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Biomedical subjects

G Siegl

Publications and source records attributed to G Siegl.

14 recordsLinked to original sources
PubMed1992

Specific diagnosis of parvovirus enteritis in dogs and cats by in situ hybridization.

In a retrospective study, the fixed intestines of 10 dogs and 10 cats with intestinal lesions characteristic of parvovirus infection were assayed for the presence of parvovirus by in situ hybridization and immunohistochemistry. Parvoviral nucleic acid was localized by in situ hybridization in intestinal tissue in all 10 dogs and in nine of the 10 cats, whereas antigen was detected only in seven of 10 canine and eight of 10 feline intestines by immunohistochemistry. We conclude that an aetiological diagnosis can be established with a high degree of certainty by routine histology. Demonstration of the infectious agent by in situ hybridization, however, proves to be a valuable specific tool which allows an exact cellular localization of parvovirus in formalin-fixed, paraffin wax-embedded tissue sections.

Animals↗
PubMed1992

Replication of hepatitis A virus and processing of proteins.

Isolation and propagation of hepatitis A virus (HAV) in cell culture is routinely possible. All primary HAV isolates and most established virus strains, however, show a protracted replication behaviour and tend to establish a persistent infection. Rapidly replicating, cytolytic variant viruses can be selected from persistently infected cultures under distinct conditions. Factors critical for the outcome of HAV infection include the genetics of the virus, the physiological state of the infected cell, the presence of defective interfering particles, synthesis and encapsidation of viral RNA and possibly synthesis and processing of viral proteins. Analysis of the latter events have proved to be difficult. Only seven of the 11 peptides coded for by the HAV genome have been experimentally identified and the sequence of cleavages by which they are released from the precursor polyprotein is still a matter of discussion.

Animals↗
PubMed1992

Genetic relatedness of hepatitis A virus strains recovered from different geographical regions.

A pairwise comparison of the nucleic acid sequence of 168 bases from 152 wild-type or unique cell culture-adapted strains of hepatitis A virus (HAV) revealed that HAV strains can be differentiated genetically into seven unique genotypes (I to VII). In general, the nucleotide sequence of viruses in different genotypes differs at 15 to 25% of positions within this segment of the genome. Viruses from four of the genotypes (I, II, III and VII) were recovered from cases of hepatitis A in humans, whereas viruses from the other three genotypes (IV, V and VI) were isolated only from simian species developing a hepatitis A-like illness during captivity. Among non-epidemiologically related human HAV strains, 81 were characterized as genotype I, and 19 as genotype III. Within each of these major genotypes, there were two distinct groups (subgenotypes), which differed in sequence at approximately 7.5% of base positions. Each genotype and subgenotype has a characteristic amino acid sequence in this region of the polyprotein, with the most divergent genotypes differing at 10 of 56 residues. Strains recovered from some geographical regions belonged to a common (endemic) genotype, whereas strains from other regions belonged to several, probably imported, genotypes. Thus, HAV strains recovered in North America were for the most part closely related at the nucleotide sequence level, whereas in other regions, such as Japan and Western Europe, HAV strains were derived from multiple genotypes or sub-genotypes. These data indicate that patterns of endemic transmission can be differentiated from situations in which infections are imported due to travel.

Amino Acid Sequence↗
PubMed1991

Identification and characterization of incomplete hepatitis A virus particles.

The range of hepatitis A virus (HAV) particles generated during persistent infection of different cell lines was studied. Buoyant density and sedimentation analyses of cell extracts revealed a uniform profile of particles in all cell lines analysed except for BS-C-1 cells. The virion itself usually represented less than 50% of the total mass of virus antigen. A major portion of the antigen was associated with non-infectious, empty particles, which banded at 1.305 g/ml and 1.20 g/ml CsCl, and sedimented in sucrose gradients at 76S and 59S. Empty HAV particles were similar to those of poliovirus with respect to their physical stability and had the characteristic capsid protein content (VP0, VP1 and VP3). An additional RNA-containing particle, probably the provirion, represented only a minor species characterized by a buoyant density of 1.32 g/ml in CsCl and sedimenting at 130S.

Animals↗
PubMed1991

Retrospective study of myocardial canine parvovirus infection by in situ hybridization.

