Francisella salimarina infection in farmed cobia (Rachycentron canadum) and dusky grouper (Epinephelus marginatus) in Brazil: A case report.

This study aimed to identify and characterize isolates of Francisella salimarina associated with an outbreak on a marine fish farm in Brazil and to analyse their genetic variability and antimicrobial susceptibility. In 2021, diseased cobias (Rachycentron canadum, n = 10) and dusky groupers (Epinephelus marginatus, n = 10) were sampled and subjected to bacteriological and pathological examinations. The isolates obtained were morphologically and biochemically characterized and identified by matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) and 16S rRNA gene sequencing. The genetic diversity of these isolates was analysed using repetitive extragenic palindromic-polymerase chain reaction (REP-PCR). Antimicrobial susceptibility was assessed using the disk diffusion technique. Macroscopically, the fish presented skin ulcerations, ocular lesions, hepatomegaly and splenomegaly. A pleomorphic, gram-negative, catalase- and oxidase-positive bacterium was isolated from seven cobias and two groupers. The 16S rRNA gene sequences showed >99% coverage and identity with other deposited sequences of F. salimarina. The results of the biochemical analysis corresponded to these bacterial species. Histologically, granulomas were observed in the spleen, liver and heart of the cobias (n = 6), and necrotizing and fibrinous dermatitis and myositis were identified in some groupers (n = 2). The isolates exhibited the same banding pattern when REP-PCR was performed, indicating that they were clonally related. Finally, the antibiogram test, no inhibition halo was observed for amoxicillin and trimethoprim-sulfamethoxazole. To our knowledge, this is the first report of F. salimarina infection in cobias and dusky groupers.

Edwardsiella tarda in Tambaqui (Colossoma macropomum): A Pathogenicity, Antimicrobial Susceptibility, and Genetic Analysis of Brazilian Isolates.

Edwardsiella tarda is a crucial pathogenic bacterium in tropical aquaculture. This bacterium was recently isolated from tambaqui (Colossoma macropomum), a commercially important fish species in Brazil. This study assessed the antimicrobial susceptibility, pathogenicity, and genetic diversity of the tambaqui-derived E. tarda isolates. Fourteen bacterial isolates isolated from tambaqui were identified as E. tarda by using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry and dnaJ gene sequencing. Antimicrobial susceptibility tests were conducted against seven drugs using the disc diffusion assay. The pathogenicity test conducted by intraperitoneal injection of 2.4 × 107 colony-forming units (CFU) fish-1 of E. tarda (ED38-17) into tambaqui juveniles eventually revealed that neither clinical signs nor death were present. However, splenomegaly and whitish areas in the spleen and kidneys were observed. The histological investigation also revealed granulomatous splenitis, nephritis, and hepatitis occurring internally. Repetitive extragenic palindromic-PCR fingerprinting separated the 14 isolates into three genetic groups. The antibiogram revealed that all E. tarda isolates were wild-type (WT) to florfenicol (FLO), norfloxacin (NOR), neomycin (NEO), erythromycin (ERY), and oxytetracycline (OXY); however, some were non-wild-type to sulfamethoxazole/trimethoprim (7.1%) and amoxicillin (21.4%). Therefore, through experimental infection, E. tarda ED38-17 could induce pathogenic effects in C. macropomum. Additionally, three distinct genetic types were found, and the E. tarda isolates were WT to FLO, NOR, NEO, ERY, and OXY. These findings raise awareness of a bacteria causing unseen lesions, a pathogen that will potentially impact tambaqui aquaculture in the future.

Transmission of Escherichia coli Causing Pyometra between Two Female Dogs.

