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Dive into the research topics where Tamas M. Varsanyi is active.

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Featured researches published by Tamas M. Varsanyi.


Journal of General Virology | 1984

Purification, Morphology and Antigenic Characterization of Measles Virus Envelope Components

Tamas M. Varsanyi; Göran Utter; Erling Norrby

Measles virus haemagglutinin (H), fusion (F) and matrix (M) components were purified by affinity chromatography using monoclonal antibodies coupled to CNBr-activated Sepharose. H and M proteins were purified to homogeneity as determined by polyacrylamide gel electrophoresis by a single cycle of adsorption-desorption. The corresponding purification of the F protein required two cycles of adsorption-desorption. After the second adsorption an extra wash with 1 M-guanidine-HCl was employed to remove the contaminating cellular actin. Electron microscopic examination of the purified envelope proteins showed that, at pH 6.0, the H peplomers had a truncated conical shape (width 6.5 to 4 nm, length 16 nm), and the F peplomers had a club-like shape (dimensions of the oval head 6 X 9 nm, length 15 nm). Lengths of both peplomers were measured excluding their undiscernible hydrophobic part. The M component at pH 3.0 appeared as a rounded particle (diam. 8 nm, central accumulation of contrast 1.5 nm) suggested to include four to six M polypeptides. Rabbit hyperimmune sera were prepared against all three purified envelope components. These sera reacted only with the homologous antigen in radioimmunoprecipitation assays. Both antisera against the H and F components neutralized the virus and blocked virus-specific haemolysis, but only anti-H serum inhibited haemagglutination.


Virology | 1985

Isolation and characterization of the measles virus F1 polypeptide: Comparison with other paramyxovirus fusion proteins

Tamas M. Varsanyi; Hans Jörnvall; Erling Norrby

Abstract Measles virus fusion (F) protein has been isolated by immunoadsorption to a complex of monoclonal antibodies bound to protein A-Sepharose. The 41-kDa F 1 component of the fusion protein was obtained pure in high yield by preparative SDS-polyacrylamide gel electrophoresis. The amino acid composition of the F 1 chain was determined and the N-terminal sequence was analyzed for 40 residues. The structure determined is largely hydrophobic, with 24 residues of Val, Ile, Leu, Met, Phe, or Ala. Comparison with previously published data on the F 1 polypeptide of Sendai virus showed considerable similarity in amino acid composition. Extensive N-terminal sequence homologies with F 1 polypeptides of different paramyxoviruses are also noticed, including a nine-residue segment strictly conserved among four F 1 polypeptides studied, as well as a weaker but distinct and Glyrich sequence homology with the influenza A and B virus HA 2 polypeptides. The evolutionary conservation of the N-terminal region at the site of cleavage of surface glycoproteins of the two families of myxoviruses highlights its specialized function in membrane fusion.


Journal of General Virology | 1995

Protection of hamsters against experimental mumps virus (MuV) infection by antibodies raised against the MuV surface glycoproteins expressed from recombinant vaccinia virus vectors.

Sophie Houard; Tamas M. Varsanyi; Fabienne Milican; Erling Norrby; Alex Bollen

The fusion (F) and haemagglutinin-neuraminidase (HN) glycoproteins of mumps virus (MuV) have been produced in CV1 cells via vaccinia virus recombinants. Recombinant proteins accumulated in infected cells and were glycosylated. Upon reduction, the F protein product was completely converted into its subunits. Hamsters infected with vaccinia recombinants expressing either the F or HN proteins produced antibodies recognizing MuV antigens and neutralizing MuV infectivity in vitro. These antibodies provided protection against MuV-induced encephalitis in newborn hamsters.


Journal of General Virology | 1973

Incomplete Virus Particles of Adenovirus Type 16

Göran Wadell; Marie-Louise Hammarskjöld; Tamas M. Varsanyi

Summary Haemagglutinating populations of virus particles of adenovirus type 16 (I–VIII) were separated by isopycnic centrifuging in CsCl. One of these populations (V) contained complete virus particles. Fresh preparations of virus particles from all populations studied had a morphology indistinguishable from that of complete virus particles. The five lightest populations were shown to contain [3H]-thymidine and to be infective; dose-response relationships indicated the occurrence of a multiplicity-dependent infectivity of the incomplete virus particles. SDS-polyacrylamide gel electrophoresis of incomplete virus particles of the lightest population demonstrated that they were deficient in three polypeptides, but contained three other polypeptides which were not detectable in complete particles. One characteristic polypeptide of incomplete particles and another characteristic polypeptide of complete particles displayed high ratios of arginine over threonine.


