SEARCH · Search PubMed

Results for “Virulence profiling”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources

PubMed1987

Canine distemper virus: in vivo virulence of in vitro-passaged persistent virus strains.

Groups of ferrets were inoculated intraperitoneally with cell lysates or equivalent doses of whole cells from 9 different cell lines persistently infected with canine distemper virus. Viral persistence in these cell lines was characterized by noncytolytic infection and restricted release of cell-free infectious virus. In vivo replication competency of the various viruses in ferrets ranged from nil to virulent and did not correlate with in vitro titers of inocula. Ferret virulence (cell lysates only) for one cell line (CCL64-RCDV) was associated with morphologic absence of virion assembly, failure to interfere with lytic virus replication after superinfection, and in vitro infectivity restricted to canine macrophage-like tumor cells. Virion protein production in the CCL64-RCDV virulent inoculum and in the CCL64-Ly avirulent inoculum was evaluated by use of the immunoblot technique. All major virion proteins were produced by infected cells. Virulence was not associated with obvious changes in electrophoretic mobility of virion proteins when profiles of ferret-virulent CCL64-RCDV were compared with those of avirulent CCL64-Ly.

Animals↗

PubMed1997

Expression profile and subcellular location of the plasmid-encoded virulence (Spv) proteins in wild-type Salmonella dublin.

The plasmid-encoded virulence genes (spvABCD) in nontyphoid Salmonella strains mediate lethal infections in a variety of animals. Previous studies have shown that these genes are transcriptionally regulated by stationary-phase growth. We studied the expression profile and the subcellular locations of the SpvABCD proteins in wild-type S. dublin by using polyclonal antibodies against SpvA, SpvB, SpvC, and SpvD. The cellular levels of the individual proteins were determined during growth by quantitative immunoblotting. As expected, SpvA, SpvB, SpvC, and SpvD were not detectable before the late logarithmic growth phase and appeared in the sequence SpvA, SpvB, SpvC, and SpvD. In contrast to the transcriptional regulation, however, SpvA and SpvB reached their maximal expression shortly after induction and declined during further growth whereas SpvC and SpvD expression remained high throughout the stationary phase, indicating that the Spv proteins are individually regulated at a posttranscriptional level. To localize SpvABCD within the bacteria, the cells were fractionated into the periplasmic, cytoplasmic, inner membrane, and outer membrane components. The cell fractions and the culture supernatant were analyzed by immunoblotting. SpvA was present in the outer membrane, SpvB was present in the cytoplasm and the inner membrane, and SpvC was present in the cytoplasm. SpvD was secreted into the supernatant; however, a substantial portion of this protein was also detected in the cytoplasm and membranes. The molecular weights of SpvD in the supernatant and in the cytoplasm appeared to be equal, suggesting that SpvD is not cleaved upon secretion.

Bacterial Proteins↗

PubMed2006

Tools to study molecular mechanisms of Aspergillus pathogenicity.

The unique nature of Aspergillus fungi represents a challenge for scrutinizing the attributes that render these saprophytic microorganisms pathogenic or allergenic under certain environmental circumstances. Recent publication of the genomic sequence from an isolate of the major pathogen Aspergillus fumigatus denotes enormous progress in aiming at cellular features and gene products that contribute to its pathogenicity. Latest developments to study virulence-related characteristics comprise profiling techniques, conditional gene inactivation and precise manipulation of the genome by means of gene targeting. Advances in assessing the virulence potential of particular mutant strains in alternative test systems complement these approaches.

Animals↗

PubMed2004

Molecular characterization of Salmonella enterica subsp. enterica serovar Typhimurium DT1 isolates.

