Proteins In Virus Particles Research Articles

Comparative studies on the nuclear polyhedrosis viruses of Lymantria monacha and L. dispar

Immunodiffusion and tube precipitation tests, polyacrylamide gel electrophoresis of virus polypeptides, and cross-transmission experiments suggest that two nuclear polyhedrosis viruses, one from Lymantria monacha and one from L. dispar, are partially related to each other, but not identical. The virus particle proteins seem to be more specific than the polyhedron proteins.

Effects of tannic acid and its related compounds upon Chikungunya virus.

The present report describes not only the effects of tannic acid (TA; belonging to hydrolyzable tannins) and its related compounds upon the infectivity of Chikungunya virus (CHIKV) but also the mechanism involved in this phenomenon. Our data show that TA inactivates CHIKV in vitro. Since the inactivating effect turned out to be pH-dependent and was suppressed by bovine serum albumin, it is most probable that the virus-inactivating capacity of TA is attributable to its preferential binding to proteins of virus particles. Examination on the virus-inactivating capacities of some TA-related compounds and comparison of their structures indicated that the active site of TA and its analogues might be the phenolic hydroxyl groups in their molecules. It seems that the active groups interact with the proteins of virus particles, resulting in a reduction or loss of viral infectivity. Discussion is made on the specificity of the actions of tannins and the possibility of application thereof to chemicals which are useful to investigate the nature and properties of viral proteins.

The properties of three baculoviruses from closely related hosts

The baculoviruses of three important and closely related pest insects, Spodoptera littoralis, S. exempta and S. frugiperda, were purified and several of their properties were compared. These include data on virus morphology, physical properties of the virus particle, serological properties, structural polypeptides, and viral DNA. The effect of the endogenous polyhedron alkaline protease on the polyhedron and virus particle proteins was also investigated. Biochemical and biophysical differences between the viruses were found which were reflected in their serological properties. The feasibility of using a simple serological technique for specific identification of each virus has been demonstrated.

Relations Between Poliovirus Polypeptides as shown by Tryptic Peptide Analysis

Poliovirus proteins were labelled in vivo with [35S]-methionine, and the major products of translation and cleavage were separated by electrophoresis and compared in terms of two-dimensional tryptic peptide maps visualized by autoradiography. The main intermediates p110 and p90 had few or no methionine-labelled sequences in common, but were both contained in, and therefore almost fully account for, the presumed primary translation product p210. The sequences of p79, a major stable product of cleavage and a non-structural protein, were almost completely contained in p90, which in turn is the major component of the larger intermediates p168 and p155. P110 is confirmed as the precursor of virus particle protein, and VP0 as the precursor of VP2. However, the sequences of p31, the other major product of translation that is not a stuctural protein, were not contained in any of the viral polypeptides mentioned above.

The Properties of the Sendai Virus Ribonucleoproteins Involved in Genome Transcription in Infected Cells

SUMMARY The properties and function of parental nucleocapsid-like particles (NLP) in the cytoplasm of Sendai virus-infected Ehrlich tumour cells were studied. The formation of NLP stems from partial uncoating of the virus particles leading to the loss of about 60% of the mol. mass of virus protein, the genome in the NLP being fully conserved. Uncoating proceeds at 37 °C, but not at 0 °C, and does not require the synthesis of protein and host RNA. NLP sedimentation rate (∼ 200S) and buoyant density in caesium chloride (1.34 g/ml) are fairly close to those of nucleocapsids produced in vitro by treatment of the virus with sodium deoxycholate. However, the following differences between the two types of structures are found: (i) NLP are sensitive to ribonuclease; (ii) NLP contain the largest virus particle protein in addition to the nucleocapsid protein; (iii) most molecules of parental RNA in NLP sediment slower than RNA of native virus particles (50S), this phenomenon apparently not being due to genome RNA degradation. The involvement of NLP in the parental genome transcription is deduced from the following observations: (i) NLP possess the RNA polymerase activity in vitro; (ii) virus-induced RNA synthesis can be detected in the infected cells at a stage when all cytoplasmic parental RNA seems to be in NLP; (iii) a part of newly synthesized virus-specific RNA is associated with NLP; the kinetics of labelling suggest that the RNA is synthesized in NLP and released after synthesis.

Virus RNA and Protein Synthesis in Cells Infected with Different Strains of Newcastle Disease Virus

SUMMARY The virus RNAs and proteins synthesized in chick embryo cells infected with different strains of Newcastle disease virus have been characterized by polyacrylamide gel electrophoresis. By comparison of the rates of electrophoretic mobility of virus RNA with those of RNA molecules of known molecular weight, the molecular weights were estimated to be 4.8 × 106 for the virus particle RNA and 2.5 × 106, 1.1 × 106 and 0.4 to 0.7 × 106 for the RNA molecules synthesized in infected cells, the latter being heterogeneous. Synthesis of a number of virus particle proteins was readily detected.

Reovirus: analysis of proteins from released and cell-associated virus.

SUMMARY The proteins of purified preparations of reovirus type 3 have been examined using polyacrylamide gel electrophoresis. Preparations of cell-associated virus grown with foetal calf serum show three major peaks, λ, µ, σ, and several minor peaks. Preparations of released virus grown without foetal calf serum show only the three major peaks, suggesting that the minor peaks are not virus proteins. Analysis of preparations of released virus labelled with both [14C]lysine and [3H] leucine shows that each of three major peaks contains more than one polypeptide chain. The molecular weights of the polypeptides are: 140,000 to 150,000 for the λ group, 75,000 to 85,000 for µ and 36,000 to 44,000 for σ, as determined by migration in 5% sodium dodecyl sulphate-polyacrylamide gels. There are at least eight polypeptide chains distributed as two in peak λ, three in peak µ, and three in peak σ. Top component particles isolated during purification of virus show the same three protein peaks as demonstrated in complete virus. Virus cores produced by trypsin or chymotrypsin treatment of the virus lack µ-group polypeptides and some σ polypeptides. Radioactive glucosamine and fucose are not incorporated into any of the three groups of virus particle proteins during the growth cycle. The content of amino sugar or methylpentose in purified virus is less than 0.1% and that of neutral carbohydrates less than 1%. These results indicate that purified preparations of reovirus type 3 contain little if any carbohydrate. Such purified preparations agglutinate ox red blood cells.

Biochemical changes in the larvae of the variegated cutworm, Peridroma saucia, after infection with a nuclear-polyhedrosis virus

Nuclear-polyhedrosis-virus infection causes a decrease in total solids contents of the hemolymph of larvae of the variegated cutworm, Peridroma saucia. This decrease is partially caused by a decrease in hemolymph protein concentration and in free amino acids during the disease. An increase was found in the concentration of certain keto acids after infection. Nuclear polyhedrosis also causes an increase in transaminase activity in the fat body and in the intact organism. The amino-acid composition of the combined inclusion-body and virus-particle proteins was determined and found to be very similar to that reported in the literature by other workers.