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D L Knudson

Publications and source records attributed to D L Knudson.

At least 55 records · Page 3Linked to original sources
PubMed1984

Physical map of SeMNPV baculovirus DNA: an AcMNPV genomic variant.

A physical map of the plaque-purified SeMNPV-25 baculovirus DNA was constructed with HindIII, EcoRI, PstI, SstII, BstEII, BamHI, KpnI, and SmaI by multiple-enzyme digestion and DNA-DNA hybridization. The orientation of the physical map was to the AcMNPV polyhedrin gene, and a total of 104 restriction sites were ordered. The genome size was 131.89 kilobase pairs (87.05 X 10(6) Da). The physical maps of SeMNPV-25 DNA and AcMNPV-E2 DNA were compared, and they were similar except in four regions. Since the differences between the physical maps of SeMNPV-25 and AcMNPV-E2 were reconciled, the BstEII and SstII fragments for AcMNPV-E2 were also ordered. In addition, reiterated sequences in the SeMNPV-25 genome were identified and located on the physical map.

Base Sequence↗
PubMed1984

Isolation of Eyach virus (Reoviridae, Colorado tick fever group) from Ixodes ricinus and I. ventalloi ticks in France.

During the spring of 1981, two strains of an identical virus were isolated in Mayenne, France, from Ixodes ricinus L. and Ixodes ventalloi Gil Collado, parasiting a wild rabbit (Oryctolagus cuniculus L.). Virological and serological results indicated that these strains belong to the Colorado tick fever serogroup and are indistinguishable from Eyach virus, a tick-borne virus previously described from West Germany. Study of dsRNA PAGE profiles confirmed these conclusions. The morphology and morphogenesis of French isolates were studied in infected suckling mouse brains showing some peculiar features previously described for Colorado tick fever virus. The importance of the isolation of Eyach virus in France is discussed.

Animals↗
PubMed1984

Characterization of the Changuinola serogroup viruses (Reoviridae: Orbivirus).

The antigenic, biological, and chemical properties of 24 selected Changuinola serogroup viruses were examined. The viruses tested were chloroform-resistant, and they were lethal to newborn hamsters after intracerebral inoculation. The prototype Changuinola virus strain (BT-436) replicated in mosquito and sandfly cell cultures. In complement-fixation tests, the viruses were broadly cross-reacting and indistinguishable; but by neutralization test at least 12 distinct serotypes were identified, and by PAGE of double-stranded RNA 22 distinct profiles were found. These data suggest that the Changuinola serogroup may be comprised of a large number of genetically different viruses. A brief review of the natural history of Changuinola serogroup viruses is also given.

Animals↗
PubMed1984

Characterization of the Palyam serogroup viruses (Reoviridae: Orbivirus).

31 Palyam serogroup viruses were examined by complement-fixation and plaque-reduction neutralization tests and by PAGE of the segmented, double-stranded (ds) RNA genome. Although the viruses were indistinguishable by complement-fixation tests, 10 distinct virus serotypes were identified by plaque-reduction neutralization methods. Palyam group viruses which were distinct by the neutralization test had unique dsRNA profiles, whereas those agents which were indistinct by the neutralization test had identical dsRNA profiles. 20 isolations of 3 Palyam serotypes were made from bovines and Culicoides midges in Australia over a 9-year period. When the genome of these isolates was examined electrophoretically, the dsRNA profiles of virus isolates within a given serotype were identical.

Animals↗
PubMed1983

Rapid methods for comparing the double-stranded RNA genome profiles of bluetongue virus.

Various double-stranded RNA extraction procedures, gel electrophoresis systems, and methods to detect the RNA bands in the gel were investigated to find the most rapid methods to obtain the genome profiles of bluetongue virus in small volumes (1-25 ml) of infected cell culture fluids. Rapid double-stranded RNA extraction procedures coupled with staining the acrylamide gel slabs with ethidium bromide or silver nitrate resulted in well-defined genome profiles from bluetongue virus infected cell cultures in 6-48 h. Radioactive labelling of viral RNA with 32P was time consuming, cumbersome and expensive. These techniques detect less than 0.5 micrograms of double-stranded RNA which can be obtained from one 1-ml well of a 24-well cluster plate of bluetongue virus infected cell monolayers. The methods were therefore suitable for rapid comparisons of the electropherotypes of multiple virus isolates.

Bluetongue virus↗
PubMed1983

Detection of antibody to epizootic diarrhea of infant mice (EDIM) virus.

Cultured mouse liver cells containing either eipzootic diarrhea of infant mice viral antigen or Nebraska calf diarrhea vaccine virus antigen were equally effective for detecting serum antibody to epizootic diarrhea of infant mice virus by immunofluorescence. The presence of rotavirus in infant mouse intestinal suspensions used as cell culture inocula was confirmed by polyacrylamide gel electrophoresis of the double-stranded RNA viral genome. When the immunofluorescence assay was tested in a limited comparison with an enzyme-linked immunosorbent assay using simian rotavirus SA 11 viral antigen, the fluorescence test was specific but less sensitive than the enzyme-linked immunosorbent assay.

Animals↗
PubMed1982

Characterization of invertebrate cell lines. IV. Isozyme analyses of dipteran and acarine cell lines.

Cell extracts of five mosquito cell lines and a tick cell line were examined for four cellular isozymes using a cellulose-acetate electrophoretic technique. This method distinguished the cell lines that were derived from the different species. Intraspecies distinctions were not made using the cell lines tested; the significance of this finding is discussed. The usefulness of this technique in identifying a potentially mislabeled cell line was demonstrated.

