mBio最新文献

{"title":"T lymphocyte-dependent IL-10 down-regulates a cytokine storm driven by <i>Toxoplasma gondii</i> GRA24.","authors":"Claire M Doherty, Paige R Patterson, Julie A Emeanuwa, Jessica Belmares Ortega, Barbara A Fox, David J Bzik, Eric Y Denkers","doi":"10.1128/mbio.01455-24","DOIUrl":"10.1128/mbio.01455-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;As a model organism in the study of immunity to infection, &lt;i&gt;Toxoplasma gondii&lt;/i&gt; has been instrumental in establishing key principles of host anti-microbial defense and its regulation. Here, we employed an attenuated uracil auxotroph strain of Type I &lt;i&gt;Toxoplasma&lt;/i&gt; designated OMP to further untangle the early immune response to this parasitic pathogen. Experiments using αβ T cell-deficient &lt;i&gt;Tcrb&lt;/i&gt;&lt;sup&gt;&lt;i&gt;-/-&lt;/i&gt;&lt;/sup&gt; mice unexpectedly revealed that an intact αβ T lymphocyte compartment was essential to survive infection with OMP. Subsequent antibody depletion and knockout mouse experiments demonstrated contributions from CD4&lt;sup&gt;+&lt;/sup&gt; T cells and most predominantly CD8&lt;sup&gt;+&lt;/sup&gt; T cells in resistance. Using transgenic knockout mice, we found only a partial requirement for IFN-γ and a lack of requirement for Toll-like receptor (TLR) adaptor MyD88 in resistance. In contrast to other studies on &lt;i&gt;Toxoplasma&lt;/i&gt;, the ability to survive OMP infection did not require IL-12p40. Surprisingly, T cell-dependent IL-10 was found to be critical for survival, and deficiency of this cytokine triggered an abnormally high systemic inflammatory response. We also found that parasite molecule GRA24, a dense granule protein that triggers TLR-independent IL-12 production, acts as a virulence factor contributing to death of OMP-infected &lt;i&gt;Tcrb&lt;/i&gt;&lt;sup&gt;&lt;i&gt;-/-&lt;/i&gt;&lt;/sup&gt; and &lt;i&gt;IL-10&lt;/i&gt;&lt;sup&gt;&lt;i&gt;-/-&lt;/i&gt;&lt;/sup&gt; mice. Furthermore, resistance against OMP was restored in &lt;i&gt;Tcrb&lt;/i&gt;&lt;sup&gt;&lt;i&gt;-/-&lt;/i&gt;&lt;/sup&gt; mice via monoclonal depletion of IL-12p40, suggesting that GRA24-induced IL-12 underlies the fatal immunopathology observed. Collectively, our studies provide insight into a novel and rapidly arising T lymphocyte-dependent anti-inflammatory response to &lt;i&gt;T. gondii&lt;/i&gt; which operates independently of MyD88 and IL-12 and that depends on the function of parasite-dense granule protein GRA24.IMPORTANCEAs a model infectious microbe and an important human pathogen, the apicomplexan &lt;i&gt;Toxoplasma gondii&lt;/i&gt; has provided many important insights into innate and adaptive immunity to infection. We show here that a low virulence uracil auxotrophic &lt;i&gt;Toxoplasma&lt;/i&gt; strain emerges as a virulent parasite in the absence of an intact T cell compartment. Both CD4&lt;sup&gt;+&lt;/sup&gt; and CD8&lt;sup&gt;+&lt;/sup&gt; T lymphocytes are required for optimal protection, in line with previous findings in other models of &lt;i&gt;Toxoplasma&lt;/i&gt; infection. Nevertheless, several novel aspects of the response were identified in our study. Protection occurs independently of IL-12 and MyD88 and only partially requires IFN-γ. This is noteworthy particularly because the cytokines IL-12 and IFN-γ have previously been regarded as essential for protective immunity to &lt;i&gt;T. gondii&lt;/i&gt;. Instead, we identified the anti-inflammatory effects of T cell-dependent IL-10 as the critical factor enabling host survival. The parasite dense granule protein GRA24, a host-directed mitogen-activated protein kinase activator, was ide","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0145524"},"PeriodicalIF":5.