Salmonella Typhimurium DT1 is endemic to Finland and has caused human outbreaks since the 1960s. Domestic DT1 isolates (n=235) from 1972 to 1999 from human cases, animals and other sources, as well as foreign DT1 isolates from human cases (n=20) were analysed by molecular methods. Pulsed-field gel electrophoresis (PFGE) yielded 38 XbaI profiles. Of these, XbaI profile 10 was seen in 49% (125/255) of the isolates. Twelve IS200 profiles were obtained; the most common IS200 profile D was seen in 64% (33/52) of the isolates. Two clusters were formed by compilation of the XhaI-, BlnI- and SpeI-PFGE and IS200 profiles and possession of the serovar-specific virulence plasmid. The major cluster contained eight IS200 profiles, including IS200 profile D and XhaI profile 10, and had no virulence plasmid, and can be regarded as typical of the endemic Typhimurium DT1 infection.

DNA Transposable Elements↗

PubMedDate not supplied

Characterization of Egyptian field strains of infectious bursal disease virus.

The reverse transcriptase-polymerase chain reaction/restriction fragment length polymorphism (RT-PCR/RFLP) technique was used for identification and characterization of Egyptian field strains of infectious bursal disease viruses (IBDVs) that caused severe outbreaks with (30%-60%) mortality rate. Twenty-four bursal samples collected from 24 field outbreaks in commercially reared chicken flocks experiencing signs typical of infectious bursal disease (IBD) were used. Ten of the bursal samples examined were determined to contain IBDV as evidenced by amplification of a 743-bp region of the VP2 gene of IBDV by RT-PCR. The RT-PCR products of the detected viruses were characterized by digestion with three restriction enzymes, BstN, MboI, and SpI. Three different RT-PCR/RFLP profiles were observed. Seven of the detected viruses had RFLP profiles identical to the very virulent European strains of IBDV (vvIBDVs). One virus had a RFLP profile identical to the U.S. classic vaccine strain, and one virus had a unique RFLP profile. The clinical history of the outbreaks and the presence of the SspI site in the 743-bp RT-PCR fragment were the criteria for designating the viruses as belonging to the very virulent (vv) phenotype.

Base Sequence↗

PubMed2002

Biological and molecular characterization of a raccoon isolate of Trypanosoma cruzi from South Carolina.

Biological and molecular characteristics of a raccoon isolate of Trypanosoma cruzi (R36) were compared with those of a known virulent strain (Brazil). Included in the characterization were growth rate in liver infusion tryptose medium, infectivity for murine fibroblasts, intracellular amastigote replication and trypomastigote release rates, polymerase chain reaction (PCR) profiling of the mini-exon gene, isoenzyme and random amplified polymorphic DNA (RAPD) profiles, and in vivo virulence for C3H/HeJ mice. Similar growth curves were noted for both strains; however, infectivity and rates of intracellular amastigote replication and trypomastigote release were significantly lower for the R36 isolate than for the Brazil strain. To determine virulence, C3H/ HeJ mice were exposed intraperitoneally to the R36 isolate. No parasite was observed in blood by direct examination or in tissues by histology; however, T. cruzi was detected by PCR in tissues (quadriceps and spleen) at 21 days postinfection. Analyses of the mini-exon gene, isoenzyme, and RAPD profiles indicate that R36 is in the T. cruzi II group and the Brazil strain is in the T. cruzi I group. Although infectivity and virulence of the raccoon isolate were lower than those for the Brazil strain, autochthonous infections in the United States have been reported, which suggests the need for further study of local T. cruzi isolates.

Animals↗

PubMed2026

Serotypic and Genomic Diversity of Vibrio anguillarum in Rainbow Trout Farms in Turkey: Implications for Vibriosis Control and Vaccine Candidate Selection.

