Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thirteen strains of human influenza virus producing in chick embryo cell (CEC) cultures either virions with low infectivity or no virions were studied. In CEC, most of the strains induced synthesis of viral RNA, polypeptides, and ribonucleoprotein and produced functionaly active haemagglutinin, neuraminidase and virions lower infectivity. The low infectivity of virions produced by strains of this functional group was due to disturbed cleavage of a polypeptide, haemagglutinin precursor, formed in CEC, into a heavy a light haemagglutinin chain. Two strains belonging to another functional group induced no synthesis of virus-specific macromolecules in CEC, but were able to adsorb onto the cells. With one of these viruses, no transcription of parental RNA could be detected in CEC. There was no relationship between the grouping of the studied strains into a certain functional group with their antigenic characteristics, the year of isolation, the passage history in chick embryos and human pathogenicity.
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PMID:Investigation on the mechanisms of the failure of human influenza virus to replicate in chick embryo cell cultures. 2 Jul 62

Influenza PR8 particles resulting from strong treatment with caseinase C are spikeless, devoid of neuraminidase and hemagglutinin 1 and 2 glycopeptides, and contain a Schiff-negative polypeptide of about 13,000 molecular weight which exists as traces in intact virions. Their M-protein polypeptide content is reduced to 50% of its original value, but there is no evidence of particle disruption nor of lipid release. They fix complement in the presence of both anti-M-protein antiserum and antiserum raised against a host polysaccharide. During exposure to caseinase C, an antigen is unmasked. It is type-specific and its identity with the M-protein is discussed.
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PMID:Impairment of the M-protein and unmasking of a superficial type-specific antigen by proteolytic treatment of influenza A virions with preservation of host-specific antigenicity. 6 30

The method of electrophoresis in a single polyacrylamide gel plate was used for comparative study on virion polypeptides mobility in human influenza A and B virus strains. Molecular masses of individual polypeptides and their portion in the virion were determined. No variations in the migration speed of nucleoprotein (NP) and membrane protein (MP) were found in strains belonging to the same genus, but there were differences in the migration speed of these proteins in the genus A and genus B. Significant differences in migration and the content of glycoproteins, particularly of the heavy chain of hemagglutinin (HAI) in the genus A strain having different subtypes of hemagglutinin, including strains A/WS/33 (HONI), A/FM/1/47 (HINI), A/Sing/1/57 (H2N2), A/Port Chalmers/73 (H3N2), as well as in the genus B in strains B/Lee/40, B/Yamagata/1/73, and B/Johanesbourg/56. No differences in the mobility of glycoproteins in strains similar in the antigenic specificity of hemagglutinin and neuraminidase were found. On the basis of the comparative analysis of virion polypeptide electrophoregrams, three new strains on influenza A virus isolated in December, 1977, were identified as belonging to the species A (HINI).
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PMID:[Electrophoretic mobility of polypeptides in different strains on human influenza A and B viruses]. 8 Aug 85

Variants of A/PR/8/34 (HON1) influenza virus, having hemagglutinin molecules with probably a single altered antigenic determinant, were isolated by growing the virus in the presence of the monoclonal hybridoma antibody PEG-1. The variants were analyzed by peptide mapping and characterized antigenically by using PEG-1 and four other monoclonal hybridoma antibodies to PR8 hemagglutinin. Peptide maps of the large hemagglutinin polypeptide, HA1, from 8 out of 10 variants showed a single changed peptide. This peptide from two of the variants was analyzed, and in each case a serine residue in the wild-type hemagglutinin was replaced by leucine in the variant. Although these eight variants showed identical peptide maps, one could be discriminated antigenically from the others with one of the hybridomas. (The peptide maps represented about one-third of the HA1 molecule.) Of the other two variants, one gave the same HA1 map as the wild type, but could be distinguished antigenically from wild-type virus by two of the hybridomas. The other was unique, and could be distinguished, both antigenically and by peptide mapping, from the other variants. Since a large number of the variants selected with PEG-1 showed the same peptide change, it is likely that this alteration in amino acid sequence (serine to leucine) was responsible for the inability of the variants to bind PEG-1 monoclonal antibody. We do not know, however, whether the changed amino acids were located within the antigenic sites or whether the change occurred somewhere else in the hemagglutinin molecule and altered the determinants through conformational changes.
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PMID:Antigenic drift in type A influenza virus: peptide mapping and antigenic analysis of A/PR/8/34 (HON1) variants selected with monoclonal antibodies. 8 90

Inorganic sulphate (35S) was incorporated into the haemagglutinin molecule of A/Memphis/1/71 (H3N2) influenza virus when a keratosulphate-like host antigen was also incorporated into the glycoproteins of virus grown in the chorioallantoic membrane of the embryonated hen's egg. Little or no 35S-sulphate was incorporated when this hose antigen was not present in the glycoproteins of virus grown in chick embryo kidney cells or in the chorioallantoic membrane of embryonated duck eggs. The presence of the keratosulphate-like host antigen was required for the stability of the haemagglutinin molecule in sodium dodecyl sulphate (SDS). The haemagglutinin molecules from virus grown in hens' eggs were stable in SDS, whereas those from virus grown in duck eggs or in chick embryo kidney cells were not and could not be isolated on cellulose acetate. Chemical analysis showed that there were 87 glucosamine residues and three molecules of sulphate per haemagglutinin subunit as calculated for a trimer molecule having a mol. wt. of 200 000. There was one sulphate molecule per HA1 polypeptide chain and this was associated with the slowest migrating carbohydrate-protein complex of an HA1 tryptic digest separated by polyacrylamide gel electrophoresis.
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PMID:Host antigen as the sulphated moiety of influenza virus haemagglutinin. 15 2