Despite its clinical relevance, the pathogenesis of canine pyometra remains poorly understood. To date, it is recognized as a non-transmissible infectious disease. In this study, the simultaneous occurrence of pyometra and Escherichia coli in two cohabitant female dogs underwent in-depth investigation due to the hypothesis of transmission between these animals. Two 5-year-old Chow Chow dogs (namely, dogs 23 and 24-D23 and D24) were referred to a veterinary hospital with suspected pyometra. Both animals showed prostration, anorexia, and purulent vulvar discharge over a 1-week period. After ovariohysterectomy, uterine tissue, uterine contents, and rectal swabs were collected for histopathological and microbiological analysis. Uterine histology demonstrated purulent material and multifocal necrosis with endometrial ulceration, and a morphological diagnosis of pyometra was confirmed. Furthermore, E. coli from the same phylogroup (B2) and positive for the same virulence factors with the same antimicrobial susceptibility profile was isolated from the uterine contents of both dogs and the rectum of D23. Conversely, the E. coli strains recovered from D24 differed in phylogroup (one isolate), virulence factors (all three isolates), and antimicrobial susceptibility (all three isolates). Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) suggested that all isolates from the uterine content of both dogs and the rectal swab of D23 were 100% the same, but different from all isolates in the rectal swab of D24. One isolate from the uterine content of each animal as well as rectal swabs were subjected to whole-genome sequencing (WGS). Both whole-genome multilocus sequence typing(wgMLST) and single-nucleotide polymorphism (SNP) analysis supported the hypothesis that the isolates from the uterine content of both animals and the rectal swab of D23 were clonal. Taken together, these clinical features, pathology, microbiology, and molecular findings suggest, to the best of our knowledge, the first transmission of E. coli associated with pyometra between two animals. These results could impact the management of sites where several females cohabit in the same local area such as kennels.

Comparative polyphasic characterization of Weissella strains isolated from beaked whale and rainbow trout (Oncorhynchus mykiss): confirmation of Weissella ceti sp. nov. and description of the novel Weissella tructae sp. nov. isolated from farmed rainbow trout.

The weissellosis agent bacterium (WS08T = CBMAI 2730) was isolated from diseased rainbow trout (Oncorhynchus mykiss) in Brazil. The whole genome sequence of this strain was compared with the Mexican W-1 strain, also isolated from diseased rainbow trout, and with the Weissella ceti type strain CECT 7719 T (= 1119-1A-09 T = CCUG 59653 T), recovered from the beaked whale. Digital DNA-DNA hybridization pairwise analyses scored 98.7% between the Mexican W-1 and Brazilian WS08T but just 24.4% for both fish isolates compared to the W. ceti type strain CECT 7719 T. The 16S rRNA gene sequence comparisons with isolates of W. ceti, available at GenBank, were conducted. All rainbow trout-pathogenic isolates grouped close (97% bootstrap confirmation), but when this group was compared to the W. ceti type strain CECT 7719 T the similarity varied from 78.9 to 79.1%. Phenotypic assays were also conducted, and the W. ceti type strain diverged from WS08T and W-1 in the hydrolysis of aesculin, D-mannose, and potassium gluconate and in the hydrolysis of hippurate. Moreover, WS08T and W-1 showed weak growth at 5 °C whereas no growth was observed for W. ceti CECT 7719 T. The major fatty acids (> 10% total fatty acids) presented by WS08T and W-1 were summed feature 8 (C18:1 ω7c/C18:1 ω6c), summed feature 3 (C16:1 ω6c/C16:1ω7c), and C16:0. The results of phylogenetic and phenotypic analyses clearly differentiated the W. ceti CECT 7719 T type strain from the assessed pathogenic strains obtained from rainbow trout. Therefore, Weissella strains isolated from rainbow trout, here represented by strain WS08T (= CBMAI 2730), should be known as members of a novel species for which the name Weissella tructae sp. nov. is proposed.

Characterization of the virulence of three novel clade 2 Clostridioides (Clostridium) difficile strains and a two-year screening in animals and humans in Brazil.

