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At least 19 recordsLinked to original sources
PubMed1978

Translation of ascites and mengovirus RNA in fractionated cell-free systems from uninfected and mengovirus-infected Ehrlich-ascites-tumor cells.

We have prepared homologous, fractionated, cell-free translational systems from uninfected and mengovirus-infected Ehrlich ascites tumor cells in order to determine what alterations occur following virus infection in the translational machinery of the host cell. Two major differences distinguish the system developed from infected cells. First, it has a 40% lower rate of protein synthesis, primarily a consequence of the rate of chain elongation, which is depressed to 60 amino acids/min from 90 amino acids/min in the system from uninfected cells. Second, at supraoptimal concentrations of Mg2+ and K+ the system from virus-infected cells supports the translation of mengovirus RNA but not host mRNA. These differences between the two systems may reflect specific changes which are responsible for the selective translation of mengovirus RNA in the infected cell. In both systems the optimal concentrations of polyamines, monovalent and divalent cations, mRNA, and ribosomal subunits are the same for the translation of either host or viral RNA. This uniformity is useful in experiments, designed to investigate the selective translation of viral RNA, where various components of the two systems are interchanged.

Animals↗
PubMed1980

the influence of the host cell on the inhibition of virus protein synthesis in cells double infected with vesicular stomatitis virus and mengovirus.

The ability of mengovirus to inhibit the synthesis of vesicular stomatitis virus (VSV) proteins and of VSV to inhibit the synthesis of mengovirus proteins during double infection in three different cell lines was investigated. Although cellular protein synthesis was inhibited after infection of cells by each virus, the ability of one virus to decrease translation of the mRNA species of the co-infecting virus varied with the cell type. Superinfection of mengovirus-infected L-929 cells by VSV resulted in essentially no inhibition in the synthesis of either mengovirus or VSV proteins. In HeLa cells and CHO cells the synthesis of both VSV and mengovirus proteins was inhibited under conditions of simultaneous or sequential infection. The inhibition of VSV protein synthesis after infection of HeLa cells by mengovirus was not a result of a modification or inactivation of virus mRNAs. When extracted from double infected cells, the VSV mRNAs manifested normal biological activity, as determined by their ability to stimulate the synthesis of VSV proteins in a micrococcal nuclease-treated cell-free system from L cells. The interference of non-interference of one virus by another in different cell lines was also measured by quantifying the number of infectious particles produced in each cell line. The results were similar to those reported above for protein synthesis inhibition. These experiments suggest that the interference of mengovirus with VSV mRNA translation in HeLa cells is not necessarily reflective of the mechanism by which mengovirus inhibits cellular protein synthesis. Also, the host cell appears to influence the extent or nature of the interference of one virus by the other.

Animals↗
PubMed1982

Genomic RNA of mengovirus V. Recognition of common features by ribosomes and eucaryotic initiation factor 2.

Binding of ribosomes to the 32P-labeled genomic RNA of mengovirus was studied in lysates of mouse L929 and Krebs ascites cells under conditions for initiation of translation. Upon total digestion with RNase T1, the 32P-labeled RNA protected in either 40S or 80S initiation complexes yielded four unique, large oligonucleotides. Each of these oligonucleotides occurred once in the viral RNA molecule. The same four oligonucleotides were recovered from 80S initiation complexes formed in lysates in which unlabeled mengovirus RNA had been translated extensively, indicating that recognition by ribosomes was not modulated detectably by a viral translation product. The recognition of intact, 32P-labeled mengovirus RNA by eucaryotic initiation factor 2 (eIF-2) was examined by direct complex formation. Fingerprint analysis of the RNA protected by eIF-2 against RNase T1 digestion yielded three T1 oligonucleotides that were identical to three of the four oligonucleotides protected in either 40S or 80S initiation complexes. A physical map of the large T1 oligonucleotides of the mengovirus RNA molecule was constructed, and the four protected oligonucleotides were found to map internally, within the region between the polycytidylate tract and the 3' end. For either ribosomes or eIF-2, the protected oligonucleotides could not be arranged in a continuous sequence, suggesting that they constitute at least two widely separated domains. These results show that ribosomes recognize and blind to more than a single sequence in mengovirus RNA, located internally in regions that are far removed from the 5' end of the molecule. eIF-2 itself binds with high specificity to mengovirus RNA, recognizing apparently three of the four sequences recognized by ribosomes.

