Control of the induction of type I interferon by Peste des petits ruminants virus.

Peste des petits ruminants virus (PPRV) is a morbillivirus that produces clinical disease in goats and sheep. We have studied the induction of interferon-β (IFN-β) following infection of cultured cells with wild-type and vaccine strains of PPRV, and the effects of such infection with PPRV on the induction of IFN-β through both MDA-5 and RIG-I mediated pathways. Using both reporter assays and direct measurement of IFN-β mRNA, we have found that PPRV infection induces IFN-β only weakly and transiently, and the virus can actively block the induction of IFN-β. We have also generated mutant PPRV that lack expression of either of the viral accessory proteins (V&C) to characterize the role of these proteins in IFN-β induction during virus infection. Both PPRV_ΔV and PPRV_ΔC were defective in growth in cell culture, although in different ways. While the PPRV V protein bound to MDA-5 and, to a lesser extent, RIG-I, and over-expression of the V protein inhibited both IFN-β induction pathways, PPRV lacking V protein expression can still block IFN-β induction. In contrast, PPRV C bound to neither MDA-5 nor RIG-I, but PPRV lacking C protein expression lost the ability to block both MDA-5 and RIG-I mediated activation of IFN-β. These results shed new light on the inhibition of the induction of IFN-β by PPRV

Recombinant L and P protein complex of Rinderpest virus catalyses mRNA synthesis in vitro

Rinderpest virus belongs to the family of Paramyxoviridae, consisting of non-segmented negative senseRNA viruses. Viral transcription and replication are carried out by theRNAdependentRNApolymerase L protein which functions together with P protein as L–P complex. The exact events triggering the polymerase complex from transcription to replication function is poorly understood. In the present work, an in vitro transcription system has been described with partially purified L–P complex expressed in insect cells and viral genomic RNA. The relative abundance of each species of mRNA synthesized in vitro decreased from the 3 end of the genome to the 5 end similar to their abundance in virus infected cells. Recombinant L–P complex was unable to synthesize leader RNA suggesting the initiation of transcription from gene start site and not at the 3 end of the genome

Interfamilial transfer of amber suppressor gene for the isolation of amber mutants of mycobacteriophage I3

A suppressor-containing strain of Mycobacterium smegmatis SN2 was isolated by transferring an amber suppressor carried on the plasmid of Pseudomonas pseudoalcaligenes ERA through transformation. Amber mutants of mycobacteriophage I3 were isolated

The hemagglutinin–neuraminidase protein of peste des petits ruminants virus is biologically active when transiently expressed in mammalian cells

The genes coding for the surface glycoproteins hemagglutinin–neuraminidase (HN) of the peste des petits ruminants virus (PPRV) and hemagglutinin (H) of rinderpest virus (RPV) were cloned in a cytomagalovirus promoter driven expression vector and expressed transiently in mammalian cells. The protein expression was apparent 24 h after transfection and the expressed proteins were detected at the cell surface. The transiently expressed PPRV HN protein was found to be biologically active in possessing hemadsorption and neuraminidase activities. On the other hand, RPV H protein exhibited neuraminidase activity but was deficient in hemadsorption activity. The substrate specificity of the neuraminidase activity of these two proteins differed distinctly. The presence of neuraminidase activity in both PPRV HN and RPV H proteins is unusual among members of the morbillivirus genus

Cellular casein kinase II-mediated phosphorylation of rinderpest virus P protein is a prerequisite for its role in replication/transcription of the genome

Phosphoprotein P of rinderpest virus (RPV), when expressed in E. coli, is present in the unphosphorylated form. Bacterially expressed P protein was phosphorylated by a eukaryotic cellular extract, and casein kinase II (CK II) was identified as the cellular kinase involved in phosphorylation. In vitro phosphorylation of P-deletion mutants identified the N terminus as a phosphorylation domain. In vivo phosphorylation of single or multiple serine mutants of P protein identified serine residues at 49, 88 and 151 as phospho-acceptor residues. The role of P protein phosphorylation in virus replication/transcription was evaluated using the RPV minigenome system and replication/transcription of a reporter gene in vivo. P protein phosphorylation was shown to be essential for in vivo replication/transcription since phosphorylation-null mutants do not support expression of a reporter gene. Transfection of increased amounts of phosphorylation-null mutant did not support minigenome replication/transcription in vivo

Isolation and properties of a lectin from the seeds of Mimosa invisa L

A lectin has been purified from the seeds of Mimosa invisa L. by gel filtration and preparative Polyacrylamide gel electrophoresis. The purified lectin was homogeneous as judged by analytical Polyacrylamide gel electrophoresis, immunodiffusion and Immunoelectrophoresis. The apparent molecular weight is 100,000; the protein is a tetramer with two types of subunits (molecular weight 35,000 and 15,000). The lectin is a glycoprotein with approximately 21% carbohydrate and interacts with Sephadex and concanavalin A-Sepharose. It agglutinates erthrocytes non-specifically, does not agglutinate leucocytes and is not mitogenic, agglutinates Mimosa-nodulating Rhizobium and is a panagglutinin; the agglutination is not inhibited by several simple sugars. It is thermo-stable and has no metal ions