Identification of homologs of the Chlamydia trachomatis effector CteG reveals a family of Chlamydiaceae type III secreted proteins that can be delivered into host cells.

Chlamydiae are a large group of obligate endosymbionts of eukaryotes that includes the Chlamydiaceae family, comprising several animal pathogens. Among Chlamydiaceae, Chlamydia trachomatis causes widespread ocular and urogenital infections in humans. Like many bacterial pathogens, all Chlamydiae manipulate host cells by injecting them with type III secretion effector proteins. We previously characterized the C. trachomatis effector CteG, which localizes at the host cell Golgi and plasma membrane during distinct phases of the chlamydial infectious cycle. Here, we show that CteG is a Chlamydiaceae-specific effector with over 60 homologs phylogenetically categorized into two distinct clades (CteG I and CteG II) and exhibiting several inparalogs and outparalogs. Notably, cteG I homologs are syntenic to C. trachomatis cteG, whereas cteG II homologs are syntenic among themselves but not with C. trachomatis cteG. This indicates a complex evolution of cteG homologs, which is unique among C. trachomatis effectors, marked by numerous events of gene duplication and loss. Despite relatively modest sequence conservation, nearly all tested CteG I and CteG II proteins were identified as type III secretion substrates using Yersinia as a heterologous bacterial host. Moreover, most of the type III secreted CteG I and CteG II homologs were delivered by C. trachomatis into host cells, where they localized at the Golgi region and cell periphery. Overall, this provided insights into the evolution of bacterial effectors and revealed a Chlamydiaceae family of type III secreted proteins that underwent substantial divergence during evolution while conserving the capacity to localize at specific host cell compartments.

Insights into the genomic traits of Yersinia frederiksenii, Yersinia intermedia and Yersinia kristensenii isolated from diverse sources in Brazil.

Yersinia is an important genus comprising foodborne, zoonotic and pathogenic bacteria. On the other hand, species of the so-called group Yersinia enterocolitica-like are understudied and mostly characterized as non-pathogenic, despite of some reports of human infections. The present study aimed to provide genomic insights of Yersinia frederiksenii (YF), Yersinia intermedia (YI) and Yersinia kristensenii (YK) isolated worldwide. A total of 22 YF, 20 YI and 14 YK genomes were searched for antimicrobial resistance genes, plasmids, prophages, and virulence factors. Their phylogenomic relatedness was analyzed by Gegenees and core-genome multi-locus sequence typing. Beta-lactam resistance gene blaTEM-116 and five plasmids replicons (pYE854, ColRNAI, ColE10, Col(pHAD28) and IncN3) were detected in less than five genomes. A total of 59 prophages, 106 virulence markers of the Yersinia genus, associated to adherence, antiphagocytosis, exoenzymes, invasion, iron uptake, proteases, secretion systems and the O-antigen, and virulence factors associated to other 20 bacterial genera were detected. Phylogenomic analysis revealed high inter-species distinction and four highly diverse YF clusters. In conclusion, the results obtained through the analyses of YF, YI and YK genomes suggest the virulence potential of these strains due to the broad diversity and high frequency of prophages and virulence factors found. Phylogenetic analyses were able to correctly distinguish these closely related species and show the presence of different genetic subgroups. These data contributed for a better understanding of YF, YI and YK virulence-associated features and global genetic diversity, and reinforced the need for better characterization of these Y. enterocolitica-like species considered non-pathogenic.

Tyrosine-modifying glycosylation by Yersinia effectors.

Mono-O-glycosylation of target proteins by bacterial toxins or effector proteins is a well-known mechanism by which bacteria interfere with essential functions of host cells. The respective glycosyltransferases are important virulence factors such as the Clostridioides difficile toxins A and B. Here, we describe two glycosyltransferases of Yersinia species that have a high sequence identity: YeGT from the zoonotic pathogen Yersinia enterocolitica and YkGT from the murine pathogen Yersinia kristensenii. We show that both modify Rho family proteins by attachment of GlcNAc at tyrosine residues (Tyr-34 in RhoA). Notably, the enzymes differed in their target protein specificity. While YeGT modified RhoA, B, and C, YkGT possessed a broader substrate spectrum and glycosylated not only Rho but also Rac and Cdc42 subfamily proteins. Mutagenesis studies indicated that residue 177 is important for this broader target spectrum. We determined the crystal structure of YeGT shortened by 16 residues N terminally (sYeGT) in the ligand-free state and bound to UDP, the product of substrate hydrolysis. The structure assigns sYeGT to the GT-A family. It shares high structural similarity to glycosyltransferase domains from toxins. We also demonstrated that the 16 most N-terminal residues of YeGT and YkGT are important for the mediated translocation into the host cell using the pore-forming protective antigen of anthrax toxin. Mediated introduction into HeLa cells or ectopic expression of YeGT and YkGT caused morphological changes and redistribution of the actin cytoskeleton. The data suggest that YeGT and YkGT are likely bacterial effectors belonging to the family of tyrosine glycosylating bacterial glycosyltransferases.