Animals↗
PubMed1971

System of double infection between vaccinia virus and mengovirus.

When L cells are simultaneously infected with vaccinia virus and mengovirus, double interference in the replication of both viruses is observed. Superinfection of vaccinia virus-infected cells by mengovirus during the first 5 hr of infection reduces vaccinia virus yields to between 1 and 3% of controls. The yields of mengovirus are reduced to between 1 and 16% of controls, depending upon the time of superinfection. The replication of vaccinia deoxyribonucleic acid is not inhibited by mengovirus; it is only delayed. On the other hand, vaccinia multiplication severely hinders the replication of mengovirus ribonucleic acid. The double-infected system, at early times, synthesizes proteins that resemble those synthesized in the vaccinia virus-infected cells. Later in infection, however, the pattern is switched to proteins synthesized by mengovirus-infected cells. Possible mechanisms for this double interference in multiplication are discussed.

Animals↗
PubMed1983

Genomic RNA of mengovirus. VI. Translation of its two cistrons in lysates of interferon-treated cells.

The addition of low levels (40 ng/ml) of the synthetic double-stranded polyribonucleotide poly I:C to lysates of interferon-treated L-cells resulted in a strong inhibition (70 to 75%) of the in vitro translation of mengovirus RNA. Under these conditions, the rates of incorporation of [35S]methionine or formyl-[35S]methionine were depressed to a comparable extent. The sequences of mengovirus RNA recognized by ribosomes of interferon-treated cells at initiation of translation were compared with those present in initiation complexes formed by ribosomes of untreated controls. Fingerprint analysis revealed that the same sequences of mengovirus RNA were protected against nuclease attack by the 80S and the 40S initiation complexes formed in vitro in lysates of control or interferon-treated L-cells. Mengovirus RNA-coded proteins were labeled at their N-terminal end with formyl-[35S]methionine and digested to completion with trypsin. The resulting fragments were separated by high-voltage paper electrophoresis. Two different formyl-[35S]methionine-labeled N termini were resolved. Further analyses supported the notion that the two radioactive peaks originated in the initiation of translation at two different sites. This pattern did not change when mengovirus RNA was translated in lysates of interferon-treated cells.

Animals↗
PubMed1966

Respiration of mengovirus-infected L-929 cells.

Iglewski, W. J. (The Pennsylvania State University, University Park), and E. H. Ludwig. Respiration of mengovirus-infected L-929 cells. J. Bacteriol. 92:733-738. 1966.-Polarographic techniques were employed to study the oxidative metabolism of L-929 cells during a one-step mengovirus growth cycle. Virus maturation began 3.5 hr after infection and was complete with 7 hr. Virus maturation was accompanied by a decreased rate of endogenous respiration and an increased rate of oxidation of succinate and alpha-glycerophosphate by L-929 cells. The rate of glucose uptake was the same for mengovirus-infected and control L-929 cells. However, there was a decreased oxidation of glucose to carbon dioxide and a decreased production of lactic acid by L cells infected with mengovirus under aerobic conditions. Mengovirus was produced equally well under aerobic and anaerobic conditions. The implications of the alterations in metabolism with respect to virus synthesis are discussed.

Carbon Isotopes↗
PubMed1992

Molecular and structural basis of hemagglutination in mengovirus.