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11559025/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142503528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"HCV infection activates the proteasome via PA28γ acetylation and heptamerization to facilitate the degradation of RNF2, a catalytic component of polycomb repressive complex 1.","authors":"Hirotake Kasai, Atsuya Yamashita, Yasunori Akaike, Tomohisa Tanaka, Yoshiharu Matsuura, Kohji Moriishi","doi":"10.1128/mbio.01691-24","DOIUrl":"10.1128/mbio.01691-24","url":null,"abstract":"<p><p>We previously reported that hepatitis C virus (HCV) infection or HCV core protein expression induces HOX gene expression by impairing histone H2A monoubiquitination via a proteasome-dependent reduction in the level of RNF2, a key catalytic component of polycomb repressive complex 1 (H. Kasai, K. Mochizuki, T. Tanaka, A. Yamashita, et al., J Virol 95:e01784-20, 2021, https://doi.org/10.1128/jvi.01784-20). In this study, we aimed to investigate the mechanism by which HCV infection accelerates RNF2 degradation. Yeast two-hybrid screening and an immunoprecipitation assay revealed that RNF2 is a PA28γ-binding protein. The proteasome activator PA28γ destabilized the RNF2 protein in a proteasome-dependent manner, since RNF2 degradation was impaired by PA28γ knockout or MG132 treatment. HCV infection or core protein expression reduced the levels of RNF2 and histone H2A K119 monoubiquitination and induced the expression of HOX genes in the presence of PA28γ, while PA28γ knockout reversed these changes. Treatment with a lysine acetyltransferase inhibitor inhibited the acetylation of PA28γ at K195 and the degradation of the RNF2 protein, while treatment with a lysine deacetylase inhibitor accelerated these events in a PA28γ-dependent manner. RNF2 protein degradation was increased by expression of the acetylation mimetic PA28γ mutant but not by expression of the acetylation-defective mutant or the proteasome activation-defective mutant. Furthermore, HCV infection or core protein expression facilitated the interaction between PA28γ and the lysine acetyltransferase CBP/p300 and then accelerated PA28γ acetylation and heptazmerization to promote RNF2 degradation. These data suggest that HCV infection accelerates the acetylation-dependent heptamerization of PA28γ to increase the proteasomal targeting of RNF2.IMPORTANCEHCV is a causative agent of HCV-related liver diseases, including hepatic steatosis, cirrhosis, and hepatocellular carcinoma. PA28γ, which, in heptameric form, activates the 20S core proteasome for the degradation of PA28γ-binding proteins, is responsible for HCV-related liver diseases. HCV core protein expression or HCV infection accelerates RNF2 degradation, leading to the induction of HOX gene expression via a decrease in the level of H2Aub on HOX gene promoters. However, the mechanism of RNF2 degradation in HCV-infected cells has not been clarified. The data presented in this study suggest that PA28γ acetylation and heptamerization are promoted by HCV infection or by core protein expression to activate the proteasome for the degradation of RNF2 and are responsible for HCV propagation. This study provides novel insights valuable for the development of therapies targeting both HCV propagation and HCV-related diseases.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0169124"},"PeriodicalIF":5.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11559043/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142349636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A <i>Vibrio cholerae</i> anti-phage system depletes nicotinamide adenine dinucleotide to restrict virulent bacteriophages.","authors":"Yishak A Woldetsadik, David W Lazinski, Andrew Camilli","doi":"10.1128/mbio.02457-24","DOIUrl":"10.1128/mbio.02457-24","url":null,"abstract":"<p><p>Bacteria and their predatory viruses (bacteriophages or phages) are in a perpetual molecular arms race. This has led to the evolution of numerous phage defensive systems in bacteria that are still being discovered, as well as numerous ways of interference or circumvention on the part of phages. Here, we identify a unique molecular battle between the classical biotype of <i>Vibrio cholerae</i> and virulent phages ICP1, ICP2, and ICP3. We show that classical biotype strains resist almost all isolates of these phages due to a 25-kb genomic island harboring several putative anti-phage systems. We observed that one of