Biomedical subjects

R D Oberst

Publications and source records attributed to R D Oberst.

42 records · Page 3Linked to original sources

PubMed1989

Molecular cloning of serogroup- and serotype-specific genome segments from bluetongue virus serotype 11.

Genome segments 2, 6, 8, and 9 of bluetongue virus (BTV) serotype 11, coding for P2, NS1, NS2, and P6, respectively, were cloned into pUC 8. Sizes of segment-2 and segment-6 clones indicated partial copies (55% and 80% of full length, respectively), whereas segment 8 and 9 clones represented full-length copies. Northern blot hybridizations of the clones to the 5 United States BTV prototypic serotypes (2, 10, 11, 13, and 17) revealed segment-2 clone to be serotype-specific to BTV-11, whereas segment 6, 8, and 9 clones were able to detect all serotypes to varying degrees. All clones failed to detect the related orbivirus, epizootic hemorrhagic disease virus.

Animals↗

PubMed1987

Genetic reassortment of bluetongue virus serotype 11 strains in the bovine.

Reassortants of bluetongue virus Serotype 11 (BTV-11) were isolated from a yearling heifer experimentally infected with two electrophoretically different strains (UC-2 and UC-8) by subcutaneous inoculation. Viruses were recovered by direct titration of sonicated blood samples onto Vero cell monolayers, which were overlaid with agarose and later plaque purified. The parental electropherotype of UC-8 was identified as the predominant virus strain during the infection; UC-2 was not isolated. UC-2 infectivity was shown by reassortants which contained genome segments that were identical in migration pattern to the parental UC-2 electropherotype. The observations demonstrate that segmental reassortment can occur during mixed infections in the bovine, between strains of the same BTV serotype.

Animals↗

PubMed1987

Genome segment reassortment between two serotypes of bluetongue virus in a natural host.

The occurrence of genome segment reassortment between two antigenically related orbiviruses was demonstrated in cattle. Individual virus clones were isolated by cell culture plaque assays directly from the blood of a calf infected with two serotypes of bluetongue virus. The majority (89%) of progeny viruses isolated from the calf represented reassortant viruses. A minimum of six genome segments participated in reassortment, with 16 unique reassortant constellations being identified. Such genome segment reassortment between unique, though antigenically related, orbiviruses has undoubtedly played a major role in generating the extensive phenotypic and genotypic diversity that is characteristic of this serogroup.

Animals↗

PubMed1985

The coexistence of multiple bluetongue virus electropherotypes in individual cattle during natural infection.

Evidence of multiple genotypes of bluetongue virus (BTV) serotype 11 simultaneously infecting individual cattle was demonstrated in a California sentinel herd naturally infected with two BTV serotypes (11 and 17). Monitoring of weekly virus isolates by PAGE demonstrated genome segment diversity among BTV serotype 11 isolates and an individual bull simultaneously infected with multiple electropherotypes of this serotype. No electrophoretic variations were apparent in BTV serotype 17 isolates. The results of this study indicate that multiple plaque clonings and comparative electrophoresis are required to analyse BTV field isolates accurately for the presence of mixed infections.

Animals↗

PubMed1983

Demonstration of Anaplasma marginale in hemolymph of Dermacentor andersoni by animal inoculation and by fluorescent-antibody technique.

Hemolymph was collected from adult Dermacentor andersoni Stiles that had been infected with Anaplasma marginale Theiler as nymphs. Before hemolymph was collected, the adult ticks were either incubated and unfed at 37 C for 2.5 days or fed for 6 days on sheep. Hemolymph collected from groups of 100 ticks was inoculated into susceptible splenectomized calves. Smears of hemolymph from the same groups of ticks were prepared for examination by fluorescent antibody technique. Hemolymph from incubated ticks caused anaplasmosis in 2 of 4 trials, and hemolymph from feeding ticks caused anaplasmosis in 4 of 4 trials. Moderately fluorescing bodies were demonstrated in some hemocytes from incubated ticks, whereas hemocytes from feeding ticks contained numerous clusters of brightly fluorescing bodies. Fluorescing bodies were not observed in hemocytes from control ticks.

Anaplasma↗

PubMed1981

Staining characteristics of colonies of Anaplasma marginale Theiler in Dermacentor andersoni Stiles.

Colonies of Anaplasma marginale Theiler were studied in midgut epithelial cells of adult Dermacentor andersoni Stiles that were infected as nymphs. The colonies were demonstrated in plastic sections (1 micrometer) and frozen sections (6 micrometer) with Mallory's stain. Colonies were also demonstrated in frozen sections, using direct fluorescent antibody technique. Colonies were not observed in plastic or frozen sections stained by the Giménez method. In all preparations, the colonies were usually found near the basement membrane of the midgut tissue.

Anaplasma↗