Aedes↗
PubMed1982

Electrophoretic comparison of the genomes of North American bluetongue viruses, one Australian bluetongue virus, and three other related orbiviruses.

The genomes of U.S. bluetongue viruses, an Australian bluetongue virus, and three other related orbiviruses were analyzed by polyacrylamide gel electrophoresis. The genomes were comprised of ten segments of double-stranded (ds) RNA. Estimates of the molecular weights of the dsRNA segments revealed that the U.S. bluetongue serotypes were remarkably similar. Although the dsRNA profiles of the viruses exhibited common segments, each virus had a distinct dsRNA profile. The usefulness of the genome analysis as a diagnostic tool for identification and for epidemiologic studies is discussed.

Arboviruses↗
PubMed1979

Plaque assay of baculoviruses employing an agarose-nutrient overlay.

Four baculoviruses produced visible plaques in the Spodoptera frugiperda cell line when cell monolayers were infected and overlayed with a simplified, agarose-nutrient formulation. Macroscopic plaques were first detected 4 days postinoculation, and by 10 days plaques ranging from 0.5 to 3 mm in diameter were seen. Dose-response experiments indicated that a single particle initiated the formation of a plaque, because a linear response was demonstrated with increased dosage.

Animals↗
PubMed1975

Replication of nuclear polyhedrosis virus in a continuous cell culture of Spodoptera frugiperda: microscopy study of the sequence of events of the virus infection.

A microscopy study of the sequence of morphogenic events of Spodoptera frugiperda nuclear polyhedrosis virus infection of S. frugiperda cells is presented which orders the sequence of replication and establishes the time scale within which the events occur. The virus entered the cell by 1 h postinfection and was uncoated. The eclipse period was 9 h and the latent period was 12 h. Polyhedron formation was detected by 18 h postinfection and continued until the deposition of the polyhedron membrane was completed by 48 h postinfection. Aberrant morphogenic characteristics of virus repeatedly passaged in the cell culture were also recorded. Adsorption, envelope morphogenesis, and release mechanisms are discussed in light of other data on in vivo and in vitro baculovirus infections.

Adsorption↗
PubMed1974

Replication of a nuclear polyhedrosis virus in a continuous cell culture of Spodoptera frugiperda: purification, assay of infectivity, and growth characteristics of the virus.

Nonoccluded virus, polyhedra, and occluded virus were purified from a continuous cell culture of Spodopera frugiperda infected with nuclear polyhedrosis virus. The optimal temperature for the replication and lateral transmission of infectivity for the nuclear polyhedrosis viruses (NPV) in cell culture was 27 C. End-point dilution and plaque assay procedures for the measurement of infectivity are described and compared. Dose-response data demonstrated that a single particle could initiate an infection, and the validity of the relationship of 0.7 PFU per mean tissue culture infective dose (TCID(5 0)) further substantiated the accuracy of these infectivity assays. Particle-infectious unit calculations gave a ratio of 62 to 310 nonoccluded virus particles TCID(5 0). Growth cycle and lateral transmission experiments indicated that infectious material was released from cells 12 h postinfection (p.i.) and approached a maximal titer 4 days p.i. The number of polyhedra, nonoccluded virions, and TCID(5 0) produced per cell was also presented. Typical yields of NPV produced per liter flask suggested that insect cell culture systems represent a feasible means by which the replication of these viruses could be investigated.

Cell Line↗
PubMed1973

Rhabdoviruses.

Explore the source record for details and available documents.

Antigens, Viral↗
PubMed1970

Mycoplasma pneumoniae and Mycoplasma salivarium: electron microscopy of colony growth in agar.

Colonies of Mycoplasma pneumoniae and Mycoplasma salivarium grown in PPLO agar were examined by light and electron microscopy. The main objective of the investigation was to attempt in situ fixation and minimize tonic changes in the organisms. Microscopy revealed that both organisms grew both in and upon the agar. The agar and surface growths of M. pneumoniae exhibited similar profiles, whereas those of M. salivarium differed strikingly. Both organisms are highly pleomorphic, but their matrix was denser and appeared more intact than in previously reported profiles. Cells which resemble the commonly reported mycoplasma were occasionally observed. The significance of these discrepant profiles remains unanswered. It is suggested that they may represent aged or osmotically damaged cells.

Agar↗
PubMedDate not supplied

Comparative genome analysis of the yellow fever mosquito Aedes aegypti with Drosophila melanogaster and the malaria vector mosquito Anopheles gambiae.

An in silico comparative genomics approach was used to identify putative orthologs to genetically mapped genes from the mosquito, Aedes aegypti, in the Drosophila melanogaster and Anopheles gambiae genome databases. Comparative chromosome positions of 73 D. melanogaster orthologs indicated significant deviations from a random distribution across each of the five A. aegypti chromosomal regions, suggesting that some ancestral chromosome elements have been conserved. However, the two genomes also reflect extensive reshuffling within and between chromosomal regions. Comparative chromosome positions of A. gambiae orthologs indicate unequivocally that A. aegypti chromosome regions share extensive homology to the five A. gambiae chromosome arms. Whole-arm or near-whole-arm homology was contradicted with only two genes among the 75 A. aegypti genes for which orthologs to A. gambiae were identified. The two genomes contain large conserved chromosome segments that generally correspond to break/fusion events and a reciprocal translocation with extensive paracentric inversions evident within. Only very tightly linked genes are likely to retain conserved linear orders within chromosome segments. The D. melanogaster and A. gambiae genome databases therefore offer limited potential for comparative positional gene determinations among even closely related dipterans, indicating the necessity for additional genome sequencing projects with other dipteran species.

Aedes↗