Biomedical subjects

C W Mandl

Publications and source records attributed to C W Mandl.

43 records · Page 3Linked to original sources

PubMed1990

Establishment of PCR for the early diagnosis of herpes simplex encephalitis.

The early detection of herpes simplex encephalitis (HSE) represents a major problem in viral diagnostics. We have now established a test system based on PCR for the specific amplification of HSV-DNA in cerebrospinal fluid (CSF) samples followed by oligonucleotide hybridization. The test proved to be very sensitive. Five molecules of HSV 1 DNA still yielded positive signals after hybridization. The assay was applied to CSF samples from 6 patients with confirmed HSE. All except one CSF sample obtained from the 2nd to the 8th day after onset of neurological symptoms yielded positive results. The primers used also exhibit a certain degree of crossreactivity with HSV 2, as revealed by testing of a CSF sample from an HSV 2-infected child. No positive signals were obtained with human DNA and with DNA from CMV- and VZV-infected fibroblasts. Also 42 CSF samples of patients suffering from other diseases of the CNS yielded negative results. The present results indicate that the detection of HSV DNA in CSF by PCR represents a valuable tool for the early diagnosis of HSE.

Antibodies, Viral↗

PubMed1990

A single amino acid substitution in envelope protein E of tick-borne encephalitis virus leads to attenuation in the mouse model.

We have determined the virulence characteristics of seven monoclonal antibody escape mutants of tick-borne encephalitis virus in the mouse model. One of the mutants with an amino acid substitution from tyrosine to histidine at residue 384 revealed strongly reduced pathogenicity after peripheral inoculation of adult mice but retained its capacity to replicate in the mice and to induce a high-titered antibody response. Infection with the attenuated mutant resulted in resistance to challenge with virulent virus. Assessment of nonconservative amino acid substitutions in other attenuated flaviviruses suggests that a structural element including residue 384 may represent an important determinant of flavivirus virulence in general.

Amino Acid Sequence↗

PubMed1989

Genome sequence of tick-borne encephalitis virus (Western subtype) and comparative analysis of nonstructural proteins with other flaviviruses.

The genome sequence of tick-borne encephalitis (TBE) virus (Western subtype vaccine strain Neudoerfl) was determined. This extends the previously published sequence of the structural proteins to the nonstructural protein region and noncoding sequences at the 5'- and 3'-termini. The amino-termini of the individual proteins were assigned by comparison with other flavivirus sequences. Amino acid homology calculations between TBE virus and mosquito-borne flaviviruses were performed for all nonstructural proteins. An evolutionary tree based on protein NS1 is presented that reveals the molecular basis of relationships among flaviviruses. Tick-borne and mosquito-borne flaviviruses share a common hydrophilicity profile and also other features of their primary sequences, such as the presumably functional Gly-Asp-Asp sequence element within protein NS5. Other characteristics, such as the potential N-glycosylation sites of protein NS1 and a potential proteolytic cleavage site within protein NS4B, are conserved within the mosquito-borne group, but differ in the TBE virus sequence.

Amino Acid Sequence↗

PubMed1989

Characterization of antigenic variants of tick-borne encephalitis virus selected with neutralizing monoclonal antibodies.

Antigenic variants of tick-borne encephalitis virus were selected by the use of six neutralizing monoclonal antibodies (MAbs), each defining a different epitope of the envelope glycoprotein E. These variants were characterized with respect to antigenic changes by analysing the binding of each of 18 precisely mapped MAbs in ELISA and haemagglutination inhibition tests. The results yielded information about interrelations between epitopes exceeding that obtained previously from competitive binding studies. In addition, variants were tested for their specific haemagglutination activities, which revealed a significant reduction of this functional activity in one of the variants.

Animals↗

PubMed1989

Antigenic structure of the flavivirus envelope protein E at the molecular level, using tick-borne encephalitis virus as a model.

A model of the tick-borne encephalitis virus envelope protein E is presented that contains information on the structural organization of this flavivirus protein and correlates epitopes and antigenic domains to defined sequence elements. It thus reveals details of the structural and functional characteristics of the corresponding protein domains. The localization of three antigenic domains (composed of 16 distinct epitopes) within the primary structure was performed by (i) amino-terminal sequencing of three immunoreactive fragments of protein E and (ii) sequencing the protein E-coding regions of seven antigenic variants of tick-borne encephalitis virus that had been selected in the presence of neutralizing monoclonal antibodies directed against the E protein. Further information about variable and conserved regions was obtained by a comparative computer analysis of flavivirus E protein amino acid sequences. The search for potential T-cell determinants revealed at least one sequence compatible with an amphipathic alpha-helix which is conserved in all flaviviruses sequenced so far. By combining these data with those on the location of disulfide bridges (T. Nowak and G. Wengler, Virology 156:127-137, 1987) and the structural characteristics of epitopes, such as dependency on conformation or on intact disulfide bridges or both, a model was established that goes beyond the location of epitopes in the primary sequence and reveals features of the folding of the polypeptide chain, including the generation of discontinuous protein domains.

Amino Acid Sequence↗

PubMed1988

Sequence of the structural proteins of tick-borne encephalitis virus (western subtype) and comparative analysis with other flaviviruses.

Tick-borne encephalitis (TBE) virus (Western subtype strain Neudoerfl) was cloned and the sequence of 2450 nucleotides of the 5'-terminal region of the genome was determined. By amino acid sequencing and sequence comparisons with other flaviviruses the amino-termini of the structural proteins and protein NS1 were localized. Sequence homologies with other flaviviruses were determined and corresponded well to the established serological classification system of the Flavivirus family. N-Glycosylation sites were found to be conserved to a large extent among members of the same serological subgroup, but not between members of different subgroups. Hydrophilicity plots and sequence comparisons revealed that the TBE virus capsid protein exhibited features distinct from all other flaviviruses. Additionally, the capsid protein coding region of another natural isolate of TBE virus (strain ZZ-9) was sequenced in order to analyze why the capsid protein of this strain exhibited a significantly faster migration rate on SDS-polyacrylamide gels than other TBE virus strains.

Amino Acid Sequence↗

PubMed1986

Characterization of cells transformed by the human polyomavirus JC virus.

One unique feature of the prototype JC virus (JCV) (Mad 1) genome is the occurrence of a second TATA sequence within the early promoter region. A naturally occurring oncogenic variant of JCV (Mad 4) lacks this second TATA box. Several cell lines transformed by Mad 1, Mad 4 and simian virus 40 were characterized, in part to investigate whether the second TATA sequence is functional. S1 nuclease mapping of early JCV gene transcription products revealed a major set of start sites common to both Mad 1 and Mad 4 mRNAs. In addition, a second set of early transcripts was found exclusively in Mad 1 transformants, presumably positioned by the second TATA box. The presence of these unique mRNAs in the Mad 1-transformed cells did not appear to have any bearing on the other parameters investigated, including size and quantity of early viral proteins, integration patterns of viral DNA and growth properties of the cells.

Antigens, Viral, Tumor↗