Infection and Immunity最新文献

{"title":"<i>Candida albicans</i> biofilm extracellular vesicles deliver candidalysin to epithelial cell membranes and induce host cell responses.","authors":"Sejeong Lee, Antzela Tsavou, Robert Zarnowski, Rita Pforte, Stefanie Allert, Thomas Krüger, Olaf Kniemeyer, Axel A Brakhage, Tam T T Bui, David R Andes, Jonathan P Richardson, Bernhard Hube, Julian R Naglik","doi":"10.1128/iai.00404-24","DOIUrl":"10.1128/iai.00404-24","url":null,"abstract":"<p><p>Extracellular vesicles (EVs) are heterogeneous particles encapsulated with a phospholipid bilayer membrane. EVs have evolved diverse biological functions, serving mainly as prominent mediators and regulators of cell-cell communication. This study investigated whether candidalysin, a key virulence factor in <i>Candida albicans</i> infections, is present within EVs derived from <i>C. albicans</i> biofilms and retains activity by inducing host immune responses. We found that biofilm EVs contain candidalysin and can permeabilize planar lipid bilayer membranes in a dose-dependent manner. However, biofilm EVs were unable to damage oral epithelial cells (OECs) but were able to induce cytokine responses. Notably, EVs obtained from biofilms cultured for 24 h and 48 h exhibited differences in cargo composition and their ability to activate OECs. This study highlights the potential of biofilm EVs as a toxin delivery system during <i>C. albicans</i> infection and identifies temporal differences in the ability of EVs to activate epithelial cells.</p>","PeriodicalId":13541,"journal":{"name":"Infection and Immunity","volume":" ","pages":"e0040424"},"PeriodicalIF":2.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12070735/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143763680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>MBOVJF4278_00820</i> encodes a novel cytoadhesin of <i>Mycoplasma bovis</i> binding to heparin.","authors":"Qi Wu, Zhixin Ma, Qiao Pan, Tong Liu, Jiuqing Xin, Qingyuan Xu","doi":"10.1128/iai.00606-24","DOIUrl":"10.1128/iai.00606-24","url":null,"abstract":"<p><p><i>Mycoplasma bovis</i>, a minimal bacterium but a notorious cattle pathogen, leads to serious economic losses. This pathogen binding to host cells is emerging as a complex process involving a broad range of surface-exposed structures. For mycoplasma, adhering to host tissue is the first and crucial step of infection. It is well known that the molecules contributing to microbial cytoadhesion are important virulence factors. Here, we cloned, expressed, and purified the recombinant protein, which is encoded by <i>MBOVJF4278_00820</i>, and induced polyclonal antibodies for it in mice. The cytoadhesive properties of this surface-exposed protein were demonstrated on embryonic bovine lung (EBL) and Madin-Darby bovine kidney (MDBK) cells. Furthermore, heparin as the binding target was confirmed, and the characteristics of the interaction between this protein and heparin have also been analyzed. Our data indicate that the surface-associated <i>MBOVJF4278_00820</i>-encoded protein is a novel adhesion-related factor of <i>Mycoplasma bovis</i>.IMPORTANCEAdhesins are crucial in facilitating <i>Mycoplasma bovis</i> infection. In this study, we identified a specific <i>Mycoplasma bovis</i> adhesin that interacts with heparin on the surface of host cells. Given that heparin is ubiquitously distributed across a wide range of tissue cells, the identification of the heparin-binding adhesin is significant for elucidating how <i>Mycoplasma bovis</i> targets diverse host cells and triggers a spectrum of clinical manifestations.</p>","PeriodicalId":13541,"journal":{"name":"Infection and Immunity","volume":"93 5","pages":"e0060624"},"PeriodicalIF":2.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12070734/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144012953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A <i>Salmonella enterica</i> serovar Typhimurium genome-wide CRISPRi screen reveals a role for type 1 fimbriae in evasion of antibody-mediated agglutination.","authors":"Samantha K Lindberg, Graham G Willsey, Nicholas J Mantis","doi":"10.1128/iai.00574-24","DOIUrl":"10.1128/iai.00574-24","url":null,"abstract":"<p><p>The O5-specific monoclonal IgA antibody, Sal4, mediates the conversion of <i>Salmonella enterica</i> serovar Typhimurium (STm) from virulent, free-swimming cells to non-motile, multicellular biofilm-like aggregates within a matter of hours. We hypothesize that the rapid transition from an invasive to a non-invasive state is an adaptation of STm to Sal4 IgA exposure. In this report, we performed a genome-wide CRISPR interference (CRISPRi) screen to identify STm genes that influence multicellular aggregate formation in response to Sal4 IgA