The ABC toxin complex from Yersinia entomophaga can package three different cytotoxic components expressed from distinct genetic loci in an unfolded state: the structures of both shell and cargo.

Bacterial ABC toxin complexes (Tcs) comprise three core proteins: TcA, TcB and TcC. The TcA protein forms a pentameric assembly that attaches to the surface of target cells and penetrates the cell membrane. The TcB and TcC proteins assemble as a heterodimeric TcB-TcC subcomplex that makes a hollow shell. This TcB-TcC subcomplex self-cleaves and encapsulates within the shell a cytotoxic `cargo' encoded by the C-terminal region of the TcC protein. Here, we describe the structure of a previously uncharacterized TcC protein from Yersinia entomophaga, encoded by a gene at a distant genomic location from the genes encoding the rest of the toxin complex, in complex with the TcB protein. When encapsulated within the TcB-TcC shell, the C-terminal toxin adopts an unfolded and disordered state, with limited areas of local order stabilized by the chaperone-like inner surface of the shell. We also determined the structure of the toxin cargo alone and show that when not encapsulated within the shell, it adopts an ADP-ribosyltransferase fold most similar to the catalytic domain of the SpvB toxin from Salmonella typhimurium. Our structural analysis points to a likely mechanism whereby the toxin acts directly on actin, modifying it in a way that prevents normal polymerization.

Pathogenicity and virulence of Yersinia.

The genus Yersinia includes human, animal, insect, and plant pathogens as well as many symbionts and harmless bacteria. Within this genus are Yersinia enterocolitica and the Yersinia pseudotuberculosis complex, with four human pathogenic species that are highly related at the genomic level including the causative agent of plague, Yersinia pestis. Extensive laboratory, field work, and clinical research have been conducted to understand the underlying pathogenesis and zoonotic transmission of these pathogens. There are presently more than 500 whole genome sequences from which an evolutionary footprint can be developed that details shared and unique virulence properties. Whereas the virulence of Y. pestis now seems in apparent homoeostasis within its flea transmission cycle, substantial evolutionary changes that affect transmission and disease severity continue to ndergo apparent selective pressure within the other Yersiniae that cause intestinal diseases. In this review, we will summarize the present understanding of the virulence and pathogenesis of Yersinia, highlighting shared mechanisms of virulence and the differences that determine the infection niche and disease severity.

Yersinia entomophaga Tc toxin is released by T10SS-dependent lysis of specialized cell subpopulations.

Disease-causing bacteria secrete numerous toxins to invade and subjugate their hosts. Unlike many smaller toxins, the secretion machinery of most large toxins remains enigmatic. By combining genomic editing, proteomic profiling and cryo-electron tomography of the insect pathogen Yersinia entomophaga, we demonstrate that a specialized subset of these cells produces a complex toxin cocktail, including the nearly ribosome-sized Tc toxin YenTc, which is subsequently exported by controlled cell lysis using a transcriptionally coupled, pH-dependent type 10 secretion system (T10SS). Our results dissect the Tc toxin export process by a T10SS, identifying that T10SSs operate via a previously unknown lytic mode of action and establishing them as crucial players in the size-insensitive release of cytoplasmically folded toxins. With T10SSs directly embedded in Tc toxin operons of major pathogens, we anticipate that our findings may model an important aspect of pathogenesis in bacteria with substantial impact on agriculture and healthcare.

Whole-genome sequencing-based analysis of antimicrobial resistance, virulence factors, and genetic diversity in Yersinia isolated in Wenzhou, China 2020.

