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PubMed2006

Differences of gene expression in bovine alveolar macrophages infected with virulent and attenuated isogenic strains of Mycobacterium bovis.

Infection with Mycobacterium bovis is a significant human and animal health problem in many parts of the world. The first stage of pulmonary tuberculosis occurs after inhalation of the bacilli into an alveolus where they are ingested by resident macrophages. DNA microarray analysis was used to detect genes expressed in bovine lung alveolar macrophages infected with two isogenic strains of M. bovis, a virulent strain, ATCC35723 and an attenuated strain, WAg520 derived from ATCC35723. Chemokines, interleukin-8 and monocyte chemotactic protein 1, were more strongly expressed in ATCC35723-infected macrophages compared to WAg520-infected macrophages. Conversely, a group of genes, including fibrinogen-like protein 2 and legumain, were expressed at a higher level in macrophages infected with WAg520 compared to ATCC35723. Quantitative real-time PCR of a selected group of these differentially expressed genes confirmed enhanced levels of IL-8 mRNA in ATCC35723-infected macrophages compared to WAg520-infected macrophages. Microarray analysis of gene expression in macrophages infected with attenuated isogenic strains of M. bovis may identify key genes involved in early and protective immune responses to tuberculosis.

Animals↗
PubMedDate not supplied

Effects of chemically or virus-induced immunodepression on response of chickens to avian leukosis virus.

The effects of chemically or virus-induced immunodepression on the infection profile (development of viremia and antibody) and shedding of avian leukosis virus (ALV) were studied in progeny chickens of experimental or commercial breeder flocks. Chickens were infected with ALV subgroup A by contact at hatching and by oral inoculation at 4-5 weeks of age. In the first experiment, chickens were inoculated with a virulent strain of infectious bursal disease virus (IBDV) at 1 day or 6 weeks of age. In the second experiment, chickens were neonatally treated with cyclophosphamide (CY), or were inoculated with strain T of reticuloendotheliosis virus (REV) at hatching, or were inoculated with strain JM of Marek's disease virus (MDV) at 2 weeks of age. The infection profile and cloacal shedding of ALV in chickens exposed to ALV and inoculated with immunodepressive viruses or CY were compared with those in hatchmates exposed only to ALV. In two of four chicken lines tested in the first experiment, shedding of ALV, as determined by virological assays of cloacal swabs at 22 weeks of age, was significantly higher in chickens infected with IBDV at 1 day of age than in uninfected hatchmates. The rate of shedding of ALV in one of these two lines was also significantly higher in chickens infected with IBDV at 6 weeks of age than in uninfected chickens. Further, the frequency of ALV-antibody detection at 22 weeks of age was significantly lower in chickens of these two lines infected with IBDV at 1 day of age than in uninfected chickens. In the second experiment, neonatal treatment with CY significantly increased the frequency of viremic chickens of both experimental and commercial flocks. The frequency of ALV-viremic chickens at 22 weeks of age was considerably higher in the REV- and MDV-inoculated groups (54% and 44%, respectively) than in control hatchmates (29%), but only in chickens of the commercial line. These findings suggest that chemically or virus-induced immunodepression may lead to an increase in rates of viremia and shedding of ALV in chickens infected with virus after hatching, especially in certain genetic lines.

Animals↗
PubMed2004

Trypanosoma evansi in inbred and Swiss-Webster mice: distinct aspects of pathogenesis.

