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R Wyler

Publications and source records attributed to R Wyler.

At least 19 recordsLinked to original sources
PubMed1990

Enzyme-linked immunosorbent assay for the detection of porcine epidemic diarrhea coronavirus antibodies in swine sera.

An enzyme-linked immunosorbent assay (ELISA) for detecting serum antibodies to the porcine epidemic diarrhea coronavirus (PEDV) was established by using cell culture-grown PEDV as antigen for coating. Ultracentrifugation through 20 and 45% (w/w) sucrose cushions proved to be the best antigen purification method. Examination of 1024 swine sera showed a high specificity and a greater sensitivity of the ELISA, when compared with indirect immunofluorescence. Reference sera with high antibody titers to PEDV originated from two pigs experimentally infected with PEDV. Three different antigen purification methods and the advantages of the ELISA compared with an immunofluorescence test are discussed.

Animals↗
PubMed1989

Quantitation, biological and physicochemical properties of cell culture-adapted porcine epidemic diarrhea coronavirus (PEDV).

The porcine epidemic coronavirus (PEDV), tentatively classified as a coronavirus, was adapted to Vero cells and a plaque test developed for infectivity titration, allowing us to test the biological and biophysical properties of the virus. Growth kinetics showed peak titers of 10(5.5) plaque-forming units ml-1 15 h after infection. Filtration experiments and electron microscopy revealed a particle diameter between 100 and 200 nm. The buoyant density of the virus was 1.18. The particle lost its infectivity on treatment with lipid solvents. Virus replication could not be inhibited by 5-iodo-2'-deoxyuridine. PEDV was moderately stable at 50 degrees C, but heat sensitivity was not altered by divalent cations. At 4 degrees C, the virus was stable between pH 5.0 and 9.0, but at 37 degrees C stability was restricted to the pH range 6.5-7.5. Viral infectivity was not impaired by ultrasonication or by multiple freezing and thawing. PEDV was not neutralized by transmissible gastroenteritis virus antiserum. On the basis of the tests carried out, PEDV is a pleomorphic, enveloped RNA virus with a particle diameter of approximately 150 nm and a buoyant density of 1.18. Infectivity depends on the presence of trypsin, and infected cells show a tendency to fuse and to form syncytia. All of these properties, as well as its physicochemical characteristics, allow PEDV to be classified as a coronavirus.

Animals↗
PubMed1988

Propagation of the virus of porcine epidemic diarrhea in cell culture.

Porcine epidemic diarrhea virus (PEDV) was adapted to serial propagation in Vero cell cultures by adding trypsin to the medium. PEDV-infected cells showed a distinct cytoplasmic fluorescence when examined by a fluorescent-antibody-staining technique. Cytopathic effects, such as vacuolation, formation of syncytia, and fusion of cells, were detected even at passage 1 of the PEDV in Vero cells. Once adapted, the virus induced numerous syncytia containing over 100 nuclei. From virus passage 5 on, all cells forming the monolayer were fused and totally destroyed within 24 h after inoculation. Cell culture-grown PEDV had typical coronavirus morphology when viewed by electron microscopy. Attempts to propagate PEDV in several primary and secondary fetal porcine cell cultures in the presence or absence of trypsin were unsuccessful.

Animals↗
PubMed1987

Murine glia cells in culture can be stimulated to generate reactive oxygen.

Induction of luminol-enhanced chemiluminescence (CL) indicative of reactive oxygen formation was studied in glia cell cultures from newborn mice. A burst of CL could be induced by phorbol myristate acetate, zymosan, and antibody-coated bovine red blood cells, whereas Sendai virus and several other agents known to induce CL in myeloid cells were ineffective. Sodium azide failed to inhibit CL, indicating a myeloperoxidase-independent mechanism of light emission. In parallel experiments we identified the cells binding antibody-coated erythrocytes as macrophages characterized by the reduction of nitroblue tetrazolium and phagocytosis of zymosan and latex particles. Brain macrophages may use reactive oxygen intermediates (ROI) as a mechanism of antimicrobial defence; and, on the other hand, ROI formed by these cells may contribute to immuno-pathology in the brain.

Acridines↗
PubMed1987

Inactivation of animal viruses during sewage sludge treatment.

Using a previously developed filter adsorption technique, the inactivation of a human rotavirus, a coxsackievirus B5, and a bovine parvovirus was monitored during sludge treatment processes. During conventional anaerobic mesophilic digestion at 35 to 36 degrees C, only minor inactivation of all three viruses occurred. The k' values measured were 0.314 log10 unit/day for rotavirus, 0.475 log10 unit/day for coxsackievirus B5, and 0.944 log10 unit/day for parvovirus. However, anaerobic thermophilic digestion at 54 to 56 degrees C led to rapid inactivation of rotavirus (k' greater than 8.5 log10 units/h) and of coxsackievirus B5 (k' greater than 0.93 log10 unit/min). Similarly, aerobic thermophilic fermentation at 60 to 61 degrees C rapidly inactivated rotavirus (k' = 0.75 log10 unit/min) and coxsackievirus B5 (k' greater than 1.67 log10 units/min). Infectivity of parvovirus, however, was only reduced by 0.213 log10 unit/h during anaerobic thermophilic digestion and by 0.353 log10 unit/h during aerobic thermophilic fermentation. Furthermore, pasteurization at 70 degrees C for 30 min inactivated the parvovirus by 0.72 log10 unit/30 min. In all experiments the contribution of temperature to the total inactivation was determined separately and was found to be predominant at process temperatures above 54 degrees C. In conclusion, the most favorable treatment to render sludge hygienically safe from the virological point of view would be a thermal treatment (60 degrees C) to inactivate thermolabile viruses, followed by an anaerobic mesophilic digestion to eliminate thermostable viruses that are more sensitive to chemical and microbial inactivations.