these systems, Nezha, encoding SIR2<i>-</i>like and helicase proteins, inhibited the replication of all three phages. Bacterial SIR2-like enzymes degrade the essential metabolic coenzyme nicotinamide adenine dinucleotide (NAD⁺), thereby preventing replication of the invading phage. In support of this mechanism, we identified one phage isolate, ICP1_2001, which circumvents Nezha by encoding two putative NAD⁺ regeneration enzymes. By restoring the NAD⁺ pool, we hypothesize that this system antagonizes Nezha without directly interacting with its proteins and should be able to antagonize other anti-phage systems that deplete NAD⁺.IMPORTANCEBacteria and phages are in a perpetual molecular arms race, with bacteria evolving an extensive arsenal of anti-phage systems and phages evolving mechanisms to overcome these systems. This study identifies a previously uncharacterized facet of the arms race between <i>Vibrio cholerae</i> and its phages. We identify an NAD⁺-depleting anti-phage defensive system called Nezha, potent against three virulent phages. Remarkably, one phage encodes proteins that regenerate NAD⁺ to counter the effects of Nezha. Without Nezha, the NAD⁺ regeneration genes are detrimental to the phage. Our study provides new insight into the co-evolutionary dynamics between bacteria and phages and informs the microbial ecology and phage therapy fields.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0245724"},"PeriodicalIF":5.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11559045/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142391668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The conserved role of miR-2 and novel miR-109 in the increase in fecundity of <i>Diaphorina citri</i> induced by symbiotic bacteria and pathogenic fungi.","authors":"Xiaoge Nian, Shujie Wu, Jielan He, Paul Holford, George Andrew Charles Beattie, Desen Wang, Yijing Cen, Yurong He, Songdou Zhang","doi":"10.1128/mbio.01541-24","DOIUrl":"10.1128/mbio.01541-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Infection with pathogens can increase the fecundity and other fitness-related traits of insect vectors for their own advantage. Our previous research has reported the pivotal role of &lt;i&gt;DcKr-h1&lt;/i&gt; in the fecundity improvement of &lt;i&gt;Diaphorina citri&lt;/i&gt; induced by the bacterium, \"&lt;i&gt;Candidatus&lt;/i&gt; Liberibacter asiaticus\" (&lt;i&gt;C&lt;/i&gt;Las), and the fungus, &lt;i&gt;Cordyceps fumosorosea&lt;/i&gt; (&lt;i&gt;Cf&lt;/i&gt;). However, the posttranscriptional regulation of this process remains poorly understood. Given the significance of miRNAs in gene regulation, we delved into their roles in shaping phenotypes and their underlying molecular mechanisms. Our results indicated that two miRNAs, miR-2 and novel-miR-109, jointly inhibited &lt;i&gt;DcKr-h1&lt;/i&gt; expression by binding to its 3' untranslated region (UTR). In the &lt;i&gt;D. citri-C&lt;/i&gt;Las interaction, the expression levels of miR-2 and novel-miR-109 in the ovaries of &lt;i&gt;C&lt;/i&gt;Las-positive psyllids were lower compared to &lt;i&gt;C&lt;/i&gt;Las-negative individuals. Overexpression of miR-2 or novel-miR-109 significantly decreased fecundity and &lt;i&gt;C&lt;/i&gt;Las titer in ovaries and caused reproductive defects reminiscent of &lt;i&gt;DcKr-h1&lt;/i&gt; knockdown. Similarly, in the &lt;i&gt;D. citri-Cf&lt;/i&gt; interaction, the levels of miR-2 and novel-miR-109 markedly decreased in the ovaries. Upregulation of miR-2 or novel-miR-109 also resulted in reduced fecundity and ovary defects similar to those caused by &lt;i&gt;DcKr-h1&lt;/i&gt; silencing. Moreover, feeding antagomir-2 or antagomir-109 partially rescued the defective phenotypes caused by &lt;i&gt;DcKr-h1&lt;/i&gt; silencing in both model systems, and miR-2 and novel-miR-109 were repressed by juvenile hormone (JH) and regulated the genes associated with egg development. This study shows a conserved regulatory mechanism, whereby JH suppresses the expression of miR-2 and novel-miR-109 which, together with JH-induced transcription of &lt;i&gt;DcKr-h1&lt;/i&gt;, increases female fecundity induced by both symbiotic bacteria and pathogenic fungi.