Yersinia spp. vary significantly in their ability to cause diseases that threaten public health. Their pathogenicity is frequently associated with increasing antimicrobial resistance (AMR) and various virulence factors. The aim of the study was to investigate the AMR genes, virulence factors, and genetic diversity of Yersinia strains isolated from meats and fish in Wenzhou in 2020 by using whole-genome sequencing (WGS). A total of 50 isolates were collected. The phylogenetic relationships among the Yersinia species were also analyzed using multilocus sequence typing (MLST), core genome multi-locus sequence typing (cgMLST), and single nucleotide polymorphism (SNP) analysis. According to the results, all the strains could be classified into five species, with most isolated from beef, followed by poultry, pork, and fish. AMR genes were identified in 23 strains. And the qnrD1 genes were all located in the Col3M plasmid. Virulence genes, such as yaxA, ystB, pla, and yplA, were also found in the 15 Y. enterocolitica strains. And this study also found the presence of icm/dot type IVB-related genes in one Yersinia massiliensis isolate. MLST analysis identified 43 sequence types (STs), 19 of which were newly detected in Yersinia. Moreover, cgMLST analysis revealed that no dense genotype clusters were formed (cgMLST 5341, 5344, 5346-5350, 5353-5390). Instead, the strains appeared to be dispersed over large distances, except when multiple isolates shared the same ST. Isolates Y4 and Y26 were closely related to strains originating from South Korea and Denmark. This study showed considerable diversity in Yersinia spp. isolated from local areas (Wenzhou City). The data generated in our study may enrich the molecular traceability database of Yersinia and provide a basis for the development of more effective antipathogen control strategies.

Development of detection methods by multiplex real-time PCR for highly pathogenic Yersinia enterocolitica, low pathogenic Yersinia enterocolitica, and Yersinia pseudotuberculosis based on SYBR Green and TaqMan probes.

This study aimed to develop multiplex real-time PCR methods using SYBR Green and TaqMan probes for rapid and sensitive diagnosis, differentiating three pathogenic Yersinia groups such as highly pathogenic Y. enterocolitica, low pathogenic Y. enterocolitica, and Y. pseudotuberculosis. Specific primer and probe combinations for differentiating three pathogenic Yersinia groups were designed from three chromosomally encoded genes (ail, fyuA, and inv). Twenty-six stains of pathogenic Yersinia species including 6 strains of low pathogenic Y. enterocolitica serotypes, 7 strains of highly pathogenic Y. enterocolitica serotypes, and 13 strains of pathogenic Y. pseudotuberculosis were used for specificity testing. Specific patterns of real-time amplification signals distinguished three pathogenic Yersinia groups. A detection limit of approximately 101 colony forming units (CFU) /reaction of genomic DNA was determined based on plate counts. Furthermore, the multiplex real-time PCR methods also detected Y. enterocolitica O:8 from the DNA extracted from spiked rabbit blood samples and potentially infected wild rodent fecal samples. These results demonstrated that the multiplex real-time PCR methods developed in this study are useful for rapid detection and differentiation of three pathogenic Yersinia groups. Therefore, these methods provide a new monitoring and detection capability to understand the epidemiology of pathogenic Yersinia and to diagnose three pathogenic Yersinia groups.

A ParDE toxin-antitoxin system is responsible for the maintenance of the Yersinia virulence plasmid but not for type III secretion-associated growth inhibition.

Many Gram-negative pathogens utilize the type III secretion system (T3SS) to translocate virulence-promoting effector proteins into eukaryotic host cells. The activity of this system results in a severe reduction of bacterial growth and division, summarized as secretion-associated growth inhibition (SAGI). In Yersinia enterocolitica, the T3SS and related proteins are encoded on a virulence plasmid. We identified a ParDE-like toxin-antitoxin system on this virulence plasmid in genetic proximity to yopE, encoding a T3SS effector. Effectors are strongly upregulated upon activation of the T3SS, indicating a potential role of the ParDE system in the SAGI or maintenance of the virulence plasmid. Expression of the toxin ParE in trans resulted in reduced growth and elongated bacteria, highly reminiscent of the SAGI. Nevertheless, the activity of ParDE is not causal for the SAGI. T3SS activation did not influence ParDE activity; conversely, ParDE had no impact on T3SS assembly or activity itself. However, we found that ParDE ensures the presence of the T3SS across bacterial populations by reducing the loss of the virulence plasmid, especially under conditions relevant to infection. Despite this effect, a subset of bacteria lost the virulence plasmid and regained the ability to divide under secreting conditions, facilitating the possible emergence of T3SS-negative bacteria in late acute and persistent infections.