Outbreaks of vibriosis caused by Vibrio anguillarum are a persistent constraint on rainbow trout (Oncorhynchus mykiss) aquaculture. However, information on the population structure of field strains in Turkey has been lacking. Here, we report the first systematic serotypic, proteomic, and genomic characterization of 23 V. anguillarum isolates collected over 10 years from rainbow trout farms located in six major aquaculture regions of Turkey. Serological analyses based on microagglutination, supported by ELISA characterization of hyperimmune sera, identified a clear predominance of serotype O1, whereas isolate V12 exhibited a non-agglutinating, atypical O-antigen profile. Protein profiling (SDS-PAGE) and immunoblotting showed largely conserved whole-cell protein patterns among the isolates, but distinct immunogenic bands at 14, 18, and 40 kDa were detected in isolates V18 and V21. Long-read whole-genome sequencing revealed that most Turkish isolates grouped within the global O1 clade, while V12, V25, and V28 isolates occupied more distant branches. Comparative genomics demonstrated a conserved core virulence gene set (RTX toxins, siderophore and iron-uptake systems, motility and adhesion factors, Type VI secretion system), with strain-dependent variation in accessory loci such as anguibactin and T6SS-I. Experimental infections of rainbow trout demonstrated significant differences in virulence among isolates (p < 0.05), with the V18 isolate showing high, the V15 intermediate, and the V12 low-mortality rates. By elucidating the relationship among the serotype, immunogenic protein profiles, virulence gene repertoires, and in vivo pathogenicity, this study provides a comprehensive overview of the antigenic and genomic diversity of Vibrio anguillarum isolates from Turkey. Notably, the identification of V18 and V21 as promising candidate strains for further vaccine evaluation, characterized by high virulence and unique immunogenic features, provides a scientific foundation for the development of serotype-specific vaccination strategies to mitigate vibriosis-associated losses in aquaculture.

Animals↗

PubMed2003

55 kb plasmid and virulence-associated genes are positively correlated with Salmonella enteritidis pathogenicity in mice and chickens.

Twenty-four strains of Salmonella enteritidis, isolated from several outbreaks of salmonellosis from different poultry farms in India, were checked for the plasmid profile and detection of virulence gene(s) by PCR. Most of the strains contained only a single plasmid of 55 kb. Additional plasmids of 23.2 kb and 8.7 kb were seen in one of the strains, and another strain carried only two plasmids of 23.2 kb and 8.7 kb. Four strains did not carry any plasmid. PCR amplification showed the presence of virulence-associated genes in all the isolates harbouring the 55 kb plasmid. Intraperitoneal inoculation of mice, with most of the strains carrying the 55 kb plasmid, caused 100% mortality. Most strains lacking the 55 kb plasmid were avirulent. In chickens, oral inoculation of the S. enteritidis strains carrying the 55 kb plasmid produced 40-100% mortality, with characteristic signs of salmonellosis. Oral inoculation of strains lacking the 55 kb plasmid did not cause any mortality. Hence, it appears that the large plasmid of S. enteritidis probably contributes towards virulence in mice and chickens.

Animals↗

PubMed2026

Integrated functional genomics and safety assessment of plant-growth-promoting Caryophanales from post-maize-cultivation soils.

This study aimed to evaluate six environmental bacterial strains isolated from post-maize cultivation soils as candidates for agricultural biopreparation development, using an integrated functional genomic and safety assessment framework. Building on experimental validation of plant-growth-promoting activities, the analysis included: plant-growth-promoting traits (PGPT-Pred) using PLABase; carbohydrate-active enzymes (CAZymes) relevant for lignocellulosic crop residue degradation (dbCAN3); secondary metabolite profiles (antiSMASH); and screening for virulence factors and antibiotic resistance genes (ABRicate, BTyper3).All analyzed strains possess 1,449-1,617 predicted PGPT-encoding genes (24.1-35.9% of total genes), which are strongly shaped by taxonomic relatedness, as confirmed by congruence testing against ANI-based genomic divergence. Paenibacillus amylolyticus 5mez and Priestia megaterium 7psych showed distinct functional profiles compared to Bacillus spp., while Bacillus subtilis sensu lato strains were most similar to each other. Genomic predictions suggest involvement in nutrient acquisition (N, P, K, Fe) and stress mitigation. Secondary metabolite analysis revealed high biosynthetic potential, with non-Bacillus species harbouring a large proportion of unknown gene clusters, indicating underexplored metabolite diversity. CAZyme profiling identified P. amylolyticus 5mez as the most enzyme-rich strain, while B. cereus s.s. zielonkawy showed ligninolytic potential despite low overall CAZyme abundance. The safety assessment identified B. cereus s.s. zielonkawy as toxigenic and unsuitable for use. Of the remaining strains, P. amylolyticus 5mez and Pr. megaterium 7psych demonstrated the most favourable safety profiles, exhibiting no detectable virulence factors or antibiotic resistance genes, justifying their priority use in agricultural biopreparations, pending phenotypic validation. Given the high-dimensional, low-sample-size nature of multi-trait datasets in applied microbial genomics, tailored statistical approaches, including noise-reduction-validated PCA and distance-based congruence testing, were applied; their rationale and limitations are discussed.