The diagnosis of myocardial canine parvovirus (CPV) infection used to depend on the presence of pathognomonic intranuclear inclusion bodies. The in situ hybridization technique, however, allowed to detect CPV specific nucleic acid in myocardial tissue where no inclusion bodies were found. Hence, we applied this technique to check formalin-fixed paraffin-embedded myocardial tissue from puppies with heart lesions for the presence of CPV. The tissues had been collected between 1977 and 1989. A biotinylated probe was used for in situ hybridization. This way CPV specific nucleic acid was detected in 3 dogs where CPV myocarditis had not been diagnosed on routinely stained slides because of the lack of intranuclear inclusion bodies. However, in spite of the application of the in situ hybridization technique no further myocardial CPV infection was detected in puppies with heart lesions from after 1979, confirming that the number of puppies with myocardial CPV infection declined after that year.

Animals↗
PubMed1990

In situ hybridization for the detection of human parvovirus B19 nucleic acid sequences in paraffin-embedded specimens.

Parvovirus infection of pregnant women leading to a transplacentar infection of the fetus may result in hydrops fetalis, and ultimately in intrauterine death of the fetus. In situ hybridization with a biotinylated as well as with a 35S-labeled probe for human parvovirus B19 was performed on formalin-fixed paraffin-embedded (FFPE) tissue from a fetus suffering from non-immunologic hydrops fetalis. Histology was suggestive of viral infection probably with human parvovirus. Parvovirus DNA could be detected and precisely localized mainly in the nuclei of erythroid precursors cells within fetal blood vessels of all organs examined. There was no detection of B19 nucleic acid in parenchymal cells of the placenta or the fetal organs, nor within maternal blood cells. These findings are in agreement with the well-known properties of animal parvoviruses to replicate exclusively in proliferating cells. Taking into consideration the problems in diagnosing human parvovirus infection by light microscopy, we conclude that in situ hybridization with an appropriate non-radioactive probe is a valuable, rapid and safe complementary detection method for the diagnosis and study of human parvovirus infections. The 35S-labeled probe is more sensitive than the biotinylated probe, but has the disadvantages of lower resolution of the signal, longer duration of the assay, the hazard of radioactivity and the shorter shelf-life of the probe.

Adult↗
PubMed1979

Propagation of human hepatitis A virus in a hepatoma cell line.

Hepatitis A virus (HAV) was isolated directly from human feces and propagated serially in an HBsAg producing human hepatoma cell line. No cytopathic effect was observed in the tissue culture and no detectable amounts of HAV were present in the tissue culture supernatant fluid. However, increasing amounts of hepatitis A antigen (HAAg) were detected by radioimmunoassay in the cell extracts obtained by freezing and thawing of cells. Specificity of the HAAg determination was shown by neutralization with convalescent sera of marmosets experimentally infected with the MS-1 strain of hepatitis A and by the absence of this neutralization with preinoculation sera. HAAg was first detected after four weeks in the cell extract of infected cultures after inoculation of 10(2)--10(4) tissue culture infectious doses of HAV from second passage.

Antigens, Viral↗
PubMed1978

Characterization and classification of virus particles associated with hepatitis A. I. Size, density, and sedimentation.

Virus-like particles were purified from stools of patients in an epidemic of hepatitis A in Germany. When reference MS-1 chimpanzee pre-inoculation and convalescent sera were used, the close serological relationship of the purified particles to well-known isolates of hepatitis A could be established. On the other hand, the physicochemical characteristics of the particles were determined in parallel to the characteristics of a marker parvovirus (LuIII) and a marker picornavirus (poliovirus type 2). It could be shown that the majority of the hepatitis A-associated particles band at 1.34 g/ml in CsCl and, like poliovirus, sediment at about 160S. In addition, a distinct hepatitis A antigen was observed, which banded at 1.305 g/ml and sedimented between 50 and 90S. A further component accumulated in the density range of between 1.38 and 1.44 g/ml. However, it seemed to be rather labile. Upon reisolation from CsCl and sedimentation in sucrose, it resolved into a 160S, a 90 to 100S, and a 50S form. The size of the 160S particles (27 to 29 nm) could be readily distinguished from that of the parvovirus (22 to 24 nm). It is concluded, therefore, that hepatitis A-associated virus particles are more likely to be classified with the picornaviruses than with the parvoviruses.