Repression by the H-NS/YmoA histone-like protein complex enables IscR dependent regulation of the Yersinia T3SS.

The type III secretion system (T3SS) is an appendage used by many bacterial pathogens, such as pathogenic Yersinia, to subvert host defenses. However, because the T3SS is energetically costly and immunogenic, it must be tightly regulated in response to environmental cues to enable survival in the host. Here we show that expression of the Yersinia Ysc T3SS master regulator, LcrF, is orchestrated by the opposing activities of the repressive H-NS/YmoA histone-like protein complex and induction by the iron and oxygen-regulated IscR transcription factor. While deletion of iscR or ymoA has been shown to decrease and increase LcrF expression and type III secretion, respectively, the role of H-NS in this system has not been definitively established because hns is an essential gene in Yersinia. Using CRISPRi knockdown of hns, we show that hns depletion causes derepression of lcrF. Furthermore, we find that while YmoA is dispensable for H-NS binding to the lcrF promoter, YmoA binding to H-NS is important for H-NS repressive activity. We bioinformatically identified three H-NS binding regions within the lcrF promoter and demonstrate binding of H-NS to these sites in vivo using chromatin immunoprecipitation. Using promoter truncation and binding site mutation analysis, we show that two of these H-NS binding regions are important for H-NS/YmoA-mediated repression of the lcrF promoter. Surprisingly, we find that IscR is dispensable for lcrF transcription in the absence of H-NS/YmoA. Indeed, IscR-dependent regulation of LcrF and type III secretion in response to changes in oxygen, such as those Yersinia is predicted to experience during host infection, only occurs in the presence of an H-NS/YmoA complex. These data suggest that, in the presence of host tissue cues that drive sufficient IscR expression, IscR can act as a roadblock to H-NS/YmoA-dependent repression of RNA polymerase at the lcrF promoter to turn on T3SS expression.

Host Range, Morphology and Sequence Analysis of Ten Temperate Phages Isolated from Pathogenic Yersinia enterocolitica Strains.

Yersinia enterocolitica is a heterogeneous species comprising highly pathogenic, weakly pathogenic and non-pathogenic strains. Previous data suggest that gene exchange may occur in Yersinia. Only scarce information exists about temperate phages of Y. enterocolitica, even though many prophage sequences are present in this species. We have examined 102 pathogenic Y. enterocolitica strains for the presence of inducible prophages by mitomycin C treatment. Ten phages were isolated from nine strains belonging to the bio (B)/serotypes (O) B2/O:5,27, B2/O:9 and 1B/O:8. All phages are myoviruses showing lytic activity only at room temperature. Whole-genome sequencing of the phage genomes revealed that they belong to three groups, which, however, are not closely related to known phages. Group 1 is composed of five phages (type phage: vB_YenM_06.16.1) with genome sizes of 43.8 to 44.9 kb, whereas the four group 2 phages (type phage: vB_YenM_06.16.2) possess smaller genomes of 29.5 to 33.2 kb. Group 3 contains only one phage (vB_YenM_42.18) whose genome has a size of 36.5 kb, which is moderately similar to group 2. The host range of the phages differed significantly. While group 1 phages almost exclusively lysed strains of B2/O:5,27, phages of group 2 and 3 were additionally able to lyse B4/O:3, and some of them even B2/O:9 and 1B/O:8 strains.

YsHyl8A, an Alkalophilic Cold-Adapted Glycosaminoglycan Lyase Cloned from Pathogenic Yersinia sp. 298.

A high enzyme-yield strain Yersinia sp. 298 was screened from marine bacteria harvested from the coastal water. The screening conditions were extensive, utilizing hyaluronic acid (HA)/chondroitin sulfate (CS) as the carbon source. A coding gene yshyl8A of the family 8 polysaccharide lyase (PL8) was cloned from the genome of Yersinia sp. 298 and subjected to recombinant expression. The specific activity of the recombinase YsHyl8A was 11.19 U/mg, with an optimal reaction temperature of 40 °C and 50% of its specific activity remaining after thermal incubation at 30 °C for 1 h. In addition, its optimal reaction pH was 7.5, and while it was most stable at pH 6.0 in Na2HPO4-citric acid buffer, it remained highly stable at pH 6.0-11.0. Further, its enzymatic activity was increased five-fold with 0.1 M NaCl. YsHyl8A, as an endo-lyase, can degrade both HA and CS, producing disaccharide end-products. These properties suggested that YsHyl8A possessed both significant alkalophilic and cold-adapted features while being dependent on NaCl, likely resulting from its marine source. Yersinia is a typical fish pathogen, with glycosaminoglycan lyase (GAG lyase) as a potential pathogenic factor, exhibiting strong hyaluronidase and chondroitinase activity. Further research on the pathogenic mechanism of GAG lyase may benefit the prevention and treatment of related diseases.

