mBio最新文献

{"title":"Novel small non-coding RNAs of Epstein-Barr virus upregulated upon lytic reactivation aid in viral genomic replication and virion production.","authors":"Sagarika Banerjee, Dipayan Bose, Steve Johnson, Jie Liu, Herbert Virgin, Erle S Robertson","doi":"10.1128/mbio.04060-24","DOIUrl":"10.1128/mbio.04060-24","url":null,"abstract":"<p><p>Epstein-Barr virus (EBV) employs various strategies for long-term survival, including the expression of non-coding RNAs (ncRNAs). This study uncovers and characterizes two novel EBV-encoded ncRNAs, p7 and p8, which are upregulated during lytic reactivation and interact with both viral and host genomes. These ncRNAs bind to cellular RNA transcripts, significantly reducing ARMCX3 mRNA levels, while p8 also influences PTPN6 and RPL24 expressions. Although p7 does not directly bind to LMP1 RNA but both ncRNAs found to downregulate LMP1 expression. Furthermore, these ncRNAs interact with the OriLyt region of EBV genome, promoting viral DNA replication. Functional assays indicate that p7 and p8 enhance cell proliferation and inhibit apoptosis by modulating the p53 pathway and suppressing pro-apoptotic proteins. These findings highlight the role of p7 and p8 in supporting EBV persistence by regulating viral replication, cell survival, and immune evasion, making them promising targets for therapeutic strategies in EBV-related diseases.IMPORTANCEEpstein-Barr virus (EBV) employs diverse strategies for long-term persistence in the host, including the expression of viral non-coding RNAs (ncRNAs) that manipulate key cellular pathways to promote viral replication and immune evasion. This study identifies two novel EBV-encoded ncRNAs, p7 and p8, which are upregulated during lytic reactivation and interact with both viral and host genes to regulate viral DNA replication and promote host cellular survival. By modulating apoptotic and proliferative pathways, p7 and p8 facilitate viral reactivation while promoting host cell survival, highlighting their potential as critical regulators in EBV-driven oncogenesis. This discovery expands our understanding of EBV-host interactions, suggesting p7 and p8 as targets for novel therapeutic strategies in EBV-associated malignancies.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0406024"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077129/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143803515","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 novel micronemal protein MP38 is involved in the invasion of merozoites into erythrocytes.","authors":"Tuyet-Kha Nguyen, Sy-Thau Nguyen, Van-Truong Nguyen, Sung-Hun Na, Robert W Moon, Jetsumon Sattabongkot, Yee Ling Lau, Won-Sun Park, Wan-Joo Chun, Feng Lu, Seong-Kyun Lee, Jin-Hee Han, Eun-Taek Han","doi":"10.1128/mbio.03917-24","DOIUrl":"10.1128/mbio.03917-24","url":null,"abstract":"<p><p>The absence of an <i>in vitro</i> cultivation system for <i>Plasmodium vivax</i> hinders the exploration of molecular targets for vaccine development. To address this, functional studies often rely on alternative models, such as <i>P. knowlesi</i>, due to its genetic similarity to <i>P. vivax</i>. This study investigated the role of a novel micronemal protein, PvMP38 (PVX_110945), in both <i>P. vivax</i> and <i>P. knowlesi</i> merozoite invasion of erythrocytes. The full-length ectodomain of PvMP38 was expressed, and polyclonal antibodies were generated to assess its function. PvMP38 was confirmed to localize on micronemal organelle in both <i>P. vivax</i> and <i>P. knowlesi</i> merozoites. <i>In vitro</i> protein-protein interaction assays revealed that PvMP38 binds to Pv12 with high-affinity interaction. A conserved novel complex of Pv12-Pv41-PvMP38 was identified by immunoprecipitation of <i>P. vivax</i> antibodies on <i>P. knowlesi</i> schizont lysates. Linear epitopes of PvMP38 with high and moderate antigenicity were identified in clinical isolates of both species. Invasion inhibition assays demonstrated that a triple antibody combination targeting the PvMP38, Pv12, and Pv41 significantly reduced <i>P. knowlesi</i> merozoite invasion of erythrocytes compared to a single antibody. In addition, CRISPR/Cas9-mediated knockout of <i>P. knowlesi mp38</i> markedly impaired parasite growth, underscoring its essential role during the asexual stage. These findings identify PvMP38 and its associated complex as promising targets for malaria interventions and highlight the utility of <i>P. knowlesi</i> as a model for investigating <i>P. vivax</i> erythrocyte invasion mechanisms.IMPORTANCEThis manuscript reported an effort in malaria eradication by identifying and functionally characterizing a novel <i>Plasmodium vivax</i> micronemal protein, PvMP38, involved in erythrocyte invasion. A narrow repertoire