PubMed Health⌕ Search

Biomedical subjects

V Foulongne

Publications and source records attributed to V Foulongne.

10 recordsLinked to original sources
PubMed2005

[Epidemiology of Human Metapneumovirus in respiratory tract diseases of children: preliminary results].

BACKGROUND: Human metapneumovirus (hmpv) is a newly identified agent responsible for respiratory tract infections in children, especially before one year of age. A prospective epidemiological study is underway to better define the spectrum of the disease in France. PATIENTS AND METHODS: From November 2003 to November 2004, rhinopharyngeal aspirates were obtained from all children under five years of age admitted to the hospital with upper or lower airway symptoms. Viral identification was made using gene amplification. RESULTS: Among 355 evaluable samples to date, 34 were positive for hmpv genome. Mean age of infected children was 6.4 months, 20.5% were prematurely born infants. The prognosis is usually good. CONCLUSION: Our preliminary results are consistent with the available literature data. Further studies are needed to better define the exact frequency and morbidity of this newly recognized infection, both in hospital and community settings.

Child↗
PubMed2004

[Strategies for bacterial virulence genes identification].

One of the recent preoccupations of medical microbiology has been to characterise the mechanisms of virulence of bacterial pathogens at the molecular level. One hundred years after Koch, Stanley Falkow proposed a new, molecular version of Koch's postulates to define avirulence gene: (a) the gene confers a certain phenotype to the studied bacteria, (b) inactivation of the gene abolishes the phenotype, (c)reintroduction of the gene restores the wild type to the mutant. Although this strategy, based upon mutagenesis and the use of experimental models, allows the identification of many genes, it is not comprehensive. Other methods can be used to complete the identification of virulence factors such as differential expression, either at the level of transcription (transcriptome) or at the level of protein expression (proteome). All these techniques are now supported by the data from complete genome sequencing projects. The pool of information obtained from these approaches allows the definition of the 'virulome', which is the assembly of factors a pathogen requires for virulence. Understanding the virulome will open the way to the development of new strategies for vaccination or the development of new generation of antimicrobials.

Animals↗
PubMed2004

Ganciclovir resistance mutations in UL97 and UL54 genes of Human cytomegalovirus isolates resistant to ganciclovir.

Human cytomegalovirus (HCMV) resistance to ganciclovir results from mutations in viral phosphotransferase (UL97) and/or DNA polymerase (UL54) genes. The HCMV isolates from the blood of immunocompromised patients with persisting presence of the pp65 antigen in the blood in spite of ganciclovir therapy were tested for ganciclovir susceptibility by an immediate-early antigen plaque reduction assay, and the UL54 and UL97 genes were sequenced. Nine isolates from eight patients (six patients with acquired immune deficiency syndrome (AIDS), one liver transplant recipient and one renal transplant recipient) showed phenotypic resistance to ganciclovir. All these ganciclovir-resistant HCMV isolates harbored one or more of the following UL97 mutations: M460V, A594V, A594T, L595S, C603W, and M615V. Two isolates harbored the P522S mutation in the UL54 gene. The M615V mutation in the UL97 gene has not been reported earlier and its role in ganciclovir resistance remains to be elucidated. In ganciclovir-resistant HCMV isolates the UL54 gene was less frequently mutated than the UL97 gene. The P522S mutation was relatively frequent in UL54-mutated HCMV isolates.

Antiviral Agents↗
PubMed2003

[Species identification and molecular epidemiology of bacteria belonging to Ochrobactrum genus].

Two species of medical interest belong to the genus Ochrobactrum, Ochrobactrum anthropi and Ochrobactrum intermedium. They are members of the microbiota of soil and an increasing number of works report the isolation of O. anthropi from clinical specimen, especially from immunocompromised patients and nosocomial infection. Involving of each species in human infection is poorly estimated due to unclear differential phenotypic characters. We performed 16S rDNA sequencing for identification of 20 clinical isolates of Ochrobactrum sp. to the species level. Then, we studied the phenotype of each isolate especially, morphology, culture onto different media and at different temperatures, biochemical characters and antibiotics resistance pattern. Colony morphology after growth onto Trypticase-Soy and McConkey agar, culture at 45 degrees C onto Trypticase-Soja agar, presence of urease, and netilmycin, tobramycin and colistin resistance allowed identification of species. Ribotyping using HindIII and EcoRI gave a supplementary criterion for species determination but did not allow typing at the infra-species level. In contrast, Pulsed-Field Gel Electrophoresis showed high degree of polymorphism between strains and proved the clonality of certain isolates. Thus, this method could be a useful tool for molecular epidemiology of Ochrobactrum infections.