The Yersinia High-Pathogenicity Island Encodes a Siderophore-Dependent Copper Response System in Uropathogenic Escherichia coli.

Siderophores are iron chelators used by microbes to bind and acquire iron, which, once in the cell, inhibits siderophore production through feedback repression mediated by the ferric uptake repressor (Fur). Yersiniabactin (Ybt), a siderophore associated with enhanced pathogenic potential among Enterobacteriaceae, also binds copper ions during human and experimental murine infections. In contrast to iron, we found that extracellular copper ions rapidly and selectively stimulate Ybt production in extraintestinal pathogenic Escherichia coli. The stimulatory pathway requires formation of an extracellular copper-Ybt (Cu(II)-Ybt) complex, internalization of Cu(II)-Ybt entry through the canonical TonB-dependent outer membrane transporter, and Fur-independent transcriptional regulation by the specialized transcription factor YbtA. Dual regulation by iron and copper is consistent with a multifunctional metallophore role for Ybt. Feed-forward regulation is typical of stress responses, implicating Ybt in prevention of, or response to, copper stress during infection pathogenesis. IMPORTANCE Interactions between bacteria and transition metal ions play an important role in encounters between humans and bacteria. Siderophore systems have long been prominent mediators of these interactions. These systems secrete small-molecule chelators that bind oxidized iron(III) and express proteins that specifically recognize and import these complexes as a nutritional iron source. While E. coli and other Enterobacteriaceae secrete enterobactin, clinical isolates often secrete an additional siderophore, yersiniabactin (Ybt), which has been found to also bind copper and other non-iron metal ions. The observation here that an extraintestinal E. coli isolate secretes Ybt in a copper-inducible manner suggests an important gain of function over the enterobactin system. Copper recognition involves using Ybt to bind Cu(II) ions, consistent with a distinctively extracellular mode of copper detection. The resulting Cu(II)-Ybt complex signals upregulation of Ybt biosynthesis genes as a rapid response against potentially toxic extracellular copper ions. The Ybt system is distinguishable from other copper response systems that sense cytosolic and periplasmic copper ions. The Ybt dependence of the copper response presents an implicit feed-forward regulatory scheme that is typical of bacterial stress responses. The distinctive extracellular copper recognition-response functionality of the Ybt system may enhance the pathogenic potential of infection-associated Enterobacteriaceae.

Identification of genes involved in exoprotein release using a high-throughput exoproteome screening assay in Yersinia entomophaga.

Bacterial protein secretion is crucial to the maintenance of viability and pathogenicity. Although many bacterial secretion systems have been identified, the underlying mechanisms regulating their expression are less well explored. Yersinia entomophaga MH96, an entomopathogenic bacterium, releases an abundance of proteins including the Yen-Tc into the growth medium when cultured in Luria Bertani broth at ≤ 25°C. Through the development of a high-throughput exoproteome screening assay (HESA), genes involved in MH96 exoprotein production were identified. Of 4,080 screened transposon mutants, 34 mutants exhibited a decreased exoprotein release, and one mutation located in the intergenic region of the Yen-Tc operon displayed an elevated exoprotein release relative to the wild-type strain MH96. DNA sequencing revealed several transposon insertions clustered in gene regions associated with lipopolysaccharide (LPSI and LPSII), and N-acyl-homoserine lactone synthesis (quorum sensing). Twelve transposon insertions were located within transcriptional regulators or intergenic regions. The HESA will have broad applicability for identifying genes associated with exoproteome production in a range of microorganisms.

