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Biomedical subjects

R Wyler

Publications and source records attributed to R Wyler.

At least 37 records · Page 2Linked to original sources
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

Method for determining virus inactivation during sludge treatment processes.

A simple and reliable method is described which allows determination of virus inactivation rates during sludge treatment processes in situ. Bacteriophage f2 was adsorbed onto an electropositive membrane filter which was then sandwiched between two polycarbonate membranes with pores smaller than the virus diameter. The resulting sandwich was fixed in an open filter holder, and several such devices were connected before being exposed in sludge-digesting tanks. The device described prevented uncontrolled virus escape, but allowed direct contact of the various inactivating or stabilizing substances present in the environment tested with the virus adsorbed to the carrier membrane. After exposure to an environment, the surviving fraction of virus was eluted from the inner filter and determined by plaque counting. By using polycarbonate membranes without pores for sandwiching, the influence of temperature alone on virus inactivation could be measured. Thermophilic fermentation at 60 degrees C and at 65 kPa pressure led to a bacteriophage f2 titer reduction of 3.5 log10 units per h, whereas during thermophilic digestion at 54.5 degrees C titers decreased 1.2 log10 units per h. During mesophilic digestion an inactivation rate of only 0.04 log10 units per h was observed. Under these latter conditions, temperature had only a minor effect (19%) on virus inactivation, whereas at 54.5 degrees C during thermophilic digestion heat accounted for 32% of the total inactivation, and during thermophilic fermentation at 60 degrees C temperature and pressure were 100% responsible for virus denaturation.

Bacteriophages↗
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

A chemiluminescent assay for mycoplasmas in cell cultures.

A chemiluminescent assay for the detection of mycoplasma contamination of cell cultures is described. Cells (and supernatant) derived from mycoplasma-contaminated cultures stimulate a burst of luminol-dependent chemiluminescence in cell suspensions containing phagocytic effector cell types. The assay conditions for spleen cells, human and bovine polymorphonuclear leucocytes as the responder or indicator cells have been optimized. The chemiluminescent assay can be utilized for both monolayer and suspension cell cultures and is more sensitive than colony formation on agar plates and electron microscopy. Results are obtained within 3-5 h including the time required for the preparation of the indicator cells. CL can be measured in the tritium window of standard liquid scintillation spectrometers after switching off the coincidence circuit.

Cells, Cultured↗
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↗
PubMed1984

Antibody-free target cells stimulate chemiluminescence in polymorphonuclear leukocytes: an artifact due to mycoplasma contamination.

The generation of toxic oxygen species represents a significant mechanism in the killing of microorganisms and antibody-coated cells by phagocytic cells. We have investigated the possibility that antibody-free target cells stimulate reactive oxygen generation in polymorphonuclear leukocytes (PMNL) using the measurement of luminol-dependent chemiluminescence (CL). It was found that the induction of CL consistently correlated with a mycoplasma contamination of the target cells. Free mycoplasma organisms of two species found frequently as contaminants in cell culture also stimulated CL. Upon artificial infection with mycoplasma, cultured cells acquired the capacity to evoke CL generation in PMNL. Our experiments strongly suggest that the induction of reactive oxygen generation by antibody-free target cells is an artifact due to mycoplasma contamination of the target cell cultures.

Animals↗
PubMed1984

The DNA of an IPV strain of bovid herpesvirus 1 in sacral ganglia during latency after intravaginal infection.

Two calves were inoculated intravaginally with a strain of bovid herpesvirus type 1 (BHV-1, IBR/IPV) isolated from a cow with infectious pustular vulvovaginitis (IPV). The animals were killed during a latent stage of infection as characterized by seroconversion, absence of virus shedding and recrudescence of virus shedding after dexamethasone treatment. IPV-virus DNA was detected in 9 out of 20 sacral ganglia of the 2 calves. Of the sections, 7.2% (n = 250) contained 1 cell with IPV-virus DNA, which was restricted to the nucleus of neurons. In agreement with findings on herpes simplex virus infections, the viral DNA of BHV-1 is harbored in the local sensory ganglia. Virological and serological implications of the latent IPV infection are discussed.

Animals↗
PubMed1984

[1st cured case of bovine herpes mamillitis in Switzerland].

The first outbreak of bovine herpes mamillitis in Switzerland has been observed and diagnosed in autumn 1983. Bovid herpesvirus type 2 (BHV-2) could be isolated from lesions of the cows' teats and was characterized by its morphology and by serological methods. Serological examinations of all the animals of the affected herd did not reveal conclusive data relating to time and source of the primary infection. Questions concerning epidemiology, especially in view of latency, therapeutic and prophylactic possibilities are discussed.

Acyclovir↗