Journal of General Virology | 1989

The mumps virus fusion protein mRNA sequence and homology among the paramyxoviridae proteins

Narayanasamy Elango; Tamas M. Varsanyi; Jan Kövamees; Erling Norrby

The complete nucleotide sequence of the fusion protein (F) mRNA of the virulent SBL-1 strain of mumps virus has been determined by sequencing cDNA clones and mRNA and confirmed by partially sequencing the genomic RNA. The mRNA was 1721 nucleotides long excluding the poly(A) sequence and had one long open reading frame which encoded a protein of 538 amino acids with a calculated Mr of 58,791. The predicted amino acid sequence had a proteolytic cleavage/activation site, Arg Arg His Lys Arg, cleavage at which yields proteins F2 and F1. The uncleaved protein contained three highly hydrophobic regions: (i) the amino-terminal signal peptide, (ii) the amino-terminal region of F1 and (iii) the carboxy-terminal membrane anchorage domain. There were seven potential N-glycosylation sites, two in F2 and five in F1. Comparison of the virulent strain F protein sequence with that of an avirulent strain of mumps virus showed a difference of 14 amino acids. Among paramyxoviruses, mumps virus fusion protein shows the highest degree of homology with the fusion proteins of simian virus 5 and Newcastle disease virus.


FEBS Letters | 1977

DNA restriction site mapping of adenovirus type 16 with BamI, EcoRI, HpaI AND SalI

Tamas M. Varsanyi; Gösta Winberg; Göran Wadell

Human adenoviruses are divided into four subgroups. DNA restriction (RE) site mapping of Ad 2 (member of subgroup III) has been performed with &m, BarnI, EcoRI, Hi&III, H’aI and SaZI [l] . The availability of these maps has enabled localization of ts-mutations [2], determination of the fraction of integrated viral genome in transformed cells [3] and mapping of early and late Ad 2 transcripts [4]. The moderately oncogenic adenovirus types belonging to subgroup I differ in several biological aspects from members of other subgroups [S-7]. Furthermore, members of subgroup I, represented by Ad 16, produce more incomplete virus-particles (i.e., virusparticles with DNA of less than unit size) than members of other subgroups [8]. Access to DNA restriction site maps is a prerequisite for analysis of the structure of these DNA molecules. The aim of this communication is to present the RE site maps of Ad 16 with EcoRI, BamI, HpaI and Sal1 since no RE site map of Ad-types belonging to subgroup I has been reported.


Virology | 1987

F1 Polypeptides of two canine distemper virus strains: Variation in the conserved N-terminal hydrophobic region

Tamas M. Varsanyi; Hans Jörnvall; Claes Örvell; Erling Norrby

The fusion protein of canine distemper virus was isolated by immunoadsorption from two virus strains, the rapidly growing Onderstepoort strain (forming large plaques) and the Convac vaccine strain (forming microplaques). The F1 subunits of the two fusion proteins were purified by preparative polyacrylamide gel electrophoresis. Direct amino acid sequence analysis revealed that 36-residue N-terminal regions of the proteins from the two strains are identical except at position 9, where Ala in the Convac strain is substituted by Val in the Onderstepoort strain. The two sequences show high homology with the previously determined N-terminal sequence of the F1 polypeptide of measles virus, and moderate homology with corresponding sequences of five paramyxoviruses, emphasizing the occurrence of an extensive conservation of these structures.


FEBS Letters | 1986

Measles virus hemagglutinin. Removal of the initiator methionine in the mature protein, and evidence for further processing to produce a 'ragged' end.

Tamas M. Varsanyi; Gunilla Lundquist; Erling Norrby; Hans Jörnvall

Measles virus hemagglutinin has been isolated by immunoadsorption. The total composition of the protein and its N‐terminal amino acid sequence give data matching the structure indirectly deduced from cDNA. However, direct analysis of the hemagglutinin also shows that the mature protein is proteolytically processed and has a partly heterogeneous N‐terminus. The initiator Met is removed, and non‐stoichiometrically also the second residue.


Virus Research | 1985

Isolation and characterization of the measles virus F1 Polypeptide. Comparison with other paramyxovirus fusion proteins

Tamas M. Varsanyi; Hans Jörnvall; Erling Norrby

Measles virus fusion (F) protein has been isolated by immunoadsorption to a complex of monoclonal antibodies bound to protein A-Sepharose. The 41-kDa F1 component of the fusion protein was obtained pure in high yield by preparative SDS-polyacrylamide gel electrophoresis. The amino acid composition of the F1 chain was determined and the N-terminal sequence was analyzed for 40 residues. The structure determined is largely hydrophobic, with 24 residues of Val, Ile, Leu, Met, Phe, or Ala. Comparison with previously published data on the F1 polypeptide of Sendai virus showed considerable similarity in amino acid composition. Extensive N-terminal sequence homologies with F1 polypeptides of different paramyxoviruses are also noticed, including a nine-residue segment strictly conserved among four F1 polypeptides studied, as well as a weaker but distinct and Gly-rich sequence homology with the influenza A and B virus HA2 polypeptides. The evolutionary conservation of the N-terminal region at the site of cleavage of surface glycoproteins of the two families of myxoviruses highlights its specialized function in membrane fusion.


Annals of the New York Academy of Sciences | 1980

GENETIC VARIABILITY OF ADENOVIRUSES

Göran Wadell; Marie-Louise Hammarskjöld; Gösta Winberg; Tamas M. Varsanyi; Gunnar Sundell

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Alex Bollen

Université libre de Bruxelles

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Claes Örvell

Karolinska University Hospital

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