treatment. From a customized library of >36,000 spacers, ~1% (373) were enriched at the top of the culture supernatant after two consecutive rounds of Sal4 IgA treatment. The enriched spacers mapped to a diversity of targets, including genes involved in O-antigen modification, cyclic-di-GMP metabolism, outer membrane biosynthesis/signaling, and invasion/virulence, with the most frequently targeted gene being <i>fimW</i>, which encodes a negative regulator of type 1 fimbriae (T1F) expression. Generation of a STm Δ<i>fimW</i> strain confirmed that the loss of FimW activity results in a hyperfimbriated phenotype and evasion of Sal4 IgA-mediated agglutination in solution. Closer examination of the <i>fimW</i> mutant revealed its propensity to form biofilms at the air-liquid interface in response to Sal4 exposure, suggesting that T1F \"primes\" STm to transition from a planktonic to a sessile state, possibly by facilitating bacterial attachment to abiotic surfaces. These findings shed light on the mechanism by which IgA antibodies influence STm virulence in the intestinal environment.</p>","PeriodicalId":13541,"journal":{"name":"Infection and Immunity","volume":"93 5","pages":"e0057424"},"PeriodicalIF":2.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12070745/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144020563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Involvement of CD146 in the <i>Cryptococcus neoformans</i> adhesion and infection of brain endothelial cells.","authors":"Wei Liu, Junhong Chen, Ting Wang, Ying Gong, Chen Yang, Yuwei Li, Xiyun Yan, Hongxia Duan, Xiaoming Wang, Mingshun Zhang","doi":"10.1128/iai.00145-25","DOIUrl":"10.1128/iai.00145-25","url":null,"abstract":"<p><p>Cryptococcal meningitis is a common and refractory central nervous system (CNS) infection with high mortality and disability. For <i>Cryptococcus neoformans</i> (<i>C. neoformans</i>) to penetrate the CNS, it first adheres to and breaches the blood‒brain barrier (BBB). Here, we explored the roles of CD146, an adhesion molecule expressed on the surface of brain microvascular endothelial cells (BMECs), in cryptococcal vascular adhesion and BBB invasion. Following cryptococcal infection, we observed a reduction in CD146 expression in BMECs, which was at least partially mediated by metalloproteinase-9. Once overexpressed on BMECs, CD146 increased <i>C. neoformans</i> adhesion; in contrast, CD146 knockout decreased the attachment of fungi to endothelial cells <i>in vitro</i>. Unexpectedly, CD146 knockout failed to reduce fungal infection in the brain following intravascular instillation of <i>C. neoformans</i>. However, <i>the</i> anti-CD146 antibody AA98 significantly increased the fungemia (spleen CFU), suggesting that CD146 may be involved in the early adhesion and invasion of Cryptococcus into cerebral vessels. AA98, however, failed to extend the survival of <i>C. neoformans</i> infected mice. These results suggest that CD146 may play dispensable roles in the <i>C. neoformans</i> brain infection.</p>","PeriodicalId":13541,"journal":{"name":"Infection and Immunity","volume":"93 5","pages":"e0014525"},"PeriodicalIF":2.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12070736/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144006592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probiotic colonization of <i>Xenopus laevis</i> skin causes short-term changes in skin microbiomes and gene expression.","authors":"Joseph D Madison, Owen G Osborne, Amy Ellison, Christina N Garvey Griffith, Lindsey Gentry, Harald Gross, Brian Gratwicke, Leon Grayfer, Carly R Muletz-Wolz","doi":"10.1128/iai.00569-24","DOIUrl":"10.1128/iai.00569-24","url":null,"abstract":"<p><p>Probiotic therapies have been suggested for amelioration efforts of wildlife disease such as chytridiomycosis caused by <i>Batrachochytrium</i> spp. in amphibians. However, there is a lack of information on how probiotic application affects resident microbial communities and immune responses. To better understand these interactions, we hypothesized that probiotic application would alter microbial community composition and host immune expression in <i>Xenopus laevis</i>. Accordingly, we applied three amphibian-derived and anti-<i>Batrachochytrium</i> bacteria strains (two <i>Pseudomonas</i> spp. and one <i>Stenotrophomonas</i> sp.) to <i>X. laevis</i> in monoculture and also as a cocktail. We quantified microbial community structure using 16S rRNA gene sequencing. We also quantified genes involved in <i>X. laevis</i> immune responses using quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) and skin transcriptomics over 1 and 3-week periods. All probiotic treatments successfully colonized <i>X. laevis</i> skin for 3 weeks, but with differential amplicon