The molecular and structural basis of mengovirus hemagglutination (HA) was investigated by the comparison of nucleotide sequences of the entire capsid coding regions of an HA+ variant, two HA- mutants, 205 and 280, and two HA+ revertants of 205. The mutants were selected after acridine mutagenesis of mengovirus-37A, a heat-stable and HA+ variant that is neurotropic in mice. HA+ revertants of mutant 205 were isolated from brain tissue of mice inoculated with mutant 205. The nucleotide sequences were determined by consensus RNA sequencing using genomic RNA templates from purified virions. Two nucleotide differences were observed in the VP1 coding region of the RNA genomes of mutants 205 and 280 in comparison to the RNA sequences of 37A and the revertants. Interpretation of these data predict substitutions of two consecutive amino acids at residues 1231 (K to R) and 1232 (P to S) of VP1 which form part of the H-I loop of VP1 found at the icosahedral fivefold axis. Analysis of the amino acid substitutions in the context of the three-dimensional structure of the mengovirus-M capsid indicated that hemagglutination most likely involves residues found at the icosahedral fivefold axis and probably does not involve the residues that form the putative cellular receptor binding site (the "pit"). Eleven amino acid differences were observed between the structural proteins of mengovirus-M and 37A, five in VP1, three in VP2, and three in VP3.

Amino Acid Sequence↗
PubMed1978

Selective translation of mengovirus RNA over Host mRNA in homologous, fractionated, cell-free translational systems from Ehrlich-ascites-tumor cells.

The selective translation of viral RNA in mengovirus-infected Ehrlich ascites tumor cells was investigated using fractionated translational systems whose macromolecular components were derived entirely from uninfected or virus-infected cells. Both systems translate host mRNA from uninfected cells, host mRNA from virus-infected cells, and mengovirus RNA. In competition experiments, where viral RNA and host mRNA were translated together in systems from uninfected cells, the relative amounts of virus-specific and host-specific proteins synthesized were proportional to the relative concentrations of the RNA templates. In systems whose components were obtained from virus-infected cells, mengovirus RNA was preferentially translated. 70% of the selectivity found in the translational systems derived from infected cells was due to the initiation factor fraction, the remaining 30% to components of the pH 5 enzyme fraction. In addition, host mRNA isolated after virus infection is translated in vitro to a lower extent in the presence of mengovirus RNA than is host mRNA from uninfected cells.

Animals↗
PubMed1990

The alpha subunit of eucaryotic initiation factor 2 is phosphorylated in mengovirus-infected mouse L cells.

Infection of mouse L cells with mengovirus resulted in the activation of a protein kinase (PK) that selectively phosphorylated the small, 38,000-molecular-weight alpha subunit of eucaryotic initiation factor 2 (eIF-2) in vitro. The mengovirus-activated kinase was detected in vitro approximately 3 h after virus adsorption. The ratio of phosphorylated to unphosphorylated eIF-2 also increased in vivo between 3 and 7 h after adsorption. The virus-activated kinase fractionated with the ribosomal pellet and had a high affinity for DEAE-cellulose and Mono Q ion-exchange columns. Gel electrophoresis of the kinase activity eluting from the Mono Q column and silver staining of the gel revealed only one protein band with a molecular mass of 70 kilodaltons. The optimal assay conditions for the mengovirus-activated kinase paralleled those of the double-stranded RNA-activated PK (dsRNA-PK). Lysates from infected cells contained elements capable of activating partially purified dsRNA-PK. These elements were identified as double-stranded RNA by their sensitivity to double-stranded RNase. The phosphorylation of the alpha subunit of eIF-2 coincided with the synthesis of dsRNA in infected cells, suggesting that the mengovirus-activated kinase is the dsRNA-PK. The phosphorylation of the alpha subunit of eIF-2 correlated with the global inhibition of protein synthesis that occurs at late times after infection.

Animals↗
PubMed1996

Tandem mengovirus 5' pseudoknots are linked to viral RNA synthesis, not poly(C)-mediated virulence.