DNA, Ribosomal↗
PubMed2001

Brucellosis: a worldwide zoonosis.

Brucella is one of the world's major zoonotic pathogens, and is responsible for enormous economic losses as well as considerable human morbidity in endemic areas. Control of brucellosis requires practical solutions that can be easily applied to the field. Rapid DNA-based diagnostic tests for both humans and livestock have now proved themselves on an experimental level. Data on the virulence of Brucella suggest common mechanisms shared with plant pathogens and endosymbionts of the alpha-proteobacteria. Understanding virulence will have practical repercussions in the realms of vaccine development and, perhaps, development of new antibiotics. The first complete Brucella genome sequence will be released soon, and this will help greatly in our understanding of the biology and evolution of this pathogen.

Animals↗
PubMed2001

Aromatic compound-dependent Brucella suis is attenuated in both cultured cells and mouse models.

The aroC gene of the facultative intracellular pathogen Brucella suis was cloned and sequenced. The cloned aroC gene complements Escherichia coli and Salmonella enterica serovar Typhimurium aroC mutants. A B. suis aroC mutant was found to be unable to grow in a defined medium without aromatic compounds. The mutant was highly attenuated in tissue culture (THP1 macrophages and HeLa cells) and murine virulence models.

Animals↗
PubMed2000

Identification of Brucella suis genes affecting intracellular survival in an in vitro human macrophage infection model by signature-tagged transposon mutagenesis.

Bacteria of the genus Brucella are facultative intracellular pathogens which have developed the capacity to survive and multiply in professional and nonprofessional phagocytes. The genetic basis of this aspect of Brucella virulence is still poorly understood. To identify new virulence factors, we have adapted signature-tagged transposon mutagenesis, which has been used essentially in animal models, to an in vitro human macrophage infection model. A library of 1,152 Brucella suis 1330 tagged mini-Tn5 Km2 mutants, in 12 pools, was screened for intracellular survival and multiplication in vitamin D(3)-differentiated THP1 cells. Eighteen mutants were identified, and their attenuation was confirmed in THP1 macrophages and HeLa cells. For each avirulent mutant, a genomic fragment containing the transposon was cloned. The genomic DNA sequence flanking the transposon allowed us to assign functions to all of the inactivated genes. Transposon integration had occurred in 14 different genes, some of which were known virulence genes involved in intracellular survival or biosynthesis of smooth lipopolysaccharide (the virB operon and manB), thus validating the model. Other genes identified encoded factors involved in the regulation of gene expression and enzymes involved in biosynthetic or metabolic pathways. Possible roles in the virulence of Brucella for the different factors identified are discussed.

Brucella↗
PubMed1999

A homologue of the Agrobacterium tumefaciens VirB and Bordetella pertussis Ptl type IV secretion systems is essential for intracellular survival of Brucella suis.

Analysis of a TnblaM mutant of Brucella suis 1330, identified as being unable to multiply in Hela cells, allowed us to identify a 11 860 bp region of the B. suis genome encoding a type IV secretion system, homologous to the VirB system of Agrobacterium tumefaciens and the Ptl system of Bordetella pertussis. DNA sequence revealed 12 open reading frames (ORFs) encoding homologues of the 11 VirB proteins present in the pTi plasmid of Agrobacterium with a similar genetic organization, and a twelfth ORF encoding a putative lipoprotein, homologous to a protein involved in mating pair formation during bacterial conjugation and to adhesins used by Pseudomonas species to bind to plant roots. Phylogenetic trees based on the sequences of VirB4 and VirB9 protein homologues suggest that evolution of the systems from DNA transfer towards protein secretion did not stem from a single event but that the protein secretion systems have evolved independently. Four independent mutants in virB5, virB9 or virB10 were highly attenuated in an in vitro infection model with human macrophages. The virulence was restored by complementation with a plasmid containing the full virB region. The virB region appears to be essential for the intracellular survival and multiplication of B. suis.

Agrobacterium tumefaciens↗