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Importance: &lt;/strong&gt;Infection with pathogens can increase the fecundity and other fitness-related traits of insect vectors for their own advantage. Our previous research has reported that &lt;i&gt;DcKr-h1&lt;/i&gt; plays a critical role in the increase in fecundity of &lt;i&gt;Diaphorina citri&lt;/i&gt; induced by the bacterium, \"Candidatus Liberibacter asiaticus\" (&lt;i&gt;C&lt;/i&gt;Las) and the fungus, &lt;i&gt;Cordyceps fumosorosea&lt;/i&gt; (&lt;i&gt;Cf&lt;/i&gt;). However, the posttranscriptional regulation of this process remains poorly understood. Given the significance of miRNAs in gene regulation, we delved into their roles in shaping phenotypes and their underlying molecular mechanisms. Our results indicated that two miRNAs, miR-2 and novel-miR-109, jointly inhibited &lt;i&gt;DcKr-h1&lt;/i&gt; expression by binding to its 3' untranslated region (UTR). In both &lt;i&gt;D. citri&lt;/i&gt;-&lt;i&gt;C&lt;/i&gt;Las and &lt;i&gt;D. citri&lt;/i&gt;-&lt;i&gt;Cf&lt;/i&gt; interactions, the increased juvenile hormone (JH) titer and reduced abundance of miR-2 and novel-miR-109 ensure high levels of &lt;i&gt;DcKr-h1&lt;/i&gt; exp","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0154124"},"PeriodicalIF":5.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11559015/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142381249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanisms of <i>Staphylococcus aureus</i> survival of trimethoprim-sulfamethoxazole-induced thymineless death.","authors":"Lauren J Gonsalves, Allyson Tran, Tessa Gardiner, Tiia Freeman, Angshita Dutta, Carson J Miller, Sharon McNamara, Adam Waalkes, Dustin R Long, Stephen J Salipante, Lucas R Hoffman, Daniel J Wolter","doi":"10.1128/mbio.01634-24","DOIUrl":"10.1128/mbio.01634-24","url":null,"abstract":"<p><p>Trimethoprim-sulfamethoxazole (SXT) is commonly used to treat diverse <i>Staphylococcus aureus</i> infections, including those associated with cystic fibrosis (CF) pulmonary disease. Studies with <i>Escherichia coli</i> found that SXT impairs tetrahydrofolate production, leading to DNA damage, stress response induction, and accumulation of reactive oxygen species (ROS) in a process known as thymineless death (TLD). TLD survival can occur through the uptake of exogenous thymidine, countering the effects of SXT; however, a growing body of research has implicated central metabolism as another potentially important determinant of bacterial survival of SXT and other antibiotics. Here, we conducted studies to better understand the mechanisms of TLD survival in <i>S. aureus</i>. We found that thymidine abundances in CF sputum were insufficient to prevent TLD of <i>S. aureus</i>, highlighting the importance of alternative survival mechanisms <i>in vivo</i>. In <i>S. aureus</i> cultured <i>in vitro</i> with SXT and low thymidine, we frequently identified adaptive mutations in genes encoding carbohydrate, nucleotide, and amino acid metabolism, supporting reduced metabolism as a common survival mechanism. Although intracellular ROS levels rose with SXT treatment <i>in vitro</i>, survival was not improved in the presence of ROS scavengers, unlike in <i>E. coli</i>. SXT challenge induced the SOS response, which was alleviated by added thymidine. Finally, an inactivating mutation in the phosphotransferase gene <i>ptsI</i> conferred both limitation in cellular ATP and improved survival against TLD. Collectively, these results suggest that alterations in core metabolic functions, particularly those that reduce ATP levels, predominantly confer <i>S. aureus</i> survival and persistence during SXT treatment, potentially identifying novel targets for co-treatment.IMPORTANCE<i>Staphylococcus aureus</i> is a ubiquitous organism and one of the leading causes of human infections, many of which are difficult to treat due to persistence, antibiotic resistance, or antibiotic tolerance. As our arsenal of effective antibiotics dwindles, the need for improved treatments becomes increasingly urgent, necessitating a better understanding of the precise mechanisms by which pathogens evade our most critical antimicrobial agents. Here, we report a systematic characterization of the mechanisms of <i>S. aureus</i> survival to treatment with the first-line antistaphylococcal antibiotic trimethoprim-sulfamethoxazole, identifying pathways and candidate targets for enhancing the efficacy of available antimicrobial agents.