Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 7 de 7
Filter
Add more filters










Database
Language
Publication year range
1.
Genome Res ; 11(10): 1706-15, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11591647

ABSTRACT

Campylobacter jejuni is the leading cause of bacterial food-borne diarrhoeal disease throughout the world, and yet is still a poorly understood pathogen. Whole genome microarray comparisons of 11 C. jejuni strains of diverse origin identified genes in up to 30 NCTC 11168 loci ranging from 0.7 to 18.7 kb that are either absent or highly divergent in these isolates. Many of these regions are associated with the biosynthesis of surface structures including flagella, lipo-oligosaccharide, and the newly identified capsule. Other strain-variable genes of known function include those responsible for iron acquisition, DNA restriction/modification, and sialylation. In fact, at least 21% of genes in the sequenced strain appear dispensable as they are absent or highly divergent in one or more of the isolates tested, thus defining 1300 C. jejuni core genes. Such core genes contribute mainly to metabolic, biosynthetic, cellular, and regulatory processes, but many virulence determinants are also conserved. Comparison of the capsule biosynthesis locus revealed conservation of all the genes in this region in strains with the same Penner serotype as strain NCTC 11168. By contrast, between 5 and 17 NCTC 11168 genes in this region are either absent or highly divergent in strains of a different serotype from the sequenced strain, providing further evidence that the capsule accounts for Penner serotype specificity. These studies reveal extensive genetic diversity among C. jejuni strains and pave the way toward identifying correlates of pathogenicity and developing improved epidemiological tools for this problematic pathogen.


Subject(s)
Campylobacter jejuni/genetics , Campylobacter jejuni/isolation & purification , Genome, Bacterial , Oligonucleotide Array Sequence Analysis/methods , DNA, Bacterial/chemistry , Genetic Variation , Humans , Nucleic Acid Hybridization , Polysaccharides, Bacterial/chemistry , Polysaccharides, Bacterial/genetics , Reproducibility of Results , Species Specificity
4.
J Virol ; 74(12): 5577-86, 2000 Jun.
Article in English | MEDLINE | ID: mdl-10823865

ABSTRACT

Heterosexual transmission of human immunodeficiency virus (HIV) is the most frequent mode of infection worldwide. However, the immediate events between exposure to infectious virus and establishment of infection are still poorly understood. This study investigates parameters of HIV infection of human female genital tissue in vitro using an explant culture model. In particular, we investigated the role of the epithelium and virucidal agents in protection against HIV infection. We have demonstrated that the major target cells of infection reside below the genital epithelium, and thus HIV must cross this barrier to establish infection. Immune activation enhanced HIV infection of such subepithelial cells. Furthermore, our data suggest that genital epithelial cells were not susceptible to HIV infection, appear to play no part in the transfer of infectious virus across the epithelium, and thus may provide a barrier to infection. In addition, experiments using a panel of virucidal agents demonstrated differential efficiency to block HIV infection of subepithelial cells from partial to complete inhibition. This is the first demonstration that virucidal agents designed for topical vaginal use block HIV infection of genital tissue. Such agents have major implications for world health, as they will provide women with a mechanism of personal and covert protection from HIV infection.


Subject(s)
Antiviral Agents/pharmacology , Cervix Uteri/virology , HIV Infections/prevention & control , HIV Infections/transmission , HIV-1/drug effects , HIV-1/physiology , Cell Polarity , Cells, Cultured , Cervix Uteri/cytology , Cervix Uteri/drug effects , Cervix Uteri/ultrastructure , Culture Techniques , DNA, Viral/biosynthesis , DNA, Viral/genetics , Epithelial Cells/drug effects , Epithelial Cells/ultrastructure , Epithelial Cells/virology , Female , Gramicidin/pharmacology , HIV Infections/virology , HIV-1/genetics , HIV-1/ultrastructure , Humans , Immunohistochemistry , Lymphocyte Activation/drug effects , Microscopy, Electron , Mucous Membrane/cytology , Mucous Membrane/drug effects , Mucous Membrane/ultrastructure , Mucous Membrane/virology , Naphthalenesulfonates/pharmacology , Nonoxynol/pharmacology , Phytohemagglutinins/pharmacology , Polymers/pharmacology , Premenopause , Virus Replication/drug effects
5.
Nucleic Acids Res ; 24(22): 4471-8, 1996 Nov 15.
Article in English | MEDLINE | ID: mdl-8948637

ABSTRACT

During the initial infection of B lymphocytes by Epstein-Barr virus (EBV) only a few viral genes are expressed, six of which encode the EBV nuclear antigens, EBNAs 1-6. The majority of EBNA mRNAs share common 5'-ends containing a variable number of two alternating and repeated exons transcribed from the BamHI W major internal repeats of the viral DNA. These sequences can also exist as independent small RNA species in some EBV-infected cell types. We present evidence that transcripts from these W repeat regions can exert a trans-acting effect on protein synthesis, through their ability to activate the dsRNA-dependent protein kinase PKR. UV cross-linking and filter binding assays have demonstrated that the W transcripts bind specifically to PKR and can compete with another EBV-encoded small RNA, EBER-1, which was shown previously to bind this kinase. In the reticulocyte lysate system the W RNAs shut off protein synthesis through an ability to activate PKR. In contrast to EBER-1, the W RNAs are unable to block the dsRNA-dependent activation of PKR. Using a purified preparation of the protein kinase we have shown that the W transcripts directly activate PKR in vitro. The results suggest that EBV has the ability both to activate and to inhibit PKR through the actions of different products of viral transcription.


Subject(s)
Herpesvirus 4, Human/genetics , Protein Serine-Threonine Kinases/metabolism , RNA, Viral/metabolism , Base Sequence , Exons , HeLa Cells , Humans , Molecular Sequence Data , Nucleic Acid Conformation , Protein Biosynthesis , Repetitive Sequences, Nucleic Acid , eIF-2 Kinase
7.
Biochimie ; 76(8): 770-8, 1994.
Article in English | MEDLINE | ID: mdl-7534482

ABSTRACT

This review describes the structure and function of the double-stranded RNA-dependent protein kinase (PKR) and its interaction with RNA activators and inhibitors. The abilities of small virally-encoded RNAs such as VAI RNA of adenovirus, the Epstein-Barr virus encoded (EBER) RNAs and the Tat-responsive region RNA of HIV-1 to bind to and regulate PKR are reviewed, and the physiological implications of such regulation for the control of viral replication and cell growth are discussed. The potential effects on the activity of PKR of other proteins that bind double-stranded RNA and/or small viral and cellular RNAs are also considered.


Subject(s)
Protein Serine-Threonine Kinases/metabolism , RNA, Viral/metabolism , Adenoviridae/genetics , Base Sequence , Gene Products, tat/metabolism , HIV-1/genetics , Herpesvirus 4, Human/genetics , Interferons/metabolism , Molecular Sequence Data , Protein Biosynthesis , eIF-2 Kinase , tat Gene Products, Human Immunodeficiency Virus
SELECTION OF CITATIONS
SEARCH DETAIL
...