sequence variant (ASV) sequence counts over time. Bacterial community and immune gene effects were most pronounced at week 1 post-probiotic exposure and decreased thereafter. All probiotic treatments caused initial changes to bacterial community alpha and beta diversity, including reduction in diversity from pre-exposure anti-<i>Batrachochytrium</i> bacterial ASV relative abundance. Probiotic colonization by <i>Pseudomonas</i> probiotic strain RSB5.4 reduced expression of regulatory T cell marker (<i>FOXP3,</i> measured with RT-qPCR) and caused the greatest gene expression changes detected by transcriptomics. Single bacterial strains and mixed cultures, therefore, altered amphibian microbiome-immune interactions. This work will help to improve our understanding of the role of the microbiome-immune interface underlying both disease dynamics and emergent eco-evolutionary processes.IMPORTANCEAmphibian skin microbial communities have an important role in determining disease outcomes, in part through complex yet poorly understood interactions with host immune systems. Here we report that probiotic-induced changes to the <i>Xenopus laevis</i> frog skin microbial communities also result in significant alterations to these animals' immune gene expression. These findings underscore the interdependence of amphibian skin immune-microbiome interactions.</p>","PeriodicalId":13541,"journal":{"name":"Infection and Immunity","volume":" ","pages":"e0056924"},"PeriodicalIF":2.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12070741/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143763649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transdifferentiation of neutrophils facilitates the establishment of infection by <i>Leishmania donovani</i> parasites.","authors":"Madhurima Roy, Aniruddha Bagchi, Chaitali Karmakar, Mitali Chatterjee","doi":"10.1128/iai.00409-24","DOIUrl":"https://doi.org/10.1128/iai.00409-24","url":null,"abstract":"<p><p>Neutrophil transdifferentiation involves the acquisition of dendritic cell-like properties, challenging the traditional view of neutrophils being solely phagocytes. The presence of transdifferentiated neutrophils is established in Visceral Leishmaniasis, but not in its dermal sequel, Post Kala-azar Dermal Leishmaniasis. Accordingly, this study investigated the altered functionalities of neutrophils focusing on the acquisition of dendritic cell-like properties and its impact on infection establishment. In PKDL cases, immunophenotyping of neutrophil-dendritic cells (N-DC hybrids) was performed using flow cytometry, along with studying the status of N-DC hybrid inducing cytokines (TNF-α, IFN-γ) and growth factor (GM-CSF). <i>Ex vivo</i> infection of neutrophils with <i>L. donovani</i> was monitored by droplet digital PCR, employing <i>A2</i>; additionally, their frequency of transdifferentiation, oxidative and phagocytic status, as well as apoptosis potential were quantified by flow cytometry. Compared with healthy controls, neutrophils from PKDL cases demonstrated a significant upregulation of CD83 positivity, but the frequency of co-stimulation (HLA-DR, CD80/86) was unaltered. PKDL cases demonstrated raised levels of TNF-α and IFN-γ, but GM-CSF remained unchanged. Following <i>ex vivo</i> infection of neutrophils, infection was evident at 2 h and was accompanied by CD83 positivity. Furthermore, the CD66b⁺/CD83 vis<i>-à-vis</i> CD66b⁺/CD83^- subset exhibited heightened generation of reactive oxygen species (ROS), enhanced phagocytosis, and increased apoptosis. Taken together, neutrophils from PKDL cases demonstrated transdifferentiation with the absence of antigen-presenting function. Virulent <i>Leishmania</i> induced transdifferentiation in neutrophils, altering their functionalities and facilitating parasite uptake, along with heightened generation of intra-neutrophilic ROS and enhanced apoptosis, which possibly facilitated their engulfment by macrophages, thereby bolstering the \"Trojan horse\" mechanism of parasite transfer.</p>","PeriodicalId":13541,"journal":{"name":"Infection and Immunity","volume":" ","pages":"e0040924"},"PeriodicalIF":2.9,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143963374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parenteral vaccination with recombinant EtpA glycoprotein impairs enterotoxigenic <i>E. coli</i> colonization.","authors":"Tim J Vickers, David P Buckley, Nazia Khatoon, Alaullah Sheikh, Bipul Setu, Zachary T Berndsen, James M Fleckenstein","doi":"10.1128/iai.00601-24","DOIUrl":"https://doi.org/10.1128/iai.00601-24","url":null,"abstract":"<p><p>Enterotoxigenic <i>E. coli</i> (ETEC) causes hundreds of millions of cases of acute diarrheal illness in low- and middle-income regions, disproportionately in young children. To