Trypanosoma evansi (Trypanosomatidae, Kinetoplastida) is a salivarian trypanosomatid that infects eight mammal orders spread over America, Europe and Asia. In Brazil, T. evansi is the etiological agent of "Mal de Cadeiras", a horse disease very often described in the region known as Pantanal do Mato Grosso. Few data concerning the genetic diversity and biology of subpopulations of T. evansi that circulate in Brazil are available. The factors that modulate the interaction of this parasite with its hosts also remain to be elucidated. Here we evaluated the course of experimental infection of six T. evansi isolates derived from domestic and wild animals in Swiss-Webster mice and three Mus musculus lineages. The follow-up included biological, immunological as well as biochemical and hematological parameters. The same isolates as well as three others were characterized by pulsed-field electrophoresis. Our results showed that T. evansi isolates displayed significant differences regarding behavior and morbidity patterns in the distinct mouse lineages. Nevertheless, these differences could not be correlated with pulsed-field electrophoresis profiles. Indeed, concerning this molecular marker, only microheterogeneity was observed. Moreover, we observed that the outcome of the infection is defined by both host genetic background and peculiarities (virulence factors) of the distinct T. evansi isolates. Anemia and hypoglycemia were the only features that could be observed in all mouse lineages, independently of the inoculated T. evansi subpopulation. In addition, our data also show that Mus musculus is a suitable model host for the study of the different pathogenetic features of T. evansi infection.

Animals↗
PubMed2005

Ability to differentiate between cp and ncp BVDV by microarrays: towards an application in clinical veterinary medicine?

Microarray expression profiling provides a comprehensive portrait of the transcriptional world enabling us to view the organism as a 'system' that is more than the sum of its parts. The vigilance of cells to environmental change, the alacrity of the transcriptional response, the short half-life of cellular mRNA and the genome-scale nature of the investigation collectively explain the power of this method. These same features pose the most significant experimental design and execution issues which, unless surmounted, predictably generate a distorted image of the transcriptome. Conversely, the expression profile of a properly conceived and conducted microarray experiment can be used for hypothesis testing: disclosure of the metabolic and biosynthetic pathways that underlie adaptation of the organism to infectious processes; the identification of co-ordinately regulated genes; the regulatory circuits and signal transduction systems that mediate the adaptive response; and temporal features of developmental programmes. The study of viral pathogenesis by microarray expression profiling poses special challenges and opportunities. Although the technical hurdles are many, obtaining expression profiles of an organism growing in tissue will probably reveal strategies for growth and survival of the virus in the host's cells. Here, we show data obtained using a tailored microarray system based on synthetic polynucleotides derived from human sequences (SIRS-Lab GmbH, Jena, Germany) to study the effect of cytopathogenic (cpe) and non-cytopathogenic (ncp) bovine viral diarrhoea virus (BVDV) infection of bovine macrophages, focusing on intracellular signalling molecules. Of the 575 genes present on the array, more than 70% showed a reaction with the oligonuleotides spotted on the array, and 26 genes were differentially expressed comparing cDNA derived from cpe and ncp infected cells. These data will help to further understand our knowledge regarding BVDV infection, and will especially help to understand differences in cellular responses to cpe and ncp biotypes.

Animals↗
PubMed2005

The coexistence of symbiosis and pathogenicity-determining genes in Rhizobium rhizogenes strains enables them to induce nodules and tumors or hairy roots in plants.

Bacteria belonging to the family Rhizobiaceae may establish beneficial or harmful relationships with plants. The legume endosymbionts contain nod and nif genes responsible for nodule formation and nitrogen fixation, respectively, whereas the pathogenic strains carry vir genes responsible for the formation of tumors or hairy roots. The symbiotic and pathogenic strains currently belong to different species of the genus Rhizobium and, until now, no strains able to establish symbiosis with legumes and also to induce tumors or hairy roots in plants have been reported. Here, we report for the first time the occurrence of two rhizobial strains (163C and ATCC11325T) belonging to Rhizobium rhizogenes able to induce hairy roots or tumors in plants and also to nodulate Phaseolus vulgaris under natural environmental conditions. Symbiotic plasmids (pSym) containing nod and nif genes and pTi- or pRi-type plasmids containing vir genes were found in these strains. The nodD and nifH genes of the strains from this study are phylogenetically related to those of Sinorhizobium strains nodulating P. vulgaris. The virA and virB4 genes from strain 163C are phylogenetically related to those of R. tumefaciens C58, whereas the same genes from strain ATCC 11325T are related to those of hairy root-inducing strains. These findings may be of high relevance for the better understanding of plant-microbe interactions and knowledge of rhizobial phylogenetic history.