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0163424"},"PeriodicalIF":5.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11559000/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142503525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Avian influenza A (H5N1) virus in dairy cattle: origin, evolution, and cross-species transmission.","authors":"Ahmed Mostafa, Mahmoud M Naguib, Aitor Nogales, Ramya S Barre, James P Stewart, Adolfo García-Sastre, Luis Martinez-Sobrido","doi":"10.1128/mbio.02542-24","DOIUrl":"https://doi.org/10.1128/mbio.02542-24","url":null,"abstract":"<p><p>Since the emergence of highly pathogenic avian influenza virus (HPAIV) H5N1 of clade 2.3.4.4b as a novel reassortant virus from subtype H5N8, the virus has led to a massive number of outbreaks worldwide in wild and domestic birds. Compared to the parental HPAIV H5N8 clade 2.3.4.4b, the novel reassortant HPAIV H5N1 displayed an increased ability to escape species barriers and infect multiple mammalian species, including humans. The virus host range has been recently expanded to include ruminants, particularly dairy cattle in the United States, where cattle-to-cattle transmission was reported. As with the avian 2.3.4.4.b H5N1 viruses, the cattle-infecting virus was found to transmit from cattle to other contact animals including cats, raccoons, rodents, opossums, and poultry. Although replication of the virus in cows appears to be mainly confined to the mammary tissue, with high levels of viral loads detected in milk, infected cats and poultry showed severe respiratory disease, neurologic signs, and eventually died. Furthermore, several human infections with HPAIV H5N1 have also been reported in dairy farm workers and were attributed to exposures to infected dairy cattle. This is believed to represent the first mammalian-to-human transmission report of the HPAIV H5N1. Fortunately, infection in humans and cows, as opposed to other animals, appears to be mild in most cases. Nevertheless, the H5N1 bovine outbreak represents the largest outbreak of the H5N1 in a domestic mammal close to humans, increasing the risk that this already mammalian adapted H5N1 further adapts to human-to-human transmission and starts a pandemic. Herein, we discuss the epidemiology, evolution, pathogenesis, and potential impact of the recently identified HPAIV H5N1 clade 2.3.4.4b in dairy cattle in the United States. Eventually, interdisciplinary cooperation under a One Health framework is required to be able to control this ongoing HPAIV H5N1 outbreak to stop it before further expansion of its host range and geographical distribution.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0254224"},"PeriodicalIF":5.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142623718","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":"Frequent genetic exchanges revealed by a pan-mitogenome graph of a fungal plant pathogen.","authors":"Anouk C van Westerhoven, Jelmer Dijkstra, Jose L Aznar Palop, Kyran Wissink, Jasper Bell, Gert H J Kema, Michael F Seidl","doi":"10.1128/mbio.02758-24","DOIUrl":"https://doi.org/10.1128/mbio.02758-24","url":null,"abstract":"<p><p>Mitochondria are present in almost all eukaryotic lineages. The mitochondrial genomes (mitogenomes) evolve separately from nuclear genomes, and they can therefore provide relevant insights into the evolution of their host species. <i>Fusarium oxysporum</i> is a major fungal plant pathogen that is assumed to reproduce clonally. However, horizontal chromosome transfer between strains can occur through heterokaryon formation, and recently, signs of sexual recombination