Soil Microbiology↗

PubMed1998

Reduced virulence of group A streptococcal Tn916 mutants that do not produce streptolysin S.

Streptolysin S (SLS) is a potent cytolytic toxin produced by nearly all group A streptococci (GAS). SLS-deficient Tn916 insertional mutants were generated from two clinical isolates of GAS, MGAS166s and T18Ps (M serotypes 1 and 18, respectively), by transposon mutagenesis using Tn916 donor strain Enterococcus faecalis CG110. Representative nonhemolytic transconjugants SBNH5 and SB30-2 each harbored a single Tn916 insertion in identical loci. The insertion in SBNH5 was located in the promoter region of an open reading frame, designated sagA, rendering it transcriptionally inactive. Protease, streptolysin O, and DNase activities and the production of M protein remained the same in the nonhemolytic mutants and the wild-type strains, as did the growth rates and exoprotein profiles. Transconjugants were evaluated in an established murine model by injecting the organisms subcutaneously and monitoring the mice for alterations in weight and the development of necrotic lesions. Animals infected with SBNH5, compared to those infected with MGAS166s, gained weight during the first 24 h (+1.15 versus -1.16 g; P < 0.05) and had fewer necrotic lesions (0 versus 7; P = 0.0007). Animals infected with SB30-2, compared to those infected with T18Ps, also gained weight within the first 24 h (+0.54 versus -0.66 g; P < 0.05) and produced fewer necrotic lesions (1 versus 8; P = 0.001). Revertants of the mutants in which Tn916 had been excised regained the hemolytic phenotype and the virulence profile of the wild-type strains. This study demonstrates that SLS-deficient mutants of GAS, belonging to different M serotypes and containing identical Tn916 mutations, are markedly less virulent than their isogenic parents.

Amino Acid Sequence↗

PubMed2005

Transcript profiles of Blumeria graminis development during infection reveal a cluster of genes that are potential virulence determinants.

High-density cDNA microarrays (2,027 unigenes) were used to analyze transcript profiles of the plant-pathogenic fungus Blumeria graminis f. sp. hordei throughout its asexual life cycle and development of infection. RNA was obtained from four stages preceding penetration and four stages after penetration of the host cells. The microarray data was validated by comparing the expression of a plasma membrane H+-ATPase and fructose-1,6-bis phosphatase with the data obtained from a quantitative polymerase chain reaction (PCR) assay. The results showed that there was a global switch in expression between the pre- and postpenetrative stages. This was largely due to accumulation of RNA encoding protein biosynthesis genes in the late stages. Other functional clusters, such as virulence-related genes and sterol metabolism genes, are up-regulated in pre- and postpenetration stages, respectively. A group of RNAs whose abundance correlated with the expression of cap20, a gene known to be required for virulence in Colletotrichum gloeosporioides, identified genes that are strong candidates for pathogenicity factors in B. graminis.

Ascomycota↗

PubMed1994

Increase of capsular material thickness following in vivo growth of virulent Streptococcus suis serotype 2 strains.

