Spleen cells from Rfv-3r/s mice with Friend virus-induced erythroleukemia were analyzed for expression of virus-induced proteins with monoclonal antiviral antibodies and conventional antisera. Leukemic spleen cells, 30-60 d after virus inoculation, expressed decreased amounts of ecotropic Friend murine leukemia helper virus gag- and env-encoded cell surface and intracellular proteins compared w...

Regulation of the terminal stage of viral DNA development, DNA packaging, is poorly understood. A new phage T4 in vitro DNA packaging assay employed purified proheads, terminase (gp17 + gp16), and ATP to encapsidate DNA resistant to nuclease. Mature phage T4 DNA and linearized plasmid DNAs containing or lacking a cloned T4 gene were packaged with high (approximately 10%) efficiency. Supercoiled...

The aim of this study was to determine the immunomodulatory effects of IL-12, IL-18 and CD154 (CD40 ligand, CD40L) in DNA-vaccination against the classical swine fever virus. Four recombinant plasmids were constructed including the CSFV coding region for the glycoprotein gp55/E2 alone or together with porcine IL-12, IL-18 or CD154 genes. Five groups of four pigs each were immunized intramuscula...

The bacterial RNA polymerase (RNAP) recognizes promoters through sequence-specific contacts of its promoter-specificity components (sigma) with two DNA sequence motifs. Contacts with the upstream ('-35') promoter motif are made by sigma domain 4 attached to the flap domain of the RNAP beta subunit. Bacteriophage T4 late promoters consist solely of an extended downstream ('-10') motif specifical...

Yeast forms of Paracoccidioides brasiliensis grown in liquid medium produced exocellular components. Immunodiffusion reactions and immunoprecipitations of 131I-radiolabeled antigenic components with sera from patients having paracoccidioidomycosis (PCM) were used to monitor the isolation of specific constituents. Components having the main antigenic activity (fCon A) were isolated by exclusion ...

Bacteriophage O1 is a Myoviridae A1 group member used historically for identifying Salmonella. Sequencing revealed a single, linear, 86,155-base-pair genome with 39% average G+C content, 131 open reading frames, and 22 tRNAs. Closest protein homologs occur in Erwinia amylovora phage φEa21-4 and Escherichia coli phage wV8. Proteomic analysis indentified structural proteins: Gp23, Gp36 (major tai...

This review describes a mechanism of viral transformation involving activation of cellular signaling pathways. We focus on four viral oncoproteins: the E5 protein of bovine papillomavirus, which activates the platelet-derived growth factor beta receptor; gp55 of spleen focus forming virus, which activates the erythropoietin receptor; polyoma virus middle T antigen, which resembles an activated ...

The membrane glycoprotein (gp55) encoded by the env gene of Friend spleen focus-forming virus (SFFV) causes mitogenesis of infected erythroblasts and is inefficiently (3-5%) processed from the rough endoplasmic reticulum (RER) to plasma membranes. Recent evidence suggested that gp55 binds to erythropoietin receptors (EpoR) in the RER, and it was proposed that this intracellular interaction caus...