The RNA genomes from the cardioviruses, hepatoviruses, and aphthoviruses encode two to five tandem pseudoknots within their 5' untranslated regions. These pseudoknots lie adjacent to a pyrimidine-rich sequence, which in cardio- and aphthoviruses takes the form of a homopolymeric poly(C) tract. Seven deletion mutations within mengovirus pseudoknots PK(B) and PK(C) were created and characterized. tested in tissue culture, mengovirus genomes with alterations in PK(C) were viable but had small plaque phenotypes. Larger plaque revertants were isolated and partially characterized, and each proved to be a second-site pseudorevertant with (unmapped) changes elsewhere in the genome. The infectious PK(C) mutant viruses were highly lethal to mice, and deletions in this motif did not affect mengovirus virulence in the same manner as deletions in the adjacent poly(C) tract. In contrast, deletions in PK(B), or deletions which spanned PK(B) + PK(C), produced nonviable genomes. Cell-free translations directed by any of the altered PK sequences gave normal polyprotein amounts relative to wild-type mengovirus. But viral RNA accumulation during HeLa cell infection was dramatically impaired, even with the least disruptive of the PK(C) changes, suggesting the pseudoknots play an essential though undefined role in RNA synthesis and moreover that an intact PK(B) structure is critical to this function.

Animals↗
PubMed1976

Protein synthesis in postnuclear supernatants from mengovirus-infected Ehrlich ascites tumor cells.

The effect of mengovirus infection on the protein synthetic capacity of Ehrlich ascites tumor cells cultured in vitro was studied in vivo and in vitro employing postnuclear supernatants prepared at various times post-infection in the absence and in the presence of 1% Triton X-100. The amino acid incorporating activities of extracts obtained in the presence of the detergent were reduced by about 30% compared with the capacities of the corresponding postnuclear supernatants prepared in the absence of Triton X-100; but the course of the activity vs. time curve was not influenced by the detergent. Under the conditions employed, the postnuclear supernatants were unable to reinitiate protein synthesis once elongation of nascent polypeptide chains concomitant with ribosome runoff was completed. After mengovirus infection, a gradual disappearance of polysomes from postnuclear supernatants and a simultaneous accumulation of monosomes was observed. The protein-synthesizing activities of normal and infected cells were inversely proportional to the monosome concentrations of their corresponding extracts. Qualitatively, protein synthesis in intact cells and in postnuclear supernatants responded similarly to mengovirus infection. In both cases an initial reduction of host-specific amino acid incorporation was followed by a burst of viral protein synthesis. However, the two activity vs. time curves showed the following significant differences: 1) The activities of extracts from control cells and from mengovirus-infected cells nearly in the infectious cycle were low compared with the activities observed in vivo. 2) In the middle of the infectious cycle, the peak of viral protein synthesis occurred later and the activity was higher in vitro. 3) Finally, in the late period of the infectious cycle the postnuclear supernatants had considerable protein synthesizing activity, at a time when protein synthesis in vivo was nil.

Animals↗
PubMed1969

Host-dependent restriction of mengovirus replication.

Mengovirus infection of a restrictive cell line, Maden's bovine kidney (MDBK), results in a virus yield 1,000-fold less than that obtained from productively infected cell lines such as L cells or Ehrlich ascites tumor cells (EAT). Cells of both types of host systems are infected with comparable efficiencies and are completely killed as a consequence of infection. Infective center assays, coupled with the observation of total cell killing, suggest that comparable numbers of cells synthesize viral antigen and release virus in both types of host system. Viral-specific ribonucleic acid (RNA) synthesis is initiated and proceeds in an identical fashion for approximately 4 hr after the infection of MDBK, EAT, or L-cells. At this time, viral RNA synthesis in MDBK ceases, whereas viral RNA synthesis in EAT and L-cells continues at a linear rate. These results indicate that none of the early viral events leading to the initiation of viral-specific RNA synthesis constitutes the primary site of mengovirus restriction in MDBK. Rather it appears that the cessation of viral RNA synthesis in restrictive cells constitutes the primary limiting event. Based on its delayed interaction with mengovirus RNA synthesis, it appears that the host-related restrictive agent is initially compartmentalized and then released as a consequence of infection subsequent to those early events in mengovirus infection leading to the initiation and continued synthesis of viral RNA.