Bacterial Proteins↗
PubMed2002

Genetic determinants of coxsackievirus B3 pathogenesis.

The development of high throughput genomic and bioinformatic analysis tools, coupled with established molecular techniques, has allowed new insights into the pathogenesis of infectious diseases. In humans, coxasackievirus B3 (CVB3) is the primary etiological agent of viral myocarditis, an inflammatory disease process involving the heart muscle. Early host cellular survival and apoptotic mechanisms during viral infections, as well as immune events, affect myocarditis progression and outcome. Therefore, our laboratory has been keenly interested in infectomics, defined here as the transcriptional events of both virus and host. We first elucidated up- or downregulated transcriptional activities in CVB3-infected hearts by mRNA differential display. Further characterization of these regulated genes including Nip21, IP10, and IGTPase, and study of their role in CVB3-infection are underway. In further dissection of the stages of myocarditis-peak viremia, inflammatory infiltration and tissue repair-we used cDNA microarrays to probe differential gene expression in the myocardium following virus infection. Following virus infection, there are global decreases in metabolic and mitochondrial genes, increases in signaling genes and distinctive patterns in other functional groups. To establish early gene expression profiles in infected cells by themselves, we also used oligonucleotide arrays in an in vitro model of CVB3 infection. Notably, we have found increased expression of transcription factors c-fos and c-jun down-stream of extracellular signal-related kinase, a pathway which is crucial for virus replication and pathogenesis. Our investigations based on gene profiling following CVB3 infection have thus far been fruitful in providing new experimental leads. High throughput genetic analysis has allowed us to simultaneously try on greater than 12,000 potential genetic "glass slippers." Our in vitro experimental plan has enabled us to chart prominent patterns of gene expression, analyzed by novel bioinformatic approaches, and to separate varied and potentially significant gene expression events.

Computational Biology↗
PubMed2026

Comparative genomics reveals lineage-associated structural variation and diversification in a barley fungal pathogen.

Leaf rust, caused by Puccinia hordei, is a major barley disease worldwide. Despite repeated shifts in virulence, contrasting reproductive histories, and emerging fungicide insensitivity, the genomic basis of its diversification and adaptation remains poorly understood. In this study, we generated haplotype-resolved, chromosome-level genome assemblies for two isolates with contrasting virulence and analyzed 41 Australian isolates collected over 54 yr (1966-2020), integrating comparative and population genomics, mating-type gene phylogenies, chromosome-specific k-mer profiling, genome-wide copy-number variation (CNV) analysis, and gene-expression analysis. We identified a structurally dynamic chromosome characterized by repeat-associated rearrangements, structural variation, and lineage-associated CNV, representing the first evidence in a rust fungus of chromosome-scale structural diversification of this extent. Population analyses distinguished clonally expanded lineages from recombination-associated lineages, with mating-type gene phylogenies providing further support for lineage differentiation. More recently collected isolates showed increased duplication-associated variation, and CNV boundaries were associated with structural-variant breakpoints. We also identified lineage-associated amplification of Cyp51, with increased copy number associated with higher transcript abundance, supporting a potential role in fungicide adaptation. Overall, our findings highlight structural variation, contrasting reproductive histories, and lineage-associated CNV as important contributors to diversification in P. hordei, providing insights for future rust pathogen surveillance and management strategies.

Cyp51 gene↗
PubMed1987

Characterization of genotypic and phenotypic variation in plaque-purified strains of HzSNPV Elkar isolate.

