Polydnavirus replication: the EP1 segment of the parasitoid wasp Cotesia congregata is amplified within a larger precursor molecule.

Polydnaviruses are unique viruses: they are essential for successful parasitism by tens of thousands of species of parasitoid wasps. These viruses are obligatorily associated with the wasps and are injected into the host during oviposition. Molecular analyses have shown that each virus sequence in the segmented polydnavirus genome is present in the wasp DNA in two forms: a circular form found in the virus particles and an integrated form found in the wasp chromosomes.

Functional analysis of the Saccharomyces cerevisiae DUP240 multigene family reveals membrane-associated proteins that are not essential for cell viability.

The DUP240 gene family of Saccharomyces cerevisiae is composed of 10 members. They encode proteins of about 240 amino acids which contain two predicted transmembrane domains. Database searches identified only one homologue in the closely related species Saccharomyces bayanus, indicating that the DUP240 genes encode proteins specific to Saccharomyces sensu stricto.

Detection of neutralizing antibodies to hepatitis C virus using a biliary cell infection model.

The identification and characterization of neutralizing anti-hepatitis C virus (HCV) antibodies may have a major impact on understanding HCV pathogenesis. However, to date, their detection has only been based on the inhibition of either the E2 envelope protein or HCV virions binding to different target cells. The permissiveness of primary biliary cells for HCV infection has been demonstrated previously.

Hepatitis C virus core protein expression in human B-cell lines does not significantly modify main proliferative and apoptosis pathways.

Hepatitis C virus (HCV) chronic infection has been associated with many lymphoproliferative disorders. Several studies performed on hepatoma and fibroblast cell lines suggest a role of the HCV core protein in activation of cellular transduction pathways that lead to cell proliferation and inhibition of apoptosis. However, no data are available concerning the effects of HCV core expression on B-lymphocyte proliferation and apoptosis.

The lon gene, encoding an ATP-dependent protease, is a novel member of the HAIR/HspR stress-response regulon in actinomycetes.

Members of a family of ATP-dependent proteases related to Lon from Escherichia coli are present in most prokaryotes and eukaryotes. These proteases are generally reported to be heat induced, and various regulatory systems have been described. The authors cloned and disrupted the lon gene and studied the regulation of its expression in Streptomyces lividans.

Assessment of the pathogenic potential of two Listeria monocytogenes human faecal carriage isolates.

Two human faeces carriage isolates of Listeria monocytogenes (H1 and H2) were compared to reference strains (ScottA and LO28) with regard to their lethality in 14-day-old chick embryos, their haemolytic and phospholipase (phosphatidylcholine-phospholipase C and phosphatidylinositol-phospholipase C) activities and their invasiveness towards Caco-2 cells. Experimental infection of chick embryos allowed discrimination of the strains into those exhibiting high virulence (ScottA and H2), those exhibiting slightly attenuated virulence (LO28) and those exhibiting low virulence (H1). A similar percentage mortality and time to death for embryos was observed when they were infected with H2 as was seen with infection by the reference strain ScottA.

Fine-scale genetic analyses reveal unexpected spatial-temporal heterogeneity in two natural populations of the commercial mushroom Agaricus bisporus.

This study examined the fine-scale genetic variation of the commercial mushroom, Agaricus bisporus, over 2 years at two sites in France. One site was a meadow fertilized with horse manure and disturbed regularly by humans; the other was a Monterey cypress forest free of human disturbance. Altogether, 50 mushrooms were collected and analysed for mitochondrial and nuclear genetic variation marked by RFLPs and multilocus enzyme electrophoretic polymorphisms.

Difference in substrate specificity divides the yeast alkali-metal-cation/H(+) antiporters into two subfamilies.

Yeast plasma membrane Na(+)/H(+) antiporters (TC 2.A.36) share a high degree of similarity at the protein level.

Interaction of human Tamm-Horsfall glycoprotein with Bordetella pertussis toxin.

Tamm-Horsfall glycoprotein (THP), which is synthesized by renal tubular cells, is the most abundant protein in normal human urine. Although its physiological function remains unclear, it has been proposed that THP may act as a defence factor against urinary tract infections by inhibiting the binding of S- and P-fimbriated Escherichia coli to renal epithelial cells. Because THP-related proteins are also found in the superficial layers of the oral mucosa, the authors investigated the ability of THP to interfere with the cytoadherence of pathogenic bacteria that colonize mucosal surfaces other than those of the urogenital tract.