Clostridioides (Clostridium) difficile infection (CDI) is an evolving global healthcare problem, and owing to the diverse and dynamic molecular epidemiology of C. difficile, new strains continue to emerge. In Brazil, only two cases of CDI due to the so called hypervirulent PCR ribotype (RT) 027 belonging to clade 2 have ever been reported, whereas incidence of CDI due to another "hypervirulent" RT078 (clade 5) has not yet been reported. In contrast, novel clade 2 strains have been identified in different hospitals. To better understand the epidemiology of CDIs in Brazil, this study aimed to genotypically and phenotypically characterize three novel Brazilian clade 2 strains (RT883, 884, and 885) isolated from patients with confirmed CDI. In addition, to better understand the circulating RTs, a two-year sampling was conducted in patients from the same hospital and in several domestic and wild animal species. The three strains examined showed lower production of A/B toxins than the control RT027, although two of these strains harbored a truncated tcdC gene. All strains showed swimming motility similar to that of RT027, while RT883 showed higher spore production than the reference strain. In the in vivo hamster model, the lethality of all strains was found to be similar to that of RT027. Both cgMLST and cgMLSA analyses revealed a high genetic similarity among the three-novel clade 2 isolates. In the two-year survey in animals and humans, RT883, 884, and 885 were not detected; however, three new RTs (RT988, RT989, and RT990) were isolated, two of which were genetically related to the three previously reported clade 2 strains. RT106 and RT126 were most frequently detected in humans (47.9%) and animals (57.9%), respectively. Furthermore, RT027 and RT078 were not detected in humans. The results of this study suggest that these novel clade 2 strains have virulence potential and that new strains from clade 2 continue to emerge in our setting, indicating the need for long-term local surveillance.

Occurrence and characterization of methicillin-resistant Staphylococcus spp. in diseased dogs in Brazil.

Staphylococcus pseudintermedius is a major commensal bacterium of the skin and mucosae of dogs and an opportunistic agent responsible for several clinical infections, such as pyoderma, otitis, and surgical wound infections. The emergence of methicillin-resistant S. pseudintermedius (MRSP) has become a problem of great concern in veterinary and human medicine because it is multidrug resistant (MDR) and can also infect humans. This study aimed to identify the occurrence of Staphylococcus spp. in infected patients and investigate the antimicrobial resistance profiles and molecular structure of MRSP isolates. Samples were obtained from two different veterinary clinics; suggestive colonies were submitted to matrix-assisted laser desorption ionization-time of flight (MALDI-ToF) mass spectrometry and confirmed at the species level by polymerase chain reaction (PCR). Sequencing of the 16S rRNA and rpoB genes were used in selected samples that were not identified by MALDI-ToF and by the species-specific PCR. Antimicrobial susceptibility and PCR detection of mecA were performed. MRSP isolates were subjected to multilocus sequence typing. Of all the clinical staphylococci (n = 131), 98 (74.8%) were identified as S. pseudintermedius. Multidrug resistance (resistance to ≥3 classes of antimicrobials) was observed in 63.2% of S. pseudintermedius isolates, and 24.5% of S. pseudintermedius isolates were methicillin-resistant. Half of the MRSP isolates were isolated from surgical site infections. Among the ten sequence types (ST) identified, nine were novel. ST71 was the most prevalent and associated with resistance to fluoroquinolones. Prior antimicrobial therapy, hospitalization, and surgical site infections seemed to be risk factors for MRSP acquisition. The present study showed a high rate of MDR staphylococci in infected dogs. MRSP was isolated from different clinical conditions, mainly surgical site infections. Additionally, this is the first study to extensively investigate the population structure of MRSP in Brazil, which revealed the dispersion of CC71 and nine novel ST. These findings raise concerns for both animal and human health due to the zoonotic potential of this species and limited therapeutic options available for MRSP infections.

First report of infectious spleen and kidney necrosis virus in Nile tilapia in Brazil.