Twenty plaque-purified strains of Heliothis zea S-type nuclear polyhedrosis virus (HzSNPV) were characterized based upon restriction endonuclease digests of viral DNAs, structural protein profiles, and larval melanization response. Each of the 20 strains had a unique genotype. Genomic heterogeneity between strains was localized to 4 regions of the HzSNPV genome. Differences in protein profiles of occluded virus were noted for each strain relative to the wild-type isolate. The strains were separated into 3 groups based upon differences in relative virulence and rate of larval melanization upon death. There was no correlation between differences in pathology and specific alterations in either genotype or structural proteins. The genotype of strain HzS-15 was extensively characterized. Physical maps were constructed for the HzS-15 strain and all of the plaque-purified strains.

Animals↗
PubMed2003

Isolation and characterization of Escherichia coli recovered from Maryland apple cider and the cider production environment.

Contaminated apple cider has been implicated in several Escherichia coli O157:H7 outbreaks. In an attempt to investigate sources and modes of entry of E. coli into apple cider, samples of fresh apple, pomace, and cider and equipment and mill floor swabs were analyzed for standard plate counts (SPC), total coliforms (TC), fecal coliforms (FC), and E. coli. E. coli was isolated from 14 (33%) of 42 samples of bottled fresh cider, from food equipment in 6 (67%) of 9 mills, and from apples, pomace, or cider in 7 (78%) of 9 mills. Seventy-five E. coli isolates were further characterized for Shiga toxin-producing E. coli (STEC)-associated virulence factors, antimicrobial susceptibility, and pulsed-field gel electrophoresis (PFGE) type. No E. coli O157:H7 or other STEC was identified. Serotyping and PFGE revealed 64 distinct profiles, suggesting that recovered E. coli arose from multiple independent sources. However, on one occasion, E. coli isolated from the source apple sample was closely related to the E. coli identified in the finished cider sample. E. coli isolates were further tested for antimicrobial susceptibility to 17 antimicrobial agents of human and veterinary importance. Fourteen (19%) of the 75 isolates were resistant to at least one of the antimicrobial agents tested, and 9 (12%) were resistant to at least two of these agents. Of the resistant isolates recovered, 64% were resistant to tetracycline and 57% were resistant to streptomycin. Overall, the level of E. coli contamination in source apple samples did not differ significantly from those in samples of pomace, cider at the press, and cider entering the bottling tank; therefore, source apples cannot be dismissed as a potential contributor of E. coli to the cider-making process.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Biotyping and molecular phenotypic characterization of Bordetella bronchiseptica].

In the present study biochemical tests and outer membrane protein profile (OMP) capacity for typing Bordetella bronchiseptica field isolates were evaluated. The biochemical tests were performed by API 20NE system. OMP enriched fractions were obtained from cultures under virulent and modulated conditions and were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). We have identified five patterns by differences in the bands in the 85-95 kDa region (alpha, beta, gamma, delta and epsilon) from virulent cultures; and three different patterns by the flagellin expressed isotype from modulated cultures (A: 40 kDa, B: 45 kDa, and C: 40 and 45 kD simultaneously). Isotypes alpha, beta and gamma were linked to isotpye A, isotype delta to B and C, and isotypes epsilon to B. There is no evident correlation between characterized isotypes and the origin of the isolate. Nitrate reduction was the unique variable biochemical characteristic, only observed in rabbit isolates. It was possible to differentiate seven groups with the traits included in the study. The capacity of discrimination of the traits analyzed using the Hunter and Gaston index was 0.829.

Animals↗
PubMedDate not supplied

Comparison of two commercial enzyme-linked immunosorbent assays and conventional methods for avian serology.

Sera tested for hemagglutination-inhibition (HI) activity against Newcastle disease virus (NDV) and infectious bronchitis virus (IBV) and virus-neutralizing (VN) activity against infectious bursal disease virus (IBDV) and viral arthritis (VA) virus were collected from a wide variety of accessions into the Diagnostic Services Laboratory, Poultry Disease Research Center, University of Georgia. The sera were then segregated according to HI or VN titer to NDV, IBV, IBDV, or VA virus and stored frozen at -20 C until tested by two commercial enzyme-linked immunosorbent assays (ELISAs). There was good correlation of mean Flockchek ELISA titers or EIA Systems sample-to-positive (S/P) ratios with specific HI or VN titers. Flockchek ELISA profile group 3 and EIA Systems mean S/P ratio of 1.12 corresponded to what were considered in our lab to be minimum protective titers for each antigen against virulent challenge in our area.