Yersinia massiliensis (Enterobacteriales: Enterobacteriaceae) in the host Anaphes nitens (Hymenoptera: Mymaridae): first report of association with insects / Yersinia massiliensis (Enterobacteriales: Enterobacteriaceae) no hospedeiro Anaphes nitens (Hymenoptera: Mymaridae): primeiro relato de associação com insetos

Endosymbiont bacteria can affect biological parameters and reduce the effectiveness of natural enemies in controlling the target insect. The objective of this work was to identify endosymbiont bacteria in Anaphes nitens (Girault, 1928) (Hymenoptera: Mymaridae), the main natural enemy used to manage Gonipterus platensis (Marelli, 1926) (Coleoptera: Curculionidae). Genomic DNA from six A. nitens populations was extracted and polymerase chain reactions (PCR) were performed with the primers to detect endosymbiont bacteria in this insect. The PCR products were amplified, sequenced, and compared with sequences deposited in the GenBank for the bacteria identification. All A. nitens populations had the bacterium Yersinia massiliensis (Enterobacteriales: Enterobacteriaceae). This bacterium was originally described as free-living, and it is associated with and composes part of the A. nitens microbiota. This is the first report of Y. massiliensis in an insect host.

As bactérias endossimbiontes podem afetar os parâmetros biológicos e reduzirem a eficácia de inimigos naturais no controle do inseto alvo. O objetivo deste trabalho foi identificar bactérias endossimbiontes em Anaphes nitens (Girault, 1928) (Hymenoptera: Mymaridae), o principal inimigo natural usado no manejo de Gonipterus platensis (Marelli, 1926) (Coleoptera: Curculionidae). O DNA genômico de seis populações de A. nitens foi extraído e as reações em cadeia da polimerase (PCR) realizadas com os primers para detectar bactérias endossimbiontes neste inseto. Os produtos de PCR foram amplificados, sequenciados e comparados com as sequências depositadas no GenBank para identificação das bactérias. Todas as populações de A. nitens tinham a bactéria Yersinia massiliensis (Enterobacteriales: Enterobacteriaceae). Esta bactéria foi originalmente descrita como de vida livre e está associada e compõe parte da microbiota de A. nitens. Este é o primeiro relato de Y. massiliensis em um hospedeiro.

Effector-mediated membrane disruption controls cell death in CBASS antiphage defense.

Cyclic oligonucleotide-based antiphage signaling systems (CBASS) are antiviral defense operons that protect bacteria from phage replication. Here, we discover a widespread class of CBASS transmembrane (TM) effector proteins that respond to antiviral nucleotide signals and limit phage propagation through direct membrane disruption. Crystal structures of the Yersinia TM effector Cap15 reveal a compact 8-stranded ß-barrel scaffold that forms a cyclic dinucleotide receptor domain that oligomerizes upon activation. We demonstrate that activated Cap15 relocalizes throughout the cell and specifically induces rupture of the inner membrane. Screening for active effectors, we identify the function of distinct families of CBASS TM effectors and demonstrate that cell death via disruption of inner-membrane integrity is a common mechanism of defense. Our results reveal the function of the most prominent class of effector protein in CBASS immunity and define disruption of the inner membrane as a widespread strategy of abortive infection in bacterial phage defense.

BtuB-Dependent Infection of the T5-like Yersinia Phage ϕR2-01.

Yersinia enterocolitica is a food-borne Gram-negative pathogen responsible for several gastrointestinal disorders. Host-specific lytic bacteriophages have been increasingly used recently as an alternative or complementary treatment to combat bacterial infections, especially when antibiotics fail. Here, we describe the proteogenomic characterization and host receptor identification of the siphovirus vB_YenS_ϕR2-01 (in short, ϕR2-01) that infects strains of several Yersinia enterocolitica serotypes. The ϕR2-01 genome contains 154 predicted genes, 117 of which encode products that are homologous to those of Escherichia bacteriophage T5. The ϕR2-01 and T5 genomes are largely syntenic, with the major differences residing in areas encoding hypothetical ϕR2-01 proteins. Label-free mass-spectrometry-based proteomics confirmed the expression of 90 of the ϕR2-01 genes, with 88 of these being either phage particle structural or phage-particle-associated proteins. In vitro transposon-based host mutagenesis and ϕR2-01 adsorption experiments identified the outer membrane vitamin B12 receptor BtuB as the host receptor. This study provides a proteogenomic characterization of a T5-type bacteriophage and identifies specific Y. enterocolitica strains sensitive to infection with possible future applications of ϕR2-01 as a food biocontrol or phage therapy agent.