of an efficacious vaccine targeting <i>P. vivax</i> candidates is being developed due to the lack of continuous <i>in vitro</i> culture. This study addresses a gap in <i>P. vivax</i> research using <i>P. knowlesi</i> as a model for both genome editing and antibody functionality validation. By enhancing the protein-protein interaction screening framework, this study demonstrated that PvMP38 forms a complex with Pv12 and Pv41, opening the approaches to multi-antigen vaccines. The successful application of CRISPR/Cas9 gene editing techniques to disrupt its homolog, the <i>pkmp38</i> gene, further assesses the protein's significance in the growth and invasion of the parasite. These findings provided valuable insights into the biology of <i>P. vivax</i> and proposed PvMP38 as a promising candidate for malaria intervention strategies.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0391724"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077092/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143811746","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":"Impact of HIV-1 capsid polymorphisms on viral infectivity and susceptibility to lenacapavir.","authors":"Derek Hansen, Matthew R Hendricks, Silvia Chang, Arthur Cai, Jason K Perry, Thomas Aeschbacher, Ross Martin, Tomas Cihlar, Stephen R Yant","doi":"10.1128/mbio.00187-25","DOIUrl":"10.1128/mbio.00187-25","url":null,"abstract":"<p><p>Lenacapavir (LEN) is a first-in-class capsid (CA) inhibitor for the treatment and prevention of HIV-1 infection. While LEN has shown potent antiviral activity across all major HIV-1 subtypes, the impact of existing HIV-1 CA sequence diversity on the activity of LEN remains to be determined. Here, we identified natural polymorphisms within the LEN-binding site and assessed each for their impact on viral infectivity and susceptibility to LEN. Using a co-crystal structure of LEN in complex with a CA hexamer, we identified 29 binding site residues within five angstroms of LEN and analyzed each for naturally occurring polymorphisms across a multiclade collection of >10,000 unique HIV-1 <i>gag</i> sequences. Eleven of these CA residues, including five (M66, Q67, K70, N74, and A105) previously associated with LEN resistance when mutated, were invariant across these sequences. The remaining 18 residues showed one or more substitutions with a ≥0.5% prevalence for a total of 54 CA polymorphisms. When introduced as site-directed mutants (SDMs) in an NL4.3-based reporter virus and evaluated for infectivity and drug susceptibility in MT-4 cells, 74% (40/54) showed impaired infectivity (0.01%-77% of wild type), with 96% (46/48) exhibiting minimal change (less than threefold) in susceptibility to LEN. While CA substitutions L56V and N57H conferred high-level resistance to LEN (72- and 4,890-fold, respectively), both variants showed diminished replication capacity in primary T-cells relative to the wild-type virus. Collectively, these results indicate that existing CA natural HIV-1 sequence diversity within the LEN-binding site is rare and should minimally impact LEN efficacy in treatment-naïve individuals.IMPORTANCEHIV-1 capsid protein mediates multiple essential functions throughout the viral replication cycle, making it an attractive target for therapeutic intervention. Lenacapavir (LEN), a first-in-class HIV-1 capsid inhibitor, is being evaluated as a long-acting option in multiple ongoing clinical studies for HIV treatment and prevention. Twice-yearly lenacapavir is approved in multiple countries for the treatment of adults with multi-drug-resistant HIV-1 in combination with other antiretrovirals, and its investigational use for pre-exposure prophylaxis has shown 99.9%-100% efficacy in preventing HIV infection among a broad and geographically diverse range of study participants. In this report, we investigated how HIV-1 sequence diversity within the LEN binding site may impact virus replication capacity and sensitivity to LEN. Our data demonstrate high capsid sequence conservation across a large and diverse collection of HIV-1 variants, with the majority of naturally occurring capsid polymorphisms having a detrimental effect on viral infectivity and minimal impact on susceptibility to LEN.