have been observed. Similarly, signs of recombination in <i>F. oxysporum</i> mitogenomes challenged the prevailing assumption of clonal reproduction in this species. Here, we construct, to our knowledge, the first fungal pan-mitogenome graph of nearly 500 <i>F</i>. <i>oxysporum</i> mitogenome assemblies to uncover the variation and evolution. In general, the gene order of fungal mitogenomes is not well conserved, yet the mitogenome of <i>F. oxysporum</i> and related species are highly colinear. We observed two strikingly contrasting regions in the <i>F. oxysporum</i> pan-mitogenome, comprising a highly conserved core mitogenome and a long variable region (6-16 kb in size), of which we identified three distinct types. The pan-mitogenome graph reveals that only five intron insertions occurred in the core mitogenome and that the long variable regions drive the difference between mitogenomes. Moreover, we observed that their evolution is neither concurrent with the core mitogenome nor with the nuclear genome. Our large-scale analysis of long variable regions uncovers frequent recombination between mitogenomes, even between strains that belong to different taxonomic clades. This challenges the common assumption of incompatibility between genetically diverse <i>F. oxysporum</i> strains and provides new insights into the evolution of this fungal species.IMPORTANCEInsights into plant pathogen evolution is essential for the understanding and management of disease. <i>Fusarium oxysporum</i> is a major fungal pathogen that can infect many economically important crops. Pathogenicity can be transferred between strains by the horizontal transfer of pathogenicity chromosomes. The fungus has been thought to evolve clonally, yet recent evidence suggests active sexual recombination between related isolates, which could at least partially explain the horizontal transfer of pathogenicity chromosomes. By constructing a pan-genome graph of nearly 500 mitochondrial genomes, we describe the genetic variation of mitochondria in unprecedented detail and demonstrate frequent mitochondrial recombination. Importantly, recombination can occur between genetically diverse isolates from distinct taxonomic clades and thus can shed light on genetic exchange between fungal strains.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0275824"},"PeriodicalIF":5.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142622430","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":"InSeq analysis of defined <i>Legionella pneumophila</i> libraries identifies a transporter-encoding gene cluster important for intracellular replication in mammalian hosts.","authors":"Caitlin E Moss, Craig R Roy","doi":"10.1128/mbio.01955-24","DOIUrl":"10.1128/mbio.01955-24","url":null,"abstract":"<p><p><i>Legionella pneumophila</i> is an intracellular bacterial pathogen that replicates inside human alveolar macrophages to cause a severe pneumonia known as Legionnaires' disease. <i>L. pneumophila</i> requires the Dot/Icm Type IV secretion system to deliver hundreds of bacterial proteins to the host cytosol that manipulate cellular processes to establish a protected compartment for bacterial replication known as the <i>Legionella-</i>containing vacuole. To better understand mechanisms apart from the Dot/Icm system that support survival and replication in this vacuole, we used transposon insertion sequencing in combination with defined mutant sublibraries to identify <i>L. pneumophila</i> fitness determinants in primary mouse macrophages and the mouse lung. This approach validated that many previously identified genes important for intracellular replication were critical for infection of a mammalian host. Further, the screens uncovered additional genes contributing to <i>L. pneumophila</i> replication in mammalian infection models. This included a cluster of seven genes in which insertion mutations resulted in <i>L. pneumophila</i> fitness defects in mammalian hosts. Generation of isogenic deletion mutants and genetic complementation studies verified the importance of genes within this locus for