In June 2020, an atypical fatal outbreak in a Brazilian Nile tilapia farm was investigated. Twenty-three animals were collected and different tissues were used for bacterial isolation, histopathological and electron microscopic examination and viral detection using molecular methods. A large number of megalocytes were observed in the histopathological analysis of several tissues. Icosahedral virions, with a diameter of approximately 160 nm, were visualized inside the megalocytes through transmission electron microscopy of the spleen tissue. The virions were confirmed to be infectious spleen and kidney necrosis virus (ISKNV) through PCR and sequencing analyses of the fish samples. Phylogenetic analysis indicated that the virus belongs to the Clade 1 of ISKNV. This viral pathogen is associated with high mortality in the early stages of cultured Nile tilapia in the United States, Thailand and Ghana; however, until now, there have been no reports from ISKNV affecting cultured fish in Brazil. Additionally, in 14 out of 23 sampled fish, Streptococcus agalactiae, Edwardsiella tarda or Aeromonas hydrophila infections were also detected. This is the first report of fatal ISKNV infections in the Brazilian Nile tilapia fish farms and represents a new challenge to the aquaculture sector in the country.

Comparative Proteomic Analyses Between Biofilm-Forming and Non-biofilm-Forming Strains of Corynebacterium pseudotuberculosis Isolated From Goats.

Caseous lymphadenitis (CLA) is a chronic disease that affects small ruminants and causes economic losses in the associated breeding system. The causative agent of CLA is Corynebacterium pseudotuberculosis, a Gram-positive bacterium that exhibits tropism for external and internal lymph nodes and induces abscess formation in the host. Bacterial communities often produce a biofilm matrix that serves various functions, including protection against hostile environmental conditions, antibiotics, and the host immune response. Although biofilm formation has been reported for C. pseudotuberculosis, not all strains demonstrate this property in culture. In this work, we report the first comparative proteomic analysis of one biofilm-forming (CAPJ4) and one biofilm-non-forming strain (CAP3W) of C. pseudotuberculosis isolated from goats. Bacterial whole cell protein extracts were obtained for mass spectrometry analyses. Using LC-MS/MS, our studies reveal three and four proteins exclusively found in the CAPJ4 and CAP3W proteome, respectively. In addition, label-free quantitative analysis identified 40 proteins showing at-least 2-fold higher values in CAPJ4 compared CAP3W proteome Notably, CAPJ4 differentially synthesized the penicillin-binding protein, which participates in the formation of peptidoglycans. CAPJ4 also exhibited upregulation of N-acetylmuramoyl-L-alanine amidase and galactose-1-phosphate uridylyltransferase, which are involved in biofilm formation and exopolysaccharide biosynthesis. Here, we demonstrate that biofilm formation in C. pseudotuberculosis is likely associated with specific proteins, some of which were previously shown to be associated with virulence and biofilm formation in other organisms. Our findings may drive studies related to the bacterial mechanisms involved in the biofilm formation, in addition to providing targets for the treatment of CLA.

Salivary and Intestinal Transcriptomes Reveal Differential Gene Expression in Starving, Fed and Trypanosoma cruzi-Infected Rhodnius neglectus.

Rhodnius neglectus is a potential vector of Trypanosoma cruzi (Tc), the causative agent of Chagas disease. The salivary glands (SGs) and intestine (INT) are actively required during blood feeding. The saliva from SGs is injected into the vertebrate host, modulating immune responses and favoring feeding for INT digestion. Tc infection significantly alters the physiology of these tissues; however, studies that assess this are still scarce. This study aimed to gain a better understanding of the global transcriptional expression of genes in SGs and INT during fasting (FA), fed (FE), and fed in the presence of Tc (FE + Tc) conditions. In FA, the expression of transcripts related to homeostasis maintenance proteins during periods of stress was predominant. Therefore, the transcript levels of Tret1-like and Hsp70Ba proteins were increased. Blood appeared to be responsible for alterations found in the FE group, as most of the expressed transcripts, such as proteases and cathepsin D, were related to digestion. In FE + Tc group, there was a decreased expression of blood processing genes for insect metabolism (e.g., Antigen-5 precursor, Pr13a, and Obp), detoxification (Sult1) in INT and acid phosphatases in SG. We also found decreased transcriptional expression of lipocalins and nitrophorins in SG and two new proteins, pacifastin and diptericin, in INT. Several transcripts of unknown proteins with investigative potential were found in both tissues. Our results also show that the presence of Tc can change the expression in both tissues for a long or short period of time. While SG homeostasis seems to be re-established on day 9, changes in INT are still evident. The findings of this study may be used for future research on parasite-vector interactions and contribute to the understanding of food physiology and post-meal/infection in triatomines.