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":"16 5","pages":"e0018725"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077089/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143970428","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":"<i>Shigella</i> humoral immunity during the first 2 years of life in children from endemic areas.","authors":"Esther Ndungo, Ushasi Bhaumik, Yuanyuan Liang, Wilbur H Chen, Mark A Travassos, Milagritos D Tapia, Karen L Kotloff, Myron M Levine, Marcela F Pasetti","doi":"10.1128/mbio.00555-25","DOIUrl":"10.1128/mbio.00555-25","url":null,"abstract":"<p><p><i>Shigella</i> is a leading cause of moderate-to-severe diarrhea, primarily affecting children in impoverished regions. Disease incidence is highest in toddlers 1-2 years of age. Acquisition of immunity over time reduces the risk of infection. However, the evolution of childhood immunity resulting from <i>Shigella</i> exposure and the host responses that mediate protection remain poorly understood. Gaining insight into the immunological features that develop over time and prevent subsequent <i>Shigella</i> infection is critical for guiding vaccine design. We examined the antigenic repertoire and magnitude of humoral immunity to <i>Shigella</i> in children < 2 years of age from three endemic areas-Bamako, Mali, and two sites (Afar and Tigray) in Ethiopia-using a qualified multiplex assay. Serum IgG and IgA specific to <i>Shigella</i> proteins (IpaB, IpaC, IpaD, IpaH, and VirG) and lipopolysaccharide (LPS) from <i>S. flexneri</i> 2a, <i>S. flexneri</i> 3a, <i>S. flexneri</i> 6, and <i>S. sonnei</i> were measured in three stratified age groups: 6-8, 12-17, and 18-24 months. The youngest group (6- to 8-month-olds) exhibited similar antibody profiles across all sites. By contrast, antibody levels in the 12- to 17- and 18- to 24-month-old age groups varied by both age and site, reflecting geographical differences in <i>Shigella</i> endemicity and exposure. Notably, most children in the 12- to 17-month-old age group had IgG levels below the adult protective thresholds identified in controlled human infection models, identifying a critical window of vulnerability that would require intervention. Our findings underscore the importance and value of <i>Shigella</i> serosurveillance in children from endemic regions to inform future vaccine rollout decisions.IMPORTANCE<i>Shigella</i> is a major cause of moderate-to-severe diarrhea, the most affected being young children from poor resource countries. <i>Shigella</i> species easily acquire antibiotic resistance, presenting a challenge to infection control. The development of vaccines for young children has been hindered by a lack of understanding of what constitutes protective immunity. Here, for the first time, we investigated the magnitude and specificity of <i>Shigella</i> humoral immunity evoked by natural exposure in children 6 months to 2 years old living in Mali and Ethiopia (<i>Shigella</i>-endemic areas) using a qualified multiplex assay. Antibody profiles varied with age and region, revealing epidemiological trends. Children 12-17 months old were identified as the most vulnerable to infection. Antibodies specific for conserved <i>Shigella</i> proteins were higher in older children, affirming their potential as vaccine candidates. <i>Shigella</i> serosurveillance is useful in guiding public health interventions.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":"16 5","pages":"e0055525"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077217/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144007104","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":"Characterization of a heme-degrading enzyme that mediates fitness and pathogenicity in <i>Enterococcus faecalis</i>.","authors":"Debra N Brunson, Haider Manzer, Alexander B Smith, Joseph P Zackular, Todd Kitten, José A Lemos","doi":"10.1128/mbio.00146-25","DOIUrl":"10.1128/mbio.00146-25","url":null,"abstract":"<p><p><i>Enterococcus faecalis</i>, a gut commensal, is a leading cause of opportunistic infections. Its virulence is linked to its ability to thrive in hostile environments, which includes host-imposed metal starvation. We recently showed that <i>E. faecalis</i> evades iron starvation using five dedicated transporters that collectively scavenge iron from host tissues. Interestingly, heme, the most abundant source of iron in the human body, supported the growth of a strain lacking all five iron transporters (Δ5Fe). To release iron from heme, many bacterial pathogens utilize heme oxygenase enzymes to degrade the porphyrin ring that coordinates the iron ion of heme. Although <i>E. faecalis</i> lacks these enzymes, bioinformatics revealed a potential ortholog of the anaerobic heme-degrading enzyme anaerobilin synthase, found in <i>Escherichia coli</i> and a few other gram-negative bacteria. Here, we demonstrated that deletion of OG1RF_RS05575 in <i>E. faecalis</i> (ΔRS05575) or in the Δ5Fe background (Δ5FeΔRS05575) led to intracellular heme accumulation and hypersensitivity under anaerobic conditions, suggesting <i>RS05575</i> encodes an anaerobilin synthase, the first of its kind described in gram-positive bacteria. Additionally, deletion of <i>RS05575</i>, either alone or in the Δ5Fe background, impaired <i>E. faecalis</i> colonization in the mouse gastrointestinal tract and virulence in mouse peritonitis and rabbit infective endocarditis models. These results support the proposal that RS05575 is responsible for the anaerobic degradation of heme and identifies this relatively new enzyme class as a novel factor in bacterial pathogenesis. The findings from this study are likely to have broad implications, as homologues of <i>RS05575</i> are found in other gram-positive facultative anaerobes.