Anaerobiosis↗
PubMed1986

The genome of bovine herpesvirus 1 (BHV-1) strains exhibiting a neuropathogenic potential compared to known BHV-1 strains by restriction site mapping and cross-hybridization.

Bovine herpesvirus 1 (BHV-1) strains can be differentiated by their DNA and polypeptide patterns, and by antigenic properties as demonstrated by monoclonal antibodies. We classified the BHV-1 strains according to these data as BHV-1.1, BHV-1.2 (a/b) and BHV-1.3 (a/b). BHV-1.1 and BHV-1.2 correspond to the well known 'common' BHV-1 strains, whereas BHV-1.3 has only recently been recognized and exhibits a neuropathogenic potential. In the present paper we describe the structural genome characteristics of BHV-1.3 compared to those of the other BHV-1 strains, examined by means of restriction site mapping, electron microscopy and cross-hybridization. Our results also confirm and complete data concerning BHV-1.1 and BHV-1.2 published by other authors. The following main conclusions can be drawn from our investigations: BHV-1.1 and BHV-1.2 differences are restricted to distinct genomic regions, characterized by loss or gain of restriction sites. BHV-1.3, however, differs from the other BHV-1 strains in restriction site alterations throughout the whole genome. Electron microscopy showed the typical BHV-1 DNA structure for BHV-1.3. Genetic homology between BHV-1.1 and BHV-1.2, reported to be about 95%, was confirmed by cross-hybridization, and a similar high base sequence homology for BHV-1.3 could be shown.

Animals↗
PubMed1986

Genomic and antigenic comparison of an equine herpesvirus 1 (EHV 1) isolate from the 1983 Lippizan abortion storm with EHV 1 reference strains.

An EHV 1 isolate from the Lippizan Stud at Piber, which caused the abortion and paresis outbreak in 1983, was investigated using 3 known subtype 1 and 2 subtype 2 strains for comparison. Broad-scale restriction enzyme analysis as well as cross-neutralization with hyperimmune sera produced in rabbits were performed, and SDS-PAGE of infected cell proteins was conducted on a limited scale. The Piber isolate was clearly classified as a subtype 1 strain of EHV 1, and showed closest resemblance in its restriction patterns with a British EHV 1 strain, which originated from an outbreak with paretic symptoms. A second Piber isolate from the same outbreak examined to limited extent only was practically indistinguishable from the first one, as could have been expected. A thoroughly controlled systematic vaccination program with existing commercial vaccines against EHV 1 should protect the endangered Lippizan horses population against the abortigenic and less certainly against the paretic syndromes caused by this virus. According to data presented, a protection against respiratory disease is less probable.

Animals↗
PubMed1985

Analysis of parapoxvirus genomes.

Eight stomatitis papulosa (SP), four orf and two milker's nodes (MN) virus isolates were compared by restriction enzyme analysis. Considerable genetic heterogeneity was found not only between isolates belonging to the three different taxonomic groups but also between members of the same group. This heterogeneity precludes classification of parapoxviruses simply by comparison of their DNA cleavage patterns. Restriction maps were therefore prepared for 12 parapoxvirus DNAs. Fragments from defined regions of the genome were then selected and used as probes for cross-hybridizations to all other parapoxvirus DNAs. DNA fragments derived from an internal region of the genome hybridized strongly to all parapoxvirus isolates examined. In contrast, cross-hybridization of the end region of the DNA molecule was observed only between members of the same virus group. Molecular hybridization as a means of classifying parapoxvirus isolates is discussed.

DNA Restriction Enzymes↗
PubMed1985

European isolates of bovine herpesvirus 1: a comparison of restriction endonuclease sites, polypeptides, and reactivity with monoclonal antibodies.

Eleven European isolates of bovine herpesvirus 1 (BHV-1), together with two reference virus strains were compared by restriction endonuclease digestion, by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), and by their reactivity with a panel of monoclonal antibodies (McAb's). Based on the cleavage pattern of viral DNA with the restriction endonuclease Hind III the strains could be assigned to one of two established major virus types. Analysis by SDS-PAGE of viral polypeptides revealed that four protein species either displayed virus type or subtype specific minor variation of migration characteristics. Of 43 McAb's tested all reacted with all type 1 strains, whereas five antibodies failed to recognize some of the type 2 viruses. The existence of type specific variations among virus specified proteins was further evidenced by the recovery of one McAb recognizing type 1 viruses only. The data show that BHV-1 isolates can be assigned to established virus types according to the SDS-PAGE profile of viral proteins or the selective reactivity with type specific McAb's.

Animals↗