Cell wall glycolipids from Corynebacterium pseudotuberculosis strains with different virulences differ in terms of composition and immune recognition.

Caseous lymphadenitis (CLA) is an infectious disease caused by Corynebacterium pseudotuberculosis in small ruminants and is characterized by the development of granulomas in the lymph nodes, spleen, liver, and lungs. Although little is known about the host-pathogen relationship of this bacterium, it was previously reported that the pathogen's lipids are important for its taxonomic classification and survival inside macrophages. However, there are no studies regarding the composition of these molecules. In this study, cell wall glycolipids from two C. pseudotuberculosis strains presenting different virulence profiles were purified and its composition was characterized. A difference was observed between the electrophoretic and chromatogram profiles for cell wall components from the two strains, mainly among molecules with low molecular weights. IgM from sheep with acute CLA recognized antigens with an estimated molecular weight of 11 kDa of the low-pathogenicity strain, while low-molecular weight antigens from the high-pathogenicity strain presented a lower recognition by these antibodies. Mass spectrometry analysis showed that the cell wall of the high-pathogenicity strain contained glycolipids with high amounts of unsaturated fatty acids and glycerophosphoinositols, which may contribute to the capacity of this strain to cause severe disease. In conclusion, it is indicated that cell wall non-protein antigens can play a key role in C. pseudotuberculosis virulence.

Cardiomyocyte Proteome Remodeling due to Isoproterenol-Induced Cardiac Hypertrophy during the Compensated Phase.

PURPOSE: Although the pathophysiological response of cardiac tissue to pro-hypertrophic stimulus is well characterized, a comprehensive characterization of the molecular events underlying the pathological hypertrophy in cardiomyocytes during the early compensated cardiac hypertrophy is currently lacking. EXPERIMENTAL DESIGN: A quantitative label-free proteomic analysis of cardiomyocytes isolated was conducted from mice treated subcutaneously with isoproterenol (ISO) during 7 days in comparison with cardiomyocytes from control animals (CT). RESULTS: Canonical pathway analysis of dysregulated proteins indicated that ISO-hypertrophy drives the activation of actin cytoskeleton and integrin-linked kinase (ILK) signaling, and inhibition of the sirtuin signaling. Alteration in cardiac contractile function and calcium signaling are predicted as downstream effects of ISO-hypertrophy probably due to the upregulation of key elements such as myosin-7 (MYH7). Confocal microscopy corroborated that indeed ISO-treatment led to increased abundance of MYH7. Potential early markers for cardiac hypertrophy as APBB1, GOLGA4, HOOK1, KATNA1, KIFBP, MAN2B2, and SLC16A1 are also reported. CONCLUSIONS AND CLINICAL RELEVANCE: The data consist in a complete molecular mapping of ISO-induced compensated cardiac hypertrophy model at cardiomyocyte level. Marker candidates reported may assist early diagnosis of cardiac hypertrophy and ultimately heart failure.

Re-sequencing and optical mapping reveals misassemblies and real inversions on Corynebacterium pseudotuberculosis genomes.

The number of draft genomes deposited in Genbank from the National Center for Biotechnology Information (NCBI) is higher than the complete ones. Draft genomes are assemblies that contain fragments of misassembled regions (gaps). Such draft genomes present a hindrance to the complete understanding of the biology and evolution of the organism since they lack genomic information. To overcome this problem, strategies to improve the assembly process are developed continuously. Also, the greatest challenge to the assembly progress is the presence of repetitive DNA regions. This article highlights the use of optical mapping, to detect and correct assembly errors in Corynebacterium pseudotuberculosis. We also demonstrate that choosing a reference genome should be done with caution to avoid assembly errors and loss of genetic information.

