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R Manservigi

Publications and source records attributed to R Manservigi.

63 records · Page 4Linked to original sources
PubMed1978

The structural proteins and glycoproteins of herpesviruses: a review.

The virions of different herpesviruses are similar with respect to the number and kinds of constituent polypeptides, in spite of variability in the structures of individual polypeptides. The total number of virion polypeptides and glycopeptides ranges from 20 to 30 for different viruses and, in general, no more than one-quarter of these polypeptides is detectable in naked nucleocapsids, implying that most of the virion polypeptides are acquired during the process of envelopment. Although the functions of most individual structural proteins have not been identified, one can predict that the nucleocapsid proteins serve primarily structural roles or may mediate packaging of the viral genome, that the non-glycosylated envelope proteins play essential roles in the process of envelopment and that the glycoproteins, which are probably all exposed to the virion surface, mediate adsorption to and penetration of the host cell. Two of the herpes simplex virus glycoproteins have been identified as targets of neutralizing antibodies and one of these proteins has been shown to mediate viral penetration, probably by promoting fusion between the virion envelope and cell surface membrane.

Capsid↗
PubMed1977

Cell fusion induced by herpes simplex virus is promoted and suppressed by different viral glycoproteins.

Some of the factors that regulate membrane fusion resulting in polykaryocyte formationhave been investigated, using the model system of human cells infected with mutants of herpes simplex virus (HSV). One of the mutant viruses used in this study (MP) failed to produce the viral glycoprotein designated C2--a nonlethal defect that has previously been correlated with the polykaryocyte-inducing phenotype of this and other mutant strains (wild-type strains of HSV usually induce the aggregation of infected cells rather than their fusion). The other mutant virus (tsB5), a temperature-sensitive conditional-lethal mutant, failed to produce glycoprotein B2 at non-permissive temperature, whereas the synthesis of all other viral products appeared to be normal. We produced and isolated seven recombinants of MP and tsB5 that expressed both of the parental alterations in glycoprotein synthesis. All of the re-combinant viruses induced the fusion of infected cells at 34 degrees (correlated with the absence of C2 expression) but were unable to cause cell fusion at 39 degrees (correlated with the absence of C2 and of B2 expression), even after infection at multiplicities high enough to ensure that all cells in the cultures synthesized viral macromolecules. These results and studies on the dominance or recessiveness of the fusion-inducing phenotype in mixed infections provide evidence that glycoprotein B2 plays a critical role in the promotion of cell fusion and that glycoprotein C2 can act to suppress fusion.

Cell Fusion↗
PubMed1975

Isolation and characterization of the plasma membrane from Yoshida hepatoma cells.

Plasma membranes isolated from Yoshida ascites hepatoma AH-130 by a modification of the method of T.K. Ray (Biochim. Biophys. Acta 196:1, 1970), were subfractionated into three fractions having densities (d) 1.12, 1.14 and 1.16 by discontinuous sucrose density-gradient. Membrane subfractions were characterized by electron-microscopy, by assay of marker enzymes and by lipid composition. All subfractions appeared to be essentially free from whole mitochondria, lysosomes and nuclei. Subfraction d 1.16 had the highest 5'-nucleotidase, Mg++-ATPase and (Na+ +K+)-ATPase activities; cytochrome c oxidase was undetectable in any fraction and glucose-6-phosphatase was measurable only in fraction d 1.14 and 1.16. Cyclic AMP phosphodiesterase was nearly equally distributed in the fractions. Adenylate cyclase, 5'-nucleotidase and Mg++-ATPase activities of tumor membrane were lower with respect to liver plasma membrane, while cyclic AMP phosphodiesterase and (Na" +K+)-ATPase were found to have similar activities in the two membrane preparations. With respect to liver membrane, hepatoma membrane contained a higher amount of glycolipids and a higher amount of phospholipids accounted for mainly by sphingomyelin, phosphatidylserine and phosphatidic acid. The possible significance of the decrease of adenylate activity in the hepatoma membrane is briefly discussed.

Animals↗
PubMed1974

Method for isolation and selection of temperature-sensitive mutants of herpes simplex virus.

A method for induction and selection of temperature-sensitive mutants of herpes simplex virus is presented. After the infected cells were treated with 5-bromodeoxyuridine, the virus was extracted by repeated freezing and thawing and cloned in microcultures which were then incubated at permissive temperature until viral plaques appeared. The microcultures were then replicated at nonpermissive temperature. Clones not forming plaques in these latter were further purified and examined for temperature-sensitive characteristics. Viral clones mutated in plaque-forming ability or in yield were obtained and preliminarily characterized.

Bromodeoxyuridine↗
PubMedDate not supplied

Plaque dissociation of herpes simplex viruses: biochemical and biological characters of the viral variants.

Polycaryocytogenic (P) and non-polycaryocytogenic, or aggregating (A), stable variants were selected from a herpes simplex virus type 1 (HSV-1) and from a herpes simplex virus type 2 (HSV 2) which had not been deliberately exposed to known mutagenic agents. The P variant of HSV-1 (FP) differed from the A variant (FA) in polypeptides and glycoprotein patterns, but no gross differences were evident between the two variants of HSV-2 (GP and GA). Each P variant proved more 'specific' than each A variant in immune neutralization tests. At high multiplicity, GP produced polycaryocytes but FP did not. Virulence tests in mice showed FP to be much more virulent than FA but GA to be more virulent than GP. Finally, A and P variants of each type could not be differentiated with respect to thermal resistance of virons, capacity to grow at high temperature, and buoyant density of DNA.

Cell Line↗