MabA (FabG1), a Mycobacterium tuberculosis protein involved in the long-chain fatty acid elongation system FAS-II.

The fatty acid elongation system FAS-II is involved in the biosynthesis of mycolic acids, which are very long-chain fatty acids of the cell envelope specific to Mycobacterium tuberculosis and other mycobacteria. A potential component of FAS-II, the protein MabA (FabG1), was overexpressed and purified. Sedimentation equilibrium analyses revealed that MabA undergoes a dimer to tetramer self-association with a dissociation constant of 22 microM.

Shrimp Taura syndrome virus: genomic characterization and similarity with members of the genus Cricket paralysis-like viruses.

The single-stranded genomic RNA of Taura syndrome virus (TSV) is 10205 nucleotides in length, excluding the 3' poly(A) tail, and contains two large open reading frames (ORFs) that are separated by an intergenic region of 207 nucleotides. The ORFs are flanked by a 377 nucleotide 5' untranslated region (UTR) and a 226 nucleotide 3' UTR followed by a poly(A) tail. The predicted amino acid sequence of ORF1 revealed sequence motifs characteristic of a helicase, a protease and an RNA-dependent RNA polymerase, similar to the non-structural proteins of several plant and animal RNA viruses.

Antigenic and genetic diversity among swine influenza A H1N1 and H1N2 viruses in Europe.

Three subtypes of influenza A viruses, H1N1, H1N2 and H3N2, co-evolve in pigs in Europe. H1N2 viruses isolated from pigs in France and Italy since 1997 were closely related to the H1N2 viruses which emerged in the UK in 1994. In particular, the close relationship of the neuraminidases (NAs) of these viruses to the NA of a previous UK H3N2 swine virus indicated that they had not acquired the NA from H3N2 swine viruses circulating in continental Europe.

The Enterococcus faecalis gene encoding the novel general stress protein Gsp62.

The Enterococcus faecalis general stress protein Gsp62 was purified using two-dimensional gel electrophoresis and its 25 N-terminal amino acid sequence determined. Analysis of the corresponding gene revealed that the gsp62 product is a 172 aa protein. Transcriptional analysis of gsp62 gave evidence for a monocistronic mRNA, the synthesis of which was induced at the onset of stationary phase and in response to heat shock, acid pH, detergents (i.

Expression of hepatitis C virus envelope glycoproteins by herpes simplex virus type 1-based amplicon vectors.

Herpes simplex virus type 1 (HSV-1)-based amplicon vectors expressing hepatitis C virus (HCV) E1 and E2 glycoproteins were investigated. HSV-1 amplicon vectors carrying the E1E2p7- or E2p7-coding sequences of HCV type 1a under the control of the HSV-1 IE4 (alpha22/alpha47) promoter were constructed. Studies of infected HepG2, WRL 68 or Vero cells indicated that HSV-1-based amplicon vectors express high levels of HCV glycoproteins that are processed correctly.

Genotyping of axenic and non-axenic isolates of the genus Prochlorococcus and the OMF-'Synechococcus' clade by size, sequence analysis or RFLP of the Internal Transcribed Spacer of the ribosomal operon.

PCR amplicons of the Internal Transcribed Spacer (ITS) of the rrn operon of three axenic OMF (oceanic, marine and freshwater) strains of 'Synechococcus' (WH7803, PCC 7001 and PCC 6307, respectively) differ greatly in length from that of the axenic Prochlorococcus marinus subsp. pastoris PCC 9511(T), although these four cyanobacteria cluster relatively closely in phylogenetic trees inferred from 16S rRNA gene sequences. The ITSs of three strains (PCC 9511(T), PCC 6307 and PCC 7001) were sequenced and compared with those available for strains Prochlorococcus MED4 (CCMP 1378) and MIT9313 from genome sequencing projects.

Secretion of active anti-Ras single-chain Fv antibody by the yeasts Yarrowia lipolytica and Kluyveromyces lactis.

Yarrowia lipolytica and Kluyveromyces lactis secretion vectors were constructed and assessed for the expression of heterologous proteins. An anti-Ras single-chain antibody fragment (scFv) coding sequence was fused in-frame to different pre- or prepro-regions, or downstream from a reporter secretory gene (Arxula adeninivorans glucoamylase), separated by a Kex2 protease (Kex2p)-like processing sequence. Both organisms are able to secrete soluble scFv, with yields depending on the nature of the expression cassette, up to levels ranging from 10 to 20 mg l(-1).