date, there is no licensed, broadly protective vaccine against these common but antigenically heterogeneous pathogens. One of the more highly conserved antigens of ETEC, EtpA, is an extracellular glycoprotein adhesin that preferentially binds to A blood group glycans on intestinal epithelia. EtpA contributes to increased severity of illness in A blood group individuals, elicits robust serologic and fecal antibody responses following infection, and has been associated with protection against subsequent infection. However, its utility as a protective antigen needs further examination. In the present studies, we examined whether parenteral vaccination with recombinant EtpA (rEtpA) could afford protection against intestinal colonization in a murine model of ETEC infection. Here, we demonstrate that intramuscular vaccination with rEtpA, adjuvanted with double mutant LT (dmLT), primes IgG predominant mucosal antibody responses to ETEC challenge. Notably, however, both antibody levels and avidity, as well as protection, were dependent on the vaccination schedule. Likewise, through electron microscopy polyclonal epitope mapping (EMPEM), we observed a different repertoire of epitopes targeted by antibodies after a more protracted vaccination schedule. Next, we explored the utility of IM immunization with alum-adjuvanted rEtpA. This elicited strong serologic and fecal IgG responses. Although accompanied by negligible IgA mucosal responses, EtpA alum-adjuvanted IM vaccination nevertheless protected against ETEC intestinal colonization. Collectively, these data suggest that EtpA could expand the portfolio of antigens targeted in ETEC subunit vaccine development.</p>","PeriodicalId":13541,"journal":{"name":"Infection and Immunity","volume":" ","pages":"e0060124"},"PeriodicalIF":2.9,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143989714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phosphatidylserine-binding receptor, CD300f, on macrophages mediates host invasion of pathogenic and non-pathogenic rickettsiae.","authors":"Oliver H Voss, Imran Moin, Hodalis Gaytan, Mohammad Sadik, Saif Ullah, M Sayeedur Rahman","doi":"10.1128/iai.00059-25","DOIUrl":"https://doi.org/10.1128/iai.00059-25","url":null,"abstract":"<p><p>Some arthropod-borne obligate intracellular rickettsiae are among the most virulent human pathogens. <i>Rickettsia</i> species modulate immune (e.g., macrophages; MΦ) and non-immune cell (e.g., endothelial cells) responses to create a habitable environment for host colonization. MΦ play a crucial role in either terminating an infection at an early stage or succumbing to bacterial replication and colonization. However, our understanding of how <i>Rickettsia</i> species invade host cells, including MΦ, remains poorly defined. In this study, we describe a mechanism of host invasion by <i>Rickettsia</i> species, involving rickettsial phosphatidylserine (PS), as a ligand, and the CD300f receptor on MΦ. Our data reveal that engulfment of both pathogenic <i>Rickettsia typhi</i> (the etiologic agent of murine typhus) and <i>Rickettsia rickettsii</i> (the etiologic agent of Rocky Mountain spotted fever) species, as well as the non-pathogenic <i>Rickettsia montanensis</i>, is significantly reduced in bone marrow-derived macrophages (BMDMΦ) from CD300f^-/- mice, as compared to that of wild-type (WT) animals. Furthermore, our mechanistic analysis suggests bacterial PS as the potential source for the CD300f-mediated rickettsiae engulfment by MΦ. <i>In vivo</i> infection studies using WT and CD300f^-/- C57BL/6J mice show that CD300f^-/- animals are protected against <i>R. typhi</i>- or <i>R. rickettsii</i>-induced fatal rickettsiosis, which corroborates with the level of the bacterial burden detected in the spleens of the mice. Adoptive transfer studies reveal that CD300f-expressing MΦ are important mediators to control rickettsiosis <i>in vivo</i>. Collectively, our findings describe a previously unappreciated role for the efferocytic receptor, CD300f, to facilitate engulfment of rickettsiae within the host.