Centrifugation, Density Gradient↗
PubMed1978

Characterization and classification of virus particles associated with hepatitis A. II. Type and configuration of nucleic acid.

Virus particles banding at 1.34 g/ml in CsCl and sedimenting at 160S in sucrose gradients were isolated from fecal specimens of patients suffering from hepatitis. In the presence of 4 M urea and about 90% formamide, these particles released linear nucleic acid molecules of the kinked appearance characteristic of single-stranded RNA or single-stranded DNA. They could be distinguished from the nucleic acid of phage lambda added to the preparation as a marker for double-stranded configuration. Experiments in which the virus particles under investigation were incubated at pH 12.9 at 50 degrees C for 30 min revealed that their nucleic acid molecules were hydrolyzed as readily as the RNA genome of poliovirus type 2 analyzed in parallel. Both the single-stranded DNA of phage phiX174 and that of parvovirus LuIII, however, proved unaffected by this treatment, and the double-stranded DNA of phage lambda was denatured to single-stranded molecules. It was concluded, therefore, that the virus of human hepatitis A contains a linear genome of single-stranded RNA and has to be classified with the picornaviruses.

Coliphages↗
PubMed1976

Infection of newborn and fetal hamsters induced by inoculation of LuIII parvovirus.

The LuIII parvovirus was adapted to the newborn hamster and produced a systemic infection with massive intestinal hemorrhage. Inoculation of pregnant hamsters lead to transplacental infection of the fetuses and abortion. Most fetal deaths were observed in animals inoculated on days 8 and 10 of gestation. Virus was recovered from dead fetuses, placentas, and viable fetuses. Histological lesions were found in the heart, liver, kidney and CNS of infected fetuses.

Animals↗
PubMed1976

Multiplication of parvovirus LuIII in a synchronized culture system. III. Replication of viral DNA.

The replication of the single-stranded DNA (ssDNA) of parvovirus LuIII was studied in synchronized HeLa cells. After infection of the cells in early S phase, synthesis of a replicative form (RF) DNA became detectable as early as 9 h postinfection, i.e., after display of the cellular helper function(s) indispensable for the replication of LuIII virus. According to digestion with nuclease S1, hybridization studies, and electron microscopy, RF DNA is a linear, double-stranded molecule comparable in length to mature ssDNA. It sedimented around 15S in neutral solution and banded at 1.714 g/ml in CsCl. Moreover, replication of LuIII DNA obviously includes a further replicative intermediate DNA which sedimented in front of RF DNA and bore single-stranded side-chains. Newly synthesized DNA disappeared from pools containing both RF DNA and replicative intermediate DNA within 5 min and reappeared in progeny virions only after 15 min. Intranuclear accumulation of significant amounts of progeny ssDNA could not be detected. It was postulated, therefore, that newly synthesized ssDNA is immediately enclosed in a stable maturation complex and resists extraction by the method of Hirt (1967).

Cell Division↗
PubMed1976

Multiplication of parvovirus LuIII in a synchronized culture system. IV. Association of viral structural polypeptides with the host cell chromatin.

Newly synthesized structural polypeptides of parvovirus LuIII, VP1 (62,000 daltons) and VP2 (74,000 daltons), were detected in nuclei of synchronized, infected HeLa cells at 11 to 12 h postinfection, i.e., after cells had passed through the S phase of the cell cycle. At this time, most of intranuclear viral polypeptides were associated with the chromatin acidic proteins. However, 13 to 14 h postinfection, about one-third of intranuclear VP1 and VP2 also could be extracted in the fraction containing nuclear sap proteins. According to pulse-chase experiments, VP1 and VP2 accumulated in the chromatin with a time lag of 20 to 30 min. About 90% of these chromatin-associated viral polypeptides represented empty viral capsids. In addition, chromatin prepared at 14 h postinfection contained 90 to 95% of the total intranuclear viral 16S replicative-form DNA. Since viral replicative-form DNA and empty viral capsids seem to be associated specifically with cellular chromatin, we assume that this subnuclear structure is the site of the synthesis of progeny viral DNA and the formation of complete virions.

Capsid↗
PubMed1976

The parvoviruses.

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Adenoviridae↗