</p><p><strong>Importance: </strong>Heme is an important nutrient for bacterial pathogens, mainly for its ability to serve as an iron source during infection. While bacteria are known to release iron from heme using enzymes called heme oxygenases, a new family of anaerobic heme-degrading enzymes has been described recently in gram-negative bacteria. Here, we report the first description of anaerobic heme degradation by a gram-positive bacterium, the opportunistic pathogen <i>Enterococcus faecalis</i>, and link activity of this enzyme to their ability to colonize and infect the host. We also show that homologs of this enzyme are found in many gram-positive facultative anaerobes, implying that the ability to degrade heme under anaerobic conditions may be an overlooked fitness and virulence factor of bacterial pathogens.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":"16 5","pages":"e0014625"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077173/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144008386","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":"Public antibodies: convergent signatures in human humoral immunity against pathogens.","authors":"Vishal N Rao, Camila H Coelho","doi":"10.1128/mbio.02247-24","DOIUrl":"10.1128/mbio.02247-24","url":null,"abstract":"<p><p>The human humoral immune system has evolved to recognize a vast array of pathogenic threats. This ability is primarily driven by the immense diversity of antibodies generated by gene rearrangement during B cell development. However, different people often produce strikingly similar antibodies when exposed to the same antigen-known as public antibodies. Public antibodies not only reflect the immune system's ability to consistently select for optimal B cells but can also serve as signatures of the humoral responses triggered by infection and vaccination. In this Minireview, we examine and compare public antibody identification methods, including the identification criteria used based on V(D)J gene usage and similarity in the complementarity-determining region three sequences, and explore the molecular features of public antibodies elicited against common pathogens, including viruses, protozoa, and bacteria. Finally, we discuss the evolutionary significance and potential applications of public antibodies in informing the design of germline-targeting vaccines, predicting escape mutations in emerging viruses, and providing insights into the process of affinity maturation. The ongoing discovery of public antibodies in response to emerging pathogens holds the potential to improve pandemic preparedness, accelerate vaccine design efforts, and deepen our understanding of human B cell biology.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":"16 5","pages":"e0224724"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077206/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144024877","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":"<i>Aeromonas hydrophila</i> RTX adhesin has three ligand-binding domains that give the bacterium the potential to adhere to and aggregate a wide variety of cell types.","authors":"Qilu Ye, Robert Eves, Tyler D R Vance, Thomas Hansen, Adam P Sage, Andrea Petkovic, Brianna Bradley, Carlos Escobedo, Laurie A Graham, John S Allingham, Peter L Davies","doi":"10.1128/mbio.03158-24","DOIUrl":"10.1128/mbio.03158-24","url":null,"abstract":"<p><p>Bacteria often make initial contact with their hosts through the ligand-binding domains of large adhesin proteins. Recent analyses of repeats-in-toxin (RTX) adhesins in Gram-negative bacteria suggest that ligand-binding domains can be identified by the way they emerge from \"split\" domains within the adhesin. Here, using this criterion and an AlphaFold3 model of a 5047-residue RTX adhesin from <i>Aeromonas hydrophila,</i> we identified three different ligand-binding domains in this fibrillar protein. The crystal structures of the two novel domains were solved to 1.4 and 1.95 Å resolution, respectively, and demonstrate excellent agreement with their modeled structures. The other domain was recognized as a carbohydrate-binding module based on its beta-strand topology and confirmed by its micromolar affinity for fucosylated glycans, including the Lewis B and Y antigens. This lectin-like module, which was