infection of mammalian cells. Genes in this cluster are predicted to encode nucleotide-modifying enzymes, a protein of unknown function, and an atypical ATP-binding cassette (ABC) transporter with significant homology to multidrug efflux pumps that has been named Lit<i>,</i> for <i>Legionella</i> infectivity transporter. Overall, these data provide a comprehensive overview of the bacterial processes that support <i>L. pneumophila</i> replication in a mammalian host and offer insight into the unique challenges posed by the intravacuolar environment.IMPORTANCEIntracellular bacteria employ diverse mechanisms to survive and replicate inside the inhospitable environment of host cells. <i>Legionella pneumophila</i> is an opportunistic human pathogen and a model system for studying intracellular host-pathogen interactions. Transposon sequencing is an invaluable tool for identifying bacterial genes contributing to infection, but current animal models for <i>L. pneumophila</i> are suboptimal for conventional screens using saturated mutant libraries. This study employed a series of defined transposon mutant libraries to identify determinants of <i>L. pneumophila</i> fitness in mammalian hosts, which include a newly identified bacterial transporter called Lit. Understanding the requirements for survival and replication inside host cells informs us about the environment bacteria encounter during infection and the mechanisms they employ to make this environment habitable. Such knowledge will be key to addressing future challenges in treating infections caused by intracellular bacteria.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0195524"},"PeriodicalIF":5.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11559062/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142372195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The feasibility of establishing a hamster model for HBV infection: <i>in vitro</i> evidence.","authors":"Hu Zhang, Yanan Liu, Cheng-Der Liu, Zhongde Wang, Haitao Guo","doi":"10.1128/mbio.02615-24","DOIUrl":"10.1128/mbio.02615-24","url":null,"abstract":"<p><p>Chronic hepatitis B virus (HBV) infection remains a significant public health burden with no cure currently available. The research to cure HBV has long been hampered by the lack of immunocompetent small animal models capable of supporting HBV infection. Here, we set out to explore the feasibility of the golden Syrian hamster as an immunocompetent small rodent model for HBV infection. We first started with <i>in vitro</i> assessments of the HBV replication cycle in primary hamster hepatocytes (PHaHs) by adenoviral HBV (Ad-HBV) transduction. Our results demonstrated that PHaHs support HBV reverse transcription and subsequent cccDNA formation via the intracellular recycling pathway. Next, with luciferase reporter assays, we confirmed that PHaHs support the activities of all HBV major promoters. Then, we transduced PHaHs with an adenoviral vector expressing HBV receptor human Na+/taurocholate cotransporting polypeptide NTCP (Ad-huNTCP), followed by HBV inoculation. While the untransduced PHaHs did not support HBV infection, Ad-huNTCP-transduced PHaHs supported <i>de novo</i> cccDNA formation, viral mRNA transcription, and expression of viral antigens. We then humanized the amino acid (aa) residues of hamster NTCP (haNTCP) critical for HBV entry, aa84-87 and aa157-165, and transfected HepG2 cells with constructs expressing wild-type haNTCP and humanized-haNTCP, H84R/P87N and H84R/P87N/G157K/M160V/M165L, respectively, followed by HBV inoculation. The results showed that the humanization of H84R/P87N alone was sufficient to support HBV infection at a level comparable to that supported by huNTCP. Taken together, the above <i>in vitro</i> evidence supports the future direction of humanizing haNTCP for HBV infection <i>in vivo</i>.IMPORTANCEOne of the biggest challenges in developing an HBV cure is the lack of immunocompetent animal models susceptible to HBV infection. Developing such models in mice has been unsuccessful due to the absence of a functional HBV receptor, human NTCP (huNTCP), and the defect in supporting viral cccDNA formation. In search of alternative models, we report herein multiple lines of <i>in vitro</i> evidence for developing a golden Syrian hamster model for HBV infection. We demonstrate that the primary hamster hepatocytes (PHaHs) support HBV replication, transcription, and cccDNA formation, and PHaHs are susceptible to <i>de novo</i> HBV infection in the presence of huNTCP. Furthermore, expressing hamster NTCP with two humanized residues critical for HBV entry renders HepG2 cells permissive to HBV infection. Thus, our work lays a solid foundation for establishing a gene-edited hamster model that expresses humanized NTCP for HBV infection <i>in vivo</i>.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0261524"},"PeriodicalIF":5.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11559161/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142349643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Epitranscriptomic m⁶A modifications during reactivation of HIV-1 latency in CD4⁺ T cells.","authors":"Tarun Mishra, Stacia Phillips, Yutao Zhao, Bethany Wilms, Chuan He, Li Wu","doi":"10.1128/mbio.02214-24","DOIUrl":"10.1128/mbio.02214-24","url":null,"abstract":"<p><p>Despite effective antiretroviral therapy reducing HIV-1 viral loads to undetectable levels, the presence of latently infected CD4⁺ T cells poses a major barrier to HIV-1 cure. <i>N</i>⁶-methyladenosine (m⁶A) modification of viral and cellular RNA has a functional role in regulating HIV-1 infection. m⁶A modification of HIV-1 RNA can affect its stability, translation, and splicing in cells and suppresses type-I interferon induction in macrophages. However, the function of m⁶A modification in regulating HIV-1 latency reactivation remains unknown. We used the Jurkat T cell line-derived HIV-1 latency model (J-Lat cells) to investigate changes in m⁶A levels of cellular RNA in response to latency reversal. We observed a significant increase in m⁶A levels of total cellular RNA upon reactivation of latent HIV-1 in J-Lat cells. This increase in m⁶A levels was transient and returned to steady-state levels despite continued high levels of viral gene expression in reactivated cells compared to control cells. Upregulation of m⁶A levels occurred without significant changes in the protein expression of m⁶A writers or erasers that add or remove m⁶A, respectively. Knockdown of m⁶A writers in J-Lat cells significantly reduced HIV-1 reactivation. Treatment with an m⁶A writer inhibitor reduced cellular RNA m⁶A levels, along with a reduction in HIV-1 reactivation. Furthermore, using m⁶A-specific sequencing, we identified cellular RNAs that are differentially m⁶A-modified during HIV-1 reactivation in J-Lat cells. Knockdown of identified m⁶A-modified RNA validates these results with an established primary CD4⁺ T cell model of HIV-1 latency. These results show the importance of m⁶A RNA modification in HIV-1 latency reversal.</p><p><strong>Importance: </strong>RNA m⁶A modification is important for regulating gene expression and innate immune responses to HIV-1 infection. However, the functional significance of m⁶A modification during HIV-1 latency reactivation is unknown. To address this important question, in this study, we used established cellular models of HIV-1 latency, m⁶A-specific sequencing at single-base resolution, and functional assays. We demonstrate that HIV-1 latency reversal leads to increased levels of cellular m⁶A modification, correlates with cellular m⁶A levels, and is dependent on the catalytic activity of the m⁶A methyltransferase enzyme. We also identified cellular genes that are differentially m⁶A-modified during HIV-1 reactivation, as well as the sites of m⁶A within HIV-1 RNA. Our novel findings point toward a significant role for m⁶A modification in HIV-1 latency reversal.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0221424"},"PeriodicalIF":5.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11559067/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142381248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}