Protein profile and capsular material thickness of Streptococcus suis serotype 2 strains were compared after in vitro and in vivo growth. Three virulent and one avirulent strains were used. These strains were grown in Brain Heart Infusion (BHI) broth, cells were collected by centrifugation, resuspended in a sterile saline solution and injected in diffusion chambers. The devices were then inserted in rat abdomens for 17 h. In vitro grown strains were also inoculated into fresh BHI broth and cultivated for 17 h at 37 degrees C. In vivo as well as in vitro grown bacteria were harvested by centrifugation, processed in a French pressure cell, treated with lysozyme and centrifuged to collect cell proteins for SDS-PAGE analysis. Transmission electron microscopy using polycationic ferritin labeling to stabilize capsular material was also carried out. No significant modification was noted in the protein profile for any strain after in vivo growth except for a 39 kDa protein of one virulent strain. On the other hand, an increase in thickness of capsular material was noted for the three in vivo grown virulent strains while no change was noted for the avirulent strain. This increase in capsular material thickness of virulent strains was accompanied by an increased resistance to killing by pig polymorphonuclear leukocytes. The capacity to produce more capsular material in vivo seems to be an attribute of some virulent S. suis serotype 2 strains.

Animals↗

PubMed2005

sigmaB activity in a Staphylococcus aureus hemB mutant.

Inactivation of hemB in Staphylococcus aureus strain Newman resulted in a small-colony phenotype and was accompanied by an altered expression pattern of global regulators and control of virulence factor production. Transcription profiles followed over 15 h by Northern blot analyses revealed that transcripts of the global regulators arl, rot, sae, sarR, sarS, srr, svrA, and sigB disappeared after the exponential phase and that both agr transcripts were completely absent in the hemB mutant. Apart from a general concentration of transcriptional activity to the exponential phase, premature gene expression was observed for rot, hla, and spa. Nevertheless, reported sigmaB-dependent transcripts, such as sarC and clfA, were produced throughout the 15-h growth period monitored. The absence of these transcripts in a hemB sigB double mutant demonstrated their dependence on sigmaB and indicated an unexpected, permanent sigmaB activity in the hemB mutant. Variations in the extents of the directly sigmaB-controlled asp23, rsbVW-sigB, and sarC transcripts argue for additional factors modulating sigmaB activity. This study provides the first extended synopsis of the transcriptional patterns of different regulators over the entire growth cycle in the widely used Newman strain.

Bacterial Proteins↗

PubMed2005

Virulence and molecular diversity in Colletotrichum graminicola from Brazil.

Genetic diversity among 37 isolates of the sorghum anthracnose pathogen Colletotrichum graminicola, from four geographically distinct regions of Brazil, was evaluated by RAPD and RFLP-PCR markers and virulence characters on a set of 10 differential sorghum genotypes. Twenty-two races were identified and race 13B was the most frequent, but present in only two regions. RAPD analysis revealed 143 polymorphic bands that grouped the isolates according to their geographic origin, but not by their virulence phenotypes. RFLP with HaeIII, MspI, HinfI, HhaI, HpaII, EcoRI, HindIII, PstI, RsaI, Taq alphaI, and AluI enzymes over ITS domains and 5.8 rDNA genes of C. graminicola did not show differences among the isolates, indicating high conservation of these restriction sites. Molecular polymorphism was observed among isolates belonging to the same race. No association between virulence phenotypes and molecular profiles was observed.

Brazil↗

PubMed1997

The Xanthomonas campestris gumD gene required for synthesis of xanthan gum is involved in normal pigmentation and virulence in causing black rot.