Animals↗
PubMed2001

Toxoplasma gondii myosins B/C: one gene, two tails, two localizations, and a role in parasite division.

In apicomplexan parasites, actin-disrupting drugs and the inhibitor of myosin heavy chain ATPase, 2,3-butanedione monoxime, have been shown to interfere with host cell invasion by inhibiting parasite gliding motility. We report here that the actomyosin system of Toxoplasma gondii also contributes to the process of cell division by ensuring accurate budding of daughter cells. T. gondii myosins B and C are encoded by alternatively spliced mRNAs and differ only in their COOH-terminal tails. MyoB and MyoC showed distinct subcellular localizations and dissimilar solubilities, which were conferred by their tails. MyoC is the first marker selectively concentrated at the anterior and posterior polar rings of the inner membrane complex, structures that play a key role in cell shape integrity during daughter cell biogenesis. When transiently expressed, MyoB, MyoC, as well as the common motor domain lacking the tail did not distribute evenly between daughter cells, suggesting some impairment in proper segregation. Stable overexpression of MyoB caused a significant defect in parasite cell division, leading to the formation of extensive residual bodies, a substantial delay in replication, and loss of acute virulence in mice. Altogether, these observations suggest that MyoB/C products play a role in proper daughter cell budding and separation.

Alternative Splicing↗
PubMed1989

Identification of a high-virulence clone of type III Streptococcus agalactiae (group B Streptococcus) causing invasive neonatal disease.

Chromosomal genotypes of 128 isolates of six serotypes (Ia, Ib, Ic, II, Ic/II, and III) of Streptococcus agalactiae (group B Streptococcus) recovered predominantly from human infants in the United States were characterized by an analysis of electrophoretically demonstrable allelic profiles at 11 metabolic enzyme loci. Nineteen distinctive electrophoretic types (ETs), representing multilocus clonal genotypes, were identified. Mean genetic diversity per locus among ETs of isolates of the same serotype was, on average, nearly equal to that in all 19 ETs. Cluster analysis of the ETs revealed two primary phylogenetic divisions at a genetic distance of 0.65. A single clone (ET 1) represented by 40 isolates expressing type III antigen formed division I. Division II was composed of 18 ETs in three major lineages diverging from one another at distances greater than 0.35 and included strains of all six antigenic classes. The type III organisms in division I produce more extracellular neuraminidase and apparently are more virulent than the type III strains in division II, which are related to strains of other serotypes that cause disease much less frequently. The existence of this unusually virulent clone accounts, in major part, for the high morbidity and mortality associated with infection by type III organisms.

Genotype↗
PubMed2005

The Flo8 transcription factor is essential for hyphal development and virulence in Candida albicans.

The transcription factor Flo8 is essential for filamentous growth in Saccharomyces cerevisiae and is regulated under the cAMP/protein kinase A (PKA) pathway. To determine whether a similar pathway/regulation exists in Candida albicans, we have cloned C. albicans FLO8 by its ability to complement S. cerevisiae flo8. Deleting FLO8 in C. albicans blocked hyphal development and hypha-specific gene expression. The flo8/flo8 mutant is avirulent in a mouse model of systemic infection. Genome-wide transcription profiling of efg1/efg1 and flo8/flo8 using a C. albicans DNA microarray suggests that Flo8 controls subsets of Efg1-regulated genes. Most of these genes are hypha specific, including HGC1 and IHD1. We also show that Flo8 interacts with Efg1 in yeast and hyphal cells by in vivo immunoprecipitation. Similar to efg1/efg1, flo8/flo8 and cdc35/cdc35 show enhanced hyphal growth under an embedded growth condition. Our results suggest that Flo8 may function downstream of the cAMP/PKA pathway, and together with Efg1, regulates the expression of hypha-specific genes and genes that are important for the virulence of C. albicans.