Proteomic fingerprinting for the fast and accurate identification of species in the Polyporoid and Hymenochaetoid fungi clades.

Basidiomycotan fungi play significant roles in the biogeochemical cycle of carbon as wood decomposers and are used in the food industry for mushroom production and in biotechnology for the production of diverse bioactive compounds and bioremediation. The correct identification of basidiomycotan isolates is crucial for understanding their biology and being able to expand their applications. Currently, the identification of these organisms is performed by analyzing morphological and genomic characteristics, primarily those based on DNA biomarkers. Despite their efficiency, such methods require considerable expertise and are both time-consuming and error-prone (multistep workflow). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged in the last decade as an accurate, fast, and powerful alternative for the identification of microorganisms. MALDI-TOF MS has been widely applied for the identification and taxonomical characterization of both bacteria and ascomycotan fungi from clinical origins. However, species of Basidiomycota have been poorly evaluated using this method. In the present study, we assessed the performance of MALDI-TOF MS using basidiomycotan isolates of two distinct taxonomical families: Polyporaceae and Hymenochaetaceae. Using a simple protocol, which eliminates the protein extraction step, we obtained high-quality mass spectra data and demonstrated that this method is efficient for the discrimination of isolates at the species level. SIGNIFICANCE: In this study, the MALDI-TOF mass spectrometry was employed to test its accuracy on the recognition of fungal species with high biotechnological and environmental interest. Using a simple and fast protocol, we obtained high-quality mass-spectra (protein fingerprinting) and proved that MALDI-TOF MS is sufficiently robust to the identification at species level and to evaluate the relationships among the isolates of the polyporoid and hymenochaetoid clades (Basidiomycota).

Effects of temperature changes in the transcriptional profile of the emerging fish pathogen Francisella noatunensis subsp. orientalis.

One of the major challenges in Nile tilapia (Oreochromis niloticus L.) farming is the occurrence of bacterial infections, and the Francisella noatunensis subsp. orientalis (FNO) is an important pathogen that has emerged in last decades. Francisellosis outbreaks have been reported in the literature as occurring seasonally when water temperature is below 24 °C. The aim of this study was to quantify the median lethal doses (LD50) of FNO in experimental challenges at 28 °C and 22 °C, and to investigate the impact of temperature changes in whole genome expression using microarray technology. The LD50 for Nile tilapia at 28 °C was ∼105.7, whereas at 22 °C, the LD50 was ∼102.2, showing that the decrease in temperature enhanced disease outcome. Out of 1917 genes screened, a total of 31 and 19 genes were down- and up-regulated at 22 °C, respectively. These genes were grouped by orthology into functional categories of: amino acid, inorganic ion, and carbohydrate transport and metabolism; transcription; and posttranslational modification, protein turnover, and chaperones. Expression of genes related to metabolism, oxidative stress, and thermal shock were regulated by temperature changes, reflecting an ability of FNO to adapt to the environment. Expression of virulence genes usually required for the Francisella genus was not changed between tested temperatures, including that of genes located on the Francisella Pathogenicity Island.

Molecular epidemiology of Clostridioides (previously Clostridium) difficile isolates from a university hospital in Minas Gerais, Brazil.

The molecular epidemiology of 38 non-duplicate toxigenic Clostridioides (previously Clostridium) difficile isolates from inpatients from a hospital in Brazil during a 6-year period (2012-2017) were investigated by multilocus sequence typing (MLST) and ribotyping. These isolates were classified into 20 sequence types (ST), six (30%) of which were novel, revealing a high diversity in a single hospital. Classic hypervirulent strains ST1/RT027 and ST11/RT078 were not identified, while ST42 (almost all RT106) was the most common type, being detected in 11 (28.9%) strains. Noteworthy, six (15.8%) isolates were classified into five STs from clade 2, four of which were new ST and RT. Our study suggests that possible hypervirulent strains other than ST1/RT027 might be inadvertently circulating in Brazilian hospitals and highlights the importance of permanent surveillance on circulating strains in a national scale.