Reductive iron uptake by Candida albicans: role of copper, iron and the TUP1 regulator.

High-affinity iron uptake by a ferrous permease in the opportunistic pathogen Candida albicans is required for virulence. Here this iron uptake system has been characterized by investigating three distinct activities: an externally directed surface ferric reductase, a membrane-associated PPD (p-phenylenediamine) oxidase and a cellular ferrous iron transport activity. Copper was required for the PPD oxidase and ferrous transport activities.

Monoclonal antibodies and human sera directed to the secreted glycoprotein G of herpes simplex virus type 2 recognize type-specific antigenic determinants.

Glycoprotein G-2 (gG-2) of herpes simplex virus type 2 (HSV-2) is cleaved to a secreted amino-terminal portion (sgG-2) and to a cell-associated carboxy-terminal portion which is further O-glycosylated to constitute the mature gG-2 (mgG-2). In contrast to mgG-2, which is known to elicit a type-specific antibody response in the human host, information on the immunogenic properties of sgG-2 is lacking. Here the sgG-2 protein was purified on a heparin column and used for production of monoclonal antibodies (mAbs).

Genetic polymorphism of human herpesvirus-7 among human populations.

The analysis of three human herpesvirus-7 (HHV-7) genes encoding phosphoprotein p100, glycoprotein B and major capsid protein respectively had previously shown the existence of distinct gene alleles, leading to the concept of HHV-7 variants. We have analysed the distribution of HHV-7 variants among 297 distinct subjects who belonged to different human populations from Africa, Asia, Europe and America. Two variants, designated Co1 and Co2, were found in 52% and 20% of studied subjects.

Gene transfer using human polyomavirus BK virus-like particles expressed in insect cells.

The major structural protein (VP1) of the BK polyomavirus (BKV) was expressed in the recombinant baculovirus expression system. Recombinant BKV VP1 was shown to self-assemble into virus-like particles (VLPs) with a diameter of 45-50 nm. As for other polyomaviruses, BKV VP1 has the capacity to bind to exogenous DNA.

Molecular epidemiology of simian T-lymphotropic virus (STLV) in wild-caught monkeys and apes from Cameroon: a new STLV-1, related to human T-lymphotropic virus subtype F, in a Cercocebus agilis.

A serological survey for human T-lymphotropic virus (HTLV)/simian T-lymphotropic virus (STLV) antibodies was performed in 102 wild-caught monkeys and apes from 15 (sub)species originating from Cameroon. Two animals (a Mandrillus sphinx and a Cercocebus agilis) exhibited a complete HTLV-1 seroreactivity pattern while two others lacked either the p24 (a Mandrillus sphinx) or the MTA-1/gp46 bands (a Pan troglodytes). Sequence comparison and phylogenetic analyses, using a 522 bp env gene fragment and the complete LTR, indicated that the two mandrill STLV strains belonged to the HTLV/STLV subtype D clade while the chimpanzee strain clustered in the HTLV/STLV subtype B clade.

Interaction of lyssaviruses with the low-affinity nerve-growth factor receptor p75NTR.

The low-affinity nerve-growth factor receptor p75NTR interacts in vitro with the rabies virus (RV) glycoprotein and serves as a receptor for RV. The Lyssavirus genus comprises seven genotypes (GTs) of rabies and rabies-related viruses. The ability of p75NTR to interact with the glycoprotein of representative lyssaviruses from each GT was investigated.

Interaction of human immunodeficiency virus type 1 Vif with Gag and Gag-Pol precursors: co-encapsidation and interference with viral protease-mediated Gag processing.

Interactions of human immunodeficiency virus type 1 (HIV-1) Vif protein with various forms of Gag and Gag-Pol precursors expressed in insect cells were investigated in vivo and in vitro by co-encapsidation, co-precipitation and viral protease (PR)-mediated Gag processing assays. Addressing of Gag to the plasma membrane, its budding as extracellular virus-like particles (VLP) and the presence of the p6 domain were apparently not required for Vif encapsidation, as non-N-myristoylated Deltap6-Gag and Vif proteins were co-encapsidated into intracellular VLP. Encapsidation of Vif occurred at significantly higher copy numbers in extracellular VLP formed from N-myristoylated, budding-competent Gag-Pol precursors harbouring an inactive PR domain or in chimaeric VLP composed of Gag and Gag-Pol precursors compared with the Vif content of Pr55Gag VLP.