monocytogenes</i> (<i>Lm</i>) causes listeriosis in humans and ruminants. Acute lesions are predominantly infiltrated by polymorphonuclear neutrophils (PMNs), considered to be the efficient bactericidal arm of innate immunity. However, recent evidence suggests that PMNs cannot achieve antilisterial sterilizing immunity and that <i>Lm</i> may persist within PMNs. Despite this, interactions between PMNs and <i>Lm</i> remain poorly understood. In this study, we characterized the listericidal activity and interaction dynamics of bovine PMNs with <i>Lm ex vivo</i>. Phagocytosed <i>Lm</i> failed to escape into the PMN cytosol and was primarily targeted by phagolysosomal mechanisms. However, PMNs enabled prolonged intravacuolar survival of a resilient <i>Lm</i> subpopulation, largely as viable but non-culturable (VBNC) bacteria. This resilient <i>Lm</i> population could spread from PMNs to a cell line, resuscitate, and complete its canonical life cycle, thereby perpetuating the infection. Therefore, we identify PMNs as a mobile niche for <i>Lm</i> survival and provide evidence that PMNs harbor VBNC bacteria, potentially facilitating <i>Lm</i> dissemination within the host.</p><p><strong>Importance: </strong><i>Listeria monocytogenes</i> (<i>Lm</i>) is a significant foodborne pathogen responsible for high hospitalization rates in humans, especially vulnerable groups such as the elderly, pregnant women, and immunocompromised individuals. In animals like ruminants, <i>Lm</i> infection leads to severe disease manifestations, notably brainstem encephalitis. This study uncovers a novel mechanism by which bovine neutrophils (PMNs) harbor <i>Lm</i> in a viable but non-culturable (VBNC) state, enabling the bacteria to hide in the host. PMNs, traditionally viewed as bacteria killers, may serve as Trojan horses, allowing <i>Lm</i> to persist and spread within the host. This discovery has broad implications for understanding <i>Lm</i>'s persistence, its role in recurrent infections, and the development of new therapeutic strategies targeting VBNC forms of <i>Lm</i> to improve treatment outcomes and disease control.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0270024"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}