recombinantly produced with its companion split domain and nearby extender domain, bound to a wide variety of cells including yeasts, diatoms, erythrocytes, and human endothelial cells. In each case, 50 mM free fucose prevented this binding and may offer some protection from infection. The carbohydrate-binding module with its neighboring domains also caused aggregation of yeast and erythrocytes, which was again blocked by the addition of free fucose. The second putative ligand-binding domain has a beta-roll structure supported by a parallel alpha-helix, and the third is a homolog of a von Willebrand Factor A domain. These two domains bind to a more limited range of cell types, and their ligands have yet to be identified.IMPORTANCECharacterizing the ligand-binding domains of fibrillar adhesins is important for understanding how bacteria can colonize host surfaces and how this colonization might be blocked. Here, we show that the opportunistic pathogen, <i>Aeromonas hydrophila</i>, uses a carbohydrate-binding module (CBM) to attach to several different cell types. The CBM is one of three ligand-binding domains at the distal tip of the adhesin. Identifying the glycans bound by the CBM as Lewis B and Y antigens has helped explain the range of cell types that the bacterium will bind and colonize, and it has suggested sugars that might interfere with these processes. Indeed, fucose, which is a constituent of the Lewis B and Y antigens, is effective at 50 mM concentrations in blocking the attachment of the CBM to host cells. This will lead to the design of more effective inhibitors against bacterial infections.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":"16 5","pages":"e0315824"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077191/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144025049","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":"Evidence of a role for the F1 capsule of <i>Yersinia pestis</i> in enhancing transmission from mammals to fleas in a mouse model of bubonic plague.","authors":"Christopher F Bosio, Clayton O Jarrett, B Joseph Hinnebusch","doi":"10.1128/mbio.00301-25","DOIUrl":"10.1128/mbio.00301-25","url":null,"abstract":"<p><p>The F1 protein capsule of <i>Yersinia pestis</i> is encoded by the <i>caf</i> operon on the 100 kb plasmid pFra and is produced at high levels in the mammalian host. Although the F1 capsule is not an essential virulence factor in many mammals, <i>Y. pestis</i> isolates lacking the <i>caf</i> operon are very rare in nature, indicating an essential biological role. Here, we show that F1-negative Δ<i>caf</i> mutants of <i>Y. pestis</i> are virulent in a mouse model but with a longer time to terminal disease. Bacterial loads in the spleen at the terminal stage of plague were not significantly different from the wild type. However, the level of bacteremia reached by the Δ<i>caf</i> mutants was often significantly lower than the wild type. Fleas that fed on moribund mice infected with the Δ<i>caf</i> mutants ingested the expected number of bacteria, but most mice had levels of bacteremia too low to support the development of a transmissible infection in the flea. A complemented Δ<i>caf</i> mutant restored wildtype levels of bacteremia and median time to death. F1-negative <i>Y. pestis</i> have a more pronounced autoaggregative phenotype, both <i>in vitro</i> and <i>in vivo</i>, which likely leads to a higher degree of sequestration in the spleen and other tissues. Therefore, an important biological role of the F1 capsule may be to enable <i>Y. pestis</i> to achieve bacteremia levels high enough to efficiently infect fleas, thereby enhancing stable flea-borne transmission cycles of <i>Y. pestis</i>.IMPORTANCEArthropod-borne pathogens face two fundamental challenges in completing their life cycle-they must produce a transmissible infection in both their mammalian and arthropod hosts. In order to effectively infect its flea vector, <i>Yersinia pestis</i>, the bacterial agent of plague, must generate a high-density bacteremia in the mammalian hosts that the fleas feed upon. In this study, we found that the F1 protein capsule of <i>Y. pestis</i> enhances the production of high bacteremia at the terminal stage of plague in a mouse model, thereby promoting successful mammal-to-flea transmission. Acquisition of the plasmid that encodes the F1 capsule occurred early in the evolutionary divergence of <i>Y. pestis</i> from <i>Yersinia pseudotuberculosis</i> and was likely to have been a key step in the transition to a flea-borne lifestyle.