</p>","PeriodicalId":13541,"journal":{"name":"Infection and Immunity","volume":" ","pages":"e0005925"},"PeriodicalIF":2.9,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143991854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Xenopus laevis</i> as an infection model for human pathogenic bacteria.","authors":"Ayano Kuriu, Kazuya Ishikawa, Kohsuke Tsuchiya, Kazuyuki Furuta, Chikara Kaito","doi":"10.1128/iai.00126-25","DOIUrl":"https://doi.org/10.1128/iai.00126-25","url":null,"abstract":"<p><p>Animal infection models are essential for understanding bacterial pathogenicity and corresponding host immune responses. In this study, we investigated whether juvenile <i>Xenopus laevis</i> could be used as an infection model for human pathogenic bacteria. <i>Xenopus</i> frogs succumbed to intraperitoneal injection containing the human pathogenic bacteria <i>Staphylococcus aureus</i>, <i>Pseudomonas aeruginosa</i>, and <i>Listeria monocytogenes</i>. In contrast, non-pathogenic bacteria <i>Bacillus subtilis</i> and <i>Escherichia coli</i> did not induce mortality in <i>Xenopus</i> frogs. The administration of appropriate antibiotics suppressed mortality caused by <i>S. aureus</i> and <i>P. aeruginosa</i>. Strains lacking the <i>agr</i> locus, <i>cvfA</i> (<i>rny</i>) gene, or hemolysin genes in <i>S. aureus</i>, LIPI-1-deleted mutant of <i>L. monocytogenes</i>, which attenuate virulence within mammals, exhibited reduced virulence in <i>Xenopus</i> frogs compared with their respective wild-type counterparts. Bacterial distribution analysis revealed that <i>S. aureus</i> persisted in the blood, liver, heart, and muscles of <i>Xenopus</i> frogs until death. These results suggested that intraperitoneal injection of human pathogenic bacteria induces sepsis-like symptoms in <i>Xenopus</i> frogs, supporting their use as a valuable animal model for evaluating antimicrobial efficacy and identifying virulence genes in various human pathogenic bacteria.</p>","PeriodicalId":13541,"journal":{"name":"Infection and Immunity","volume":" ","pages":"e0012625"},"PeriodicalIF":2.9,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143965149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insights on the regulation and function of the CRISPR/Cas transposition system located in the pathogenicity island VpaI-7 from <i>Vibrio parahaemolyticus</i> RIMD2210633.","authors":"Jesús E Alejandre-Sixtos, Kebia Aguirre-Martínez, Jessica Cruz-López, Aliandi Mares-Rivera, Samanda M Álvarez-Martínez, David Zamorano-Sánchez","doi":"10.1128/iai.00169-25","DOIUrl":"https://doi.org/10.1128/iai.00169-25","url":null,"abstract":"<p><p>CRISPR/Cas-mediated transposition is a recently recognized strategy for horizontal gene transfer in a variety of bacterial species. However, our understanding of the factors that control their function in their natural hosts is still limited. In this work, we report our initial genetic characterization of the elements associated with the CRISPR/Cas-transposition machinery (CASTm) from <i>Vibrio parahaemolyticus</i> (<i>Vpa</i>CASTm), which are encoded within the pathogenicity island VpaI-7. Our results revealed that the components of the <i>Vpa</i>CASTm and their associated CRISPR arrays (<i>Vpa</i>CAST system) are transcriptionally active in their native genetic context. Furthermore, we were able to detect the presence of polycistrons and several internal promoters within the loci that compose the <i>Vpa</i>CAST system. Our results also suggest that the activity of the promoter of the atypical CRISPR array is not repressed by the baseline activity of its known regulator VPA1391 in <i>V. parahaemolyticus</i>. In addition, we found that the activity of the promoter of <i>tniQ</i> was modulated by a regulatory cascade involving ToxR, LeuO, and H-NS. Since it was previously reported that the activity of the <i>Vpa</i>CAST system was less efficient than that of the <i>Vch</i>CAST system at promoting transposition of a miniaturized CRISPR-associated transposon (mini-CAST) in <i>Escherichia coli</i>, we analyzed if the transposition efficiency mediated by the <i>Vpa</i>CAST system could be enhanced inside its natural host <i>V. parahaemolyticus</i>. We provide evidence that this might be the case, suggesting that there could be host induction factors in <i>V. parahaemolyticus</i> that could enable more efficient transposition of CASTs.IMPORTANCEMobile genetic elements such as transposons play important roles in the evolutionary trajectories of bacterial genomes. The success of transposon dissemination depends on their ability to carry selectable markers that improve the fitness of the host cell or loci with addictive traits such as the toxin-antitoxin systems. Here we aimed to characterize a transposon from <i>Vibrio parahaemolyticus</i> that carries and could disseminate multiple virulence factors. This transposon belongs to a recently discovered family of transposons whose transposition is guided by crRNA. We showed that the transposition machinery of this transposon is transcribed in <i>V. parahaemolyticus</i> and that there are likely host-associated factors that favor transposition in the natural host <i>V. parahaemolyticus</i> over transposition in <i>Escherichia coli</i>.</p>","PeriodicalId":13541,"journal":{"name":"Infection and Immunity","volume":" ","pages":"e0016925"},"PeriodicalIF":2.9,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144014869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}