Animals↗
PubMed1971

Transport as the rate-limiting step in the incorporation of uridine into mengovirus ribonucleic acid in Novikoff rat hepatoma cells.

The incorporation of uridine into the nucleotide pool of actinomycin-treated, mengovirus-infected Novikoff rat hepatoma cells in culture follows simple Michaelis-Menten kinetics, and the apparent V(max) and K(m) values are similar to those for uridine transport by uninfected cells. Incorporation of uridine into mengovirus-specific ribonucleic acid (RNA) also follows Michaelis-Menten kinetics, and the apparent K(m) (about 10 mum) is approximately the same as for uridine transport. Inhibition of uridine transport by the presence of adenosine, persantin, or phenethyl alcohol inhibits simultaneously and to the same extent the incorporation of uridine into the nucleotide pool and into viral RNA, without affecting viral RNA synthesis per se. Phenethyl alcohol, however, also inhibits virus maturation. The inhibition of uridine incorporation into the nucleotide pool and into viral RNA is of the simple competitive type, indicating that transport into the cells is the rate-limiting step in the incorporation of uridine into mengovirus RNA. The results also indicate that treatment with actinomycin D or mengovirus infection does not affect uridine transport.

Biological Transport↗
PubMed1977

An investigation of the stability of messenger RNAs in cell-free, translational systems from uninfected and mengovirus-infected Ehrlich ascites tumor cells.

The stabilities and translation of Ehrlich ascites tumor cell poly(A)-containing mRNA and mengovirus RNA in fractionated cell-free protein synthesizing systems from uninfected and mengovirus-infected Ehrlich ascites tumor cells were studied. During incubation of the systems about 20% of the input RNA is reduced in size and associated with ribosomes engaged in polypeptide synthesis; the remainder is rapidly degraded by RNases. At the end of active translation, both mRNA and nascent proteins are bound to polysomes which are of the same size as those formed during active protein synthesis. The kinetics of protein synthesis closely follow those of RNA hydrolysis. The stabilities of mengovirus RNA and poly(A)-containing mRNA from Ehrlich ascites tumor cells are the same in both systems.

Animals↗
PubMed1987

Biological properties of mengovirus: characterization of avirulent, hemagglutination-defective mutants.

Biological properties of two mengovirus mutants, 205 and 280, were compared to those of wild-type virus. The mutants exhibited alterations in plaque morphology, hemagglutination, and virulence in mice, but were not temperature-sensitive. Agglutination of human erythrocytes by mengovirus was dependent on the presence of sialic acid on the erythrocyte surface; however, free sialic acid failed to inhibit hemagglutination. Glycophorin, the major sialoglycoprotein of human erythrocyte membranes, exhibited receptor specificity for wild-type virus, but not for mutants 205 or 280. Cross-linking studies indicated that glycophorin exhibited binding specificity for the alpha (1 D) structural protein. The LD50 titers for wild-type mengovirus were 7 and 1500 plaque forming units (PFU) in mice infected intracranially (IC) and intraperitoneally (IP), respectively. However, mice infected IC or IP with 10(6) or 10(7) PFU of mutant 205 or 280 did not exhibit symptoms indicative of virus infection. Revertants were isolated from the brains of mice infected with mutant 205, but not from the brains of mice infected with mutant 280. The biological characterization of the revertants indicated that hemagglutination and virulence may be phenotypically-linked traits.

Animals↗
PubMed1978

Purification of mengovirus by freon extraction and chromatography on protein-coated controlled pore glass.

Mengovirus, extracted from infected L-cell cultures with Freon 113 and concentrated from the aqueous phase with polyethyleneglycol, was chromatographed on protein-coated controlled pore glass (CPG). The covalent binding of protein to CPG is described. Further purification and concentration of mengovirus was achieved by isopycnic density gradient centrifugation in solutions of either CsCl or salts of iodinated benzoic acid derivatives. The described procedure is superior to conventional methods for the isolation and purification of large quantities of mengovirus. It yields highly purified virus preparations within a short time and a recovery of more than 50% of the starting infectivity.

Chemical Precipitation↗