Amino Acid Sequence↗
PubMed2005

Influence of nutrition on the production and physiology of sectors produced by the insect pathogenic fungus Metarhizium anisopliae.

Metarhizium anisopliae strains V245 and V275 differed in their stability when grown on different nutrient media. V275 produced fewer sectors than V245 irrespective of the cultural conditions. Both strains produced more sectors on nutrient rich media. At least four distinct types of sectors were produced in vitro. Most sectors were sterile or sporulated poorly and produced significantly lower quantities of virulence determining enzymes like Pr1. Real-time PCR confirmed differential expression of the pathogenicity-related genes pr1 A, ste 1, try 1, and chy 1 encoding for the subtilisin Pr1A, esterase, trypsin and chymotrypsin, respectively. API-ZYM revealed that the enzyme profiles of sectors differed from those of the parent cultures and also from other sectors. Sectors of M. anisopliae also produced less destruxins than the parent cultures independent of the strain.

Animals↗
PubMed2005

The contribution of MvfR to Pseudomonas aeruginosa pathogenesis and quorum sensing circuitry regulation: multiple quorum sensing-regulated genes are modulated without affecting lasRI, rhlRI or the production of N-acyl-L-homoserine lactones.

The transcriptional regulator MvfR is required for full Pseudomonas aeruginosa virulence, the function of multiple quorum sensing (QS)-regulated virulence factors and the synthesis of 4-hydroxy-2-alkylquinolines (HAQs), including the Pseudomonas quinolone signal (PQS). Here we investigate the role of MvfR in the QS circuitry and P. aeruginosa pathogenesis. We demonstrate using a combination of biochemical and molecular approaches, including transcription profiling, that MvfR is involved in the regulation of multiple P. aeruginosa QS-controlled genes without altering the expression of lasRI/rhlRI or the production of N-acyl-L-homoserine lactone (AHL) signals. Dissection of how mvfR is interwoven into the P. aeruginosa QS circuitry reveals that the MvfR system, through the essential contribution of PqsE, positively regulates a subset of genes dependant on both LasR and RhlR. Animal studies show that MvfR contributes to P. aeruginosa virulence by controlling the transcription of genes not under RhlR regulation, and that reduced virulence of a mvfR mutant is caused by the loss of pqsE expression and not only a deficiency in HAQs/PQS production. This study provides novel insights into the unique role of the MvfR system in AHL-mediated QS and further supports its importance in P. aeruginosa pathogenesis.

Animals↗
PubMed2006

Toxicogenomic response of Staphylococcus aureus to peracetic acid.

Staphylococcus aureus is responsible for many incidents of hospital-acquired infection, which causes 90,000 deaths and dollars 4.5 billion loss a year in the United States. Despite a wide use of disinfectants such as peracetic acid in health care environments, we certainly need better understanding of the effects of antimicrobial application on target pathogens to avert infection outbreaks. Consequently, herein, we explored for the first time the toxicogenomic response of S. aureus to a sublethal concentration of peracetic acid (1 mM) by using microarray-based transcriptome analysis. In particular, we investigated the dynamics of global gene expression profiles during its cellular response, which involved initial growth inhibition (10 min) and subsequent partial recovery (20 min). Further, we compared transcriptome responses to peracetic acid between S. aureus and Pseudomonas aeruginosa. Our findings show that (i) the regulation of membrane transport genes was significantly altered, (ii) DNA repair and replication genes were selectively induced, and (iii) primary metabolism-related genes were differently repressed between the two growth states. Most intriguingly, we revealed that many virulence factor genes were induced upon the exposure, which proposes a possibilitythatthe pathogenesis of S. aureus may be stimulated in response to peracetic acid.

Anti-Infective Agents↗