Delineation of the pan-proteome of fish-pathogenic Streptococcus agalactiae strains using a label-free shotgun approach.

BACKGROUND: Streptococcus agalactiae (GBS) is a major pathogen of Nile tilapia, a global commodity of the aquaculture sector. The aims of this study were to evaluate protein expression in the main genotypes of GBS isolated from diseased fishes in Brazil using a label-free shotgun nano-liquid chromatography-ultra definition mass spectrometry (nanoLC-UDMSE) approach and to compare the differential abundance of proteins identified in strains isolated from GBS-infected fishes and humans. RESULTS: A total of 1070 protein clusters were identified by nanoLC-UDMSE in 5 fish-adapted GBS strains belonging to sequence types ST-260 and ST-927 and the non-typeable (NT) lineage and 1 human GBS strain (ST-23). A total of 1065 protein clusters corresponded to the pan-proteome of fish-adapted GBS strains; 989 of these were identified in all fish-adapted GBS strains (core proteome), and 62 were shared by at least two strains (accessory proteome). Proteins involved in the stress response and in the regulation of gene expression, metabolism and virulence were detected, reflecting the adaptive ability of fish-adapted GBS strains in response to stressor factors that affect bacterial survival in the aquatic environment and bacterial survival and multiplication inside the host cell. Measurement of protein abundance among different hosts showed that 5 and 26 proteins were exclusively found in the human- and fish-adapted GBS strains, respectively; the proteins exclusively identified in fish isolates were mainly related to virulence factors. Furthermore, 215 and 269 proteins were up- and down-regulated, respectively, in the fish-adapted GBS strains in comparison to the human isolate. CONCLUSIONS: Our study showed that the core proteome of fish-adapted GBS strains is conserved and demonstrated high similarity of the proteins expressed by fish-adapted strains to the proteome of the human GBS strain. This high degree of proteome conservation of different STs suggests that, a monovalent vaccine may be effective against these variants.

Rapidly evolving changes and gene loss associated with host switching in Corynebacterium pseudotuberculosis.

Phylogenomics and genome scale positive selection analyses were performed on 29 Corynebacterium pseudotuberculosis genomes that were isolated from different hosts, including representatives of the Ovis and Equi biovars. A total of 27 genes were identified as undergoing adaptive changes. An analysis of the clades within this species and these biovars, the genes specific to each branch, and the genes responding to selective pressure show clear differences, indicating that adaptation and specialization is occurring in different clades. These changes are often correlated with the isolation host but could indicate responses to some undetermined factor in the respective niches. The fact that some of these more-rapidly evolving genes have homology to known virulence factors, antimicrobial resistance genes and drug targets shows that this type of analysis could be used to identify novel targets, and that these could be used as a way to control this pathogen.

Complete genome sequencing of sixteen Francisella noatunensis subsp. orientalis isolates: A genomic approach for molecular characterization and spread dynamics of this clonal population.

Francisella noatunensis subsp. orientalis (FNO) is an important emerging pathogen associated with disease outbreaks in farm-raised Nile tilapia. FNO genetic diversity using PCR-based typing, no intra-species discrimination was achieved among isolates/strains from different countries, thus demonstrating a clonal behaviour pattern. In this study, we aimed to evaluate the population structure of FNO isolates by comparing whole-genome sequencing data. The analysis of recombination showed that Brazilian isolates group formed a clonal population; whereas other lineages are also supported by this analysis for isolates from foreign countries. The whole-genome multilocus sequence typing (wgMLST) analysis showed varying numbers of dissimilar alleles, suggesting that the Brazilian clonal population are in expansion. Each Brazilian isolate could be identified as a single node by high-resolution gene-by-gene approach, presenting slight genetic differences associated to mutational events. The common ancestry node suggests a single entry into the country before 2012, and the rapid dissemination of this infectious agent may be linked to market sales of infected fingerlings.