A cloned 4.1-kb EcoRI fragment from Xanthomonas campestris pv. campestris was previously shown to complement the non-mucoid mutant P22 and increase xanthan gum production after being transformed into the wild-type strain Xc17. The gene responsible for these effects was identified, sequenced, and shown to be the gumD gene which has previously been proposed to encode glucose transferase activity, an enzyme required for adding the first glucose residue to the isoprenoid glycosyl carrier lipid during xanthan synthesis. A gumD mutant, isolated from Xc17 by gene replacement, was shown to possess altered pigment xanthomonadin profiles and exhibit reduced virulence in causing black rot in broccoli. This study appears to be the first to demonstrate that interruption of a gene required for xanthan synthesis can lead to reduced virulence of X. campestris.

Bacterial Proteins↗

PubMed2006

Detection of virulence determinants in clinical strains of Salmonella enterica serovar Enteritidis and mapping on macrorestriction profiles.

A total of 80 strains of Salmonella enterica serovar Enteritidis, causing gastroenteritis (G) or bacteraemia (B), and three control strains (C), were subjected to: (i) detection of 14 chromosomally and 1 plasmid-located virulence genes by PCR, (ii) detection of DNA polymorphisms by XbaI and BlnI PFGE, and cluster analysis, (iii) mapping of the 15 screened sequences on macrorestriction profiles and (iv) comparison of the screening and mapping results with data available for other Salmonella strains. Identical virulence genotypes and very similar macrorestriction profiles were shown by most S. Enteritidis strains. However, a number of B strains belonged to genomic types with polymorphisms affecting fragments carrying (SPI2-slyA), (SPI2-slyA-phoP/Q-agfA), (SPI4 and/or stn) and spvC. The information obtained provides the basis for further studies on the genetic background of virulence and the molecular epidemiology of S. Enteritidis.

Chromosome Mapping↗

PubMed1987

Relationship between lipopolysaccharide composition and virulence of Haemophilus ducreyi.

The relationship between lipopolysaccharide (LPS) composition and virulence of Haemophilus ducreyi strains was investigated. Glycoses identified in LPS by gas-liquid chromatography were glucose, galactose, and their amino derivatives glucosamine and galactosamine. Fucose was found in trace amounts but mannose and rhamnose, characteristic of the O-side chain of LPS in many species, were not detected. Qualitatively, the LPS composition of the eight strains examined was similar and differences were mainly quantitative. The total glycose:KDO ratio of the LPS of virulent strains exceeded that of avirulent strains. All strains had similar fatty-acid composition but lacked lauric acid. SDS-polyacrylamide gel electrophoresis of the LPS of virulent and avirulent strains also revealed differences in their electrophoretic mobilities. The LPS profiles of avirulent strains were similar, but differed from those of virulent strains. These profiles lacked high mol. wt bands representing O-side chain repeating units. Thus, differences in the electrophoretic mobilities of the LPS of virulent and avirulent strains may reflect differences in the amount of carbohydrates associated with the core polysaccharide.

Electrophoresis, Polyacrylamide Gel↗

PubMed1999

Candida albicans pathogenicity: a proteomic perspective.

Candida albicans is an opportunistic fungus which causes both superficial infections and life-threatening systemic candidiasis in immunocompromised hosts such as AIDS patients, people with cancer, or other immunosuppressed individuals. Virulence factors for this fungus include the ability to adhere to host tissues, production of tissue damaging secreted enzymes, and changes in morphological form that may enhance tissue penetration and avoidance of immune surveillance. Treatment of candidiasis patients is hampered by a limited choice of antifungal agents and the appearance of clinical isolates resistant to azole drugs. Proteome analysis involves the separation and isolation of proteins by two-dimensional gel electrophoresis and their identification and characterization by mass spectrometry. The systematic application of this methodology to C. albicans is in its infancy, but is progressing rapidly. Comparing protein profiles between avirulent and virulent C. albicans strains, between drug-sensitive and -resistant strains, or between different morphological forms, could identify key control and effector proteins. There are difficulties, however, associated with the display of low abundance and cell envelope-associated proteins and the choice of conditions for obtaining suitable C. albicans cells. This article describes the potential of applying proteome analysis to C. albicans in order to better understand pathogenicity and identify new antifungal targets.

Candida albicans↗