Virulence genes identification and characterization revealed the presence of the Yersinia High Pathogenicity Island (HPI) in Salmonella from Brazil.

Salmonella spp. is one of the major agents of foodborne disease worldwide, and its virulence genes are responsible for the main pathogenic mechanisms of this micro-organism. The whole-genome sequencing (WGS) of pathogens has become a lower-cost and more accessible genotyping tool providing many gene analysis possibilities. This study provided an in silico investigation of 129 virulence genes, including plasmidial and bacteriophage genes from Brazilian strains' public Salmonella genomes. The frequency analysis of the four most sequenced serovars and a temporal analysis over the past four decades was also performed. The NCBI sequence reads archive (SRA) database comprised 1077 Salmonella public whole-genome sequences of strains isolated in Brazil between 1968 and 2018. Among the 1077 genomes, 775 passed in Salmonella in silico Typing (SISTR) quality control, which also identified 41 different serovars in which the four most prevalent were S. Enteritidis, S. Typhimurium, S. Dublin, and S. Heidelberg. Among these, S. Heidelberg presented the most distinct virulence profile, besides presenting Yersinia High Pathogenicity Island (HPI), rare and first reported in Salmonella from Brazil. The genes mgtC, csgC, ssaI and ssaS were the most prevalent within the 775 genomes with more than 99% prevalence. On the other hand, the less frequent genes were astA, iucBCD, tptC and shdA, with less than 1% frequency. All of the plasmids and bacteriophages virulence genes presented a decreasing trend between the 2000 s and 2010 s decades, except for the phage gene grvA, which increased in this period. This study provides insights into Salmonella virulence genes distribution in Brazil using freely available bioinformatics tools. This approach could guide in vivo and in vitro studies besides being an interesting method for the investigation and surveillance of Salmonella virulence. Moreover, here we propose the genes mgtC, csgC, ssaI and ssaS as additional targets for PCR identification of Salmonella in Brazil due to their very high frequency in the studied genomes.

Yersinia massiliensis (Enterobacteriales: Enterobacteriaceae) in the host Anaphes nitens (Hymenoptera: Mymaridae): first report of association with insects.

Endosymbiont bacteria can affect biological parameters and reduce the effectiveness of natural enemies in controlling the target insect. The objective of this work was to identify endosymbiont bacteria in Anaphes nitens (Girault, 1928) (Hymenoptera: Mymaridae), the main natural enemy used to manage Gonipterus platensis (Marelli, 1926) (Coleoptera: Curculionidae). Genomic DNA from six A. nitens populations was extracted and polymerase chain reactions (PCR) were performed with the primers to detect endosymbiont bacteria in this insect. The PCR products were amplified, sequenced, and compared with sequences deposited in the GenBank for the bacteria identification. All A. nitens populations had the bacterium Yersinia massiliensis (Enterobacteriales: Enterobacteriaceae). This bacterium was originally described as free-living, and it is associated with and composes part of the A. nitens microbiota. This is the first report of Y. massiliensis in an insect host.

In vivo transcriptome analysis provides insights into host-dependent expression of virulence factors by Yersinia entomophaga MH96, during infection of Galleria mellonella.

The function of microbes can be inferred from knowledge of genes specifically expressed in natural environments. Here, we report the in vivo transcriptome of the entomopathogenic bacterium Yersinia entomophaga MH96, captured during initial, septicemic, and pre-cadaveric stages of intrahemocoelic infection in Galleria mellonella. A total of 1285 genes were significantly upregulated by MH96 during infection; 829 genes responded to in vivo conditions during at least one stage of infection, 289 responded during two stages of infection, and 167 transcripts responded throughout all three stages of infection compared to in vitro conditions at equivalent cell densities. Genes upregulated during the earliest infection stage included components of the insecticidal toxin complex Yen-TC (chi1, chi2, and yenC1), genes for rearrangement hotspot element containing protein yenC3, cytolethal distending toxin cdtAB, and vegetative insecticidal toxin vip2. Genes more highly expressed throughout the infection cycle included the putative heat-stable enterotoxin yenT and three adhesins (usher-chaperone fimbria, filamentous hemagglutinin, and an AidA-like secreted adhesin). Clustering and functional enrichment of gene expression data also revealed expression of genes encoding type III and VI secretion system-associated effectors. Together these data provide insight into the pathobiology of MH96 and serve as an important resource supporting efforts to identify novel insecticidal agents.