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0030125"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077185/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143710597","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":"Common challenges faced by early-career researchers in Latin American and small U.S. universities.","authors":"Daniela Cejas, Fatima Rodriguez Acosta, Juan Rivera-Correa","doi":"10.1128/mbio.00238-25","DOIUrl":"https://doi.org/10.1128/mbio.00238-25","url":null,"abstract":"<p><p>Early-career researchers from Spanish-speaking Latin American countries and small U.S. universities are underrepresented in international scientific databases. They have geographical importance, infectious disease endemicity, and exceptional researchers in microbiology, but these factors do not translate to representation in high-impact scientific publications. Many reasons could be involved, including financial burdens such as the inability to pay article processing charges. Additional teaching, institutional, and service responsibilities also highly influence their research productivity. Despite this, they are expected to publish high-impact articles, and their career development highly depends on it. There is an opportunity for global peer collaboration to tackle this inequity and uplift underrepresented scientists, which will ultimately provide benefits and sustainability to the global microbial sciences.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0023825"},"PeriodicalIF":5.1,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144003456","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":"Nitrogen cycling during an Arctic bloom: from chemolithotrophy to nitrogen assimilation.","authors":"Rafael Laso-Pérez, Juan Rivas-Santisteban, Nuria Fernandez-Gonzalez, Christopher J Mundy, Javier Tamames, Carlos Pedrós-Alió","doi":"10.1128/mbio.00749-25","DOIUrl":"https://doi.org/10.1128/mbio.00749-25","url":null,"abstract":"<p><p>In the Arctic, phytoplankton blooms are recurring phenomena occurring during the spring-summer seasons and influenced by the strong polar seasonality. Bloom dynamics are affected by nutrient availability, especially nitrogen, which is the main limiting nutrient in the Arctic. This study aimed to investigate the changes in an Arctic microbial community using omics approaches during a phytoplankton bloom focusing on the nitrogen cycle. Using metagenomic and metatranscriptomic samples from the Dease Strait (Canada) from March to July (2014), we reconstructed 176 metagenome-assembled genomes. Bacteria dominated the microbial community, although archaea reached up to 25% of metagenomic abundance in early spring, when <i>Nitrososphaeria</i> archaea actively expressed genes associated with ammonia oxidation to nitrite (<i>amt, amo, nirK</i>). The resulting nitrite was presumably further oxidized to nitrate by a <i>Nitrospinota</i> bacterium that highly expressed a nitrite oxidoreductase gene (<i>nxr</i>). Since May, the constant increase in chlorophyll <i>a</i> indicated the occurrence of a phytoplankton bloom, promoting the successive proliferation of different groups of chemoorganotrophic bacteria (<i>Bacteroidota, Alphaproteobacteria, Gammaproteobacteria</i>). These bacteria showed different strategies to obtain nitrogen, whether it be from organic or inorganic sources, according to the expression patterns of genes encoding transporters for nitrogen compounds. In contrast, during summer, the chemolithotrophic organisms thriving during winter reduced their relative abundance and the expression of their catabolic genes. Based on our functional analysis, we see a transition from a community where nitrogen-based chemolitotrophy plays a relevant role to a chemoorganotrophic community based on the carbohydrates released during the phytoplankton bloom, where different groups seem to specialize in different nitrogen sources.IMPORTANCEThe Arctic is one of the environments most affected by anthropogenic climate change. It is expected that the rise in temperature and change in ice cover will impact the marine microbial communities and the associated biogeochemical cycles. In this regard, nitrogen is the main nutrient limiting Arctic phytoplankton blooms. In this study, we combine genetic and expression data to study the nitrogen cycle at the community level over a time series covering from March to July. Our results indicate the importance of different taxa (from archaea to bacteria) and processes (from chemolithoautotrophy to incorporation of different nitrogen sources) in the cycling of nitrogen during this period. This study provides a baseline for future research that should include additional methodologies like biogeochemical analysis to fully understand the changes occurring on these communities due to global change.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0074925"},"PeriodicalIF":5.1,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144031335","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}