Mouse mammary tumor virus (MMTV) glycoproteins and nonglycosylated polypeptides were purified by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Primary amino groups were labeled with fluorescamine to enable visualization of MMTV polypeptides in the gels. Protein bands were sliced from the gels and eluted with 90 to 95% recovery. Eight MMTV polypeptides, including three of the major viral components as well as five minor proteins, were routinely obtained. Double diffusion assays and immunoelectrophoresis confirmed the retention of antigenicity identical to that of untreated MMTV virions. Antisera obtained from MMTV-free BALB/c mice immunized with these purified proteins reacted with the polypeptide immunogen as well as with detergent-disrupted MMTV virions from mouse milk or cell culture. Double diffusion assays using the specific mouse antisera failed to detect any cross-reactivity among the isolated polypeptides. A hemagglutination-inhibition assay demonstrated that the ability of MMTV virions to inhibit the hemagglutinating properties of influenza virus resides in the glycosylated polypeptides gp52, gp37.7, and gp33.
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PMID:Structural components of mouse mammary tumor virus. II. Isolation and purification of virion polypeptides. 20 97

The genome of influenza virus consists of eight segments of single-stranded RNA, each of which encodes a different polypeptide. In addition to the eight recognized gene products, the virus specifies a distinct smaller nonstructural polypeptide (NS2), which is translated from a separate species of virus-specific mRNA. The location on the virus genome of the gene encoding this polypeptide was investigated by hybridization of the NS2 mRNA with isolated subgenomic RNA species, and by correlation of the inheritance of a strain-specific NS2 with inheritance of particular genome RNA segments during recombination between two different virus strains. The genetic information for NS2 was found to reside in the smallest genome RNA segment of the virion, which also encodes the NS1 polypeptide. Considering the sizes of the molecules involved, it is likely that the coding sequences for the two polypeptides overlap.
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PMID:The smallest genome RNA segment of influenza virus contains two genes that may overlap. 29 Oct 39

In previous studies we showed that a ninth polypeptide with a molecular weight of approximately 11,000 (NS2) found in influenza virus-infected cells was unique, that it could be synthesized in vitro, and that its expression in vivo required early protein synthesis. On the basis of these results we suggested that one of the eight genome RNA segments of influenza virus codes for two polypeptides [Lamb, R.A., Etkind, P.R. & Choppin, P.W. (1978) Virology 91, 60-78]. We describe here differences in the electrophoretic mobility of the NS2 polypeptides of different strains of influenza A virus. These results provided further evidence that NS2 is virus coded and also made possible genetic studies using recombinants between two virus strains (HK and PR8) whose NS2 polypeptides differ. These studies showed that the gene for NS2 reassorts with that of the nonstructural polypeptide NS1, which is coded by genome segment 8. A mRNA for NS2 has been separated from that of NS1 and the other viral polypeptides by centrifugation and has been translated in vitro. Hybridization of genome segment 8 to the total mRNAs from infected cells specifically prevented the synthesis of NS2 and NS1. These results indicate that influenza virus genome segment 8 is transcribed into two separate mRNAs that code for two polypeptides, NS1 and NS2. Possible mechanisms for the transcription of the two mRNAs from either contiguous or overlapping genes are discussed.
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PMID:Segment 8 of the influenza virus genome is unique in coding for two polypeptides. 29 7

Present epidemic influenza is uncontrolled by immuno- or chemoprophylaxis. Mutants of varying antigenic composition arise with relatively high frequency in nature and are able to circumvent herd, or induced, immunity. Also, drug-resistant viruses can be selected in vitro and this resistance can be exchanged to other viruses by gene reassortment. Combined immuno- and chemoprophylaxis may provide a more effective approach to the ultimate control of the disease. Most antiviral compounds have been selected by random screening in the laboratory. Application of more specific enzyme assays such as the virion-associated RNA transcriptase assays may produce other compounds with a defined mode of action - semi-rational chemotherapy. RNA and polypeptide sequence studies are in progress elsewhere to define transcription and translation initiation sites or virus adsorption sites. Such knowledge could lead to a new generation of antiviral compounds. Specific delivery of virus inhibitory compounds is an interesting problem. Liposomes are lipid spheres, and these have been used for the delivery of antiviral compounds.
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PMID:Approaches towards rational antiviral chemotherapy. 46 Dec 75

Inhibitors of glycolysis, oxidative phosphorylation, protein synthesis, membrane Na&-K& transport and microfilament and microtubule function have been employed to elucidate the mechanism of influenza virus uptake by CAM and CEF cells. Electron microscopy demonstrated uptake of virus by viropexis in the presence of all these inhibitors. Utilizing a pulse labelling technique, virus entering CEF cells in the presence of inhibitors was shown to initiate specific virus polypeptide synthesis after neutralization of remaining extracellular virus and removal of the inhibitors. As a consequence of these findings an energy independent mechanism of viropexis has been proposed.
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PMID:Studies on the mechanism of influenza virus entry into cells. 47 43


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