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D L Knudson

Publications and source records attributed to D L Knudson.

At least 37 records · Page 2Linked to original sources
PubMed1989

Co-circulation of multiple Colorado tick fever virus genotypes.

Colorado tick fever (CTF) virus, family Reoviridae, genus Orbivirus, contains 12 genes distinguishable by polyacrylamide gel electrophoresis (PAGE). Multiple genotypes of CTF virus were isolated at 3 field sites in Colorado in 1985. Five genotypes were found at Campos Cabin, 2 at Drake, and 6 at Rocky Mountain National Park. Virus isolations were made in 1985 from 6 patients with CTF. These isolates were distinct from each other and the field isolates. Although the CTF isolates were different by PAGE profile, the majority of the 12 genes were highly conserved among the 1985 isolates and a Florio isolate (FMA). Only genes 4 and 6 were variant among the 1985 CTF isolates and FMA, and no unique genes were identified. In 1986, a follow-up field survey was done at the Campos Cabin site. Of the 3 CTF PAGE genotypes obtained, 2 exhibited PAGE profiles which were different from the 1985 isolates. One isolate may have resulted from the reassortment of genes from 2 of the isolates circulating at Campos Cabin in 1985.

Animals↗
PubMed1989

Genetic relatedness of the kemerovo serogroup viruses: II. RNA-RNA blot hybridization and gene reassortment in vitro of the Great Island serocomplex.

The majority of the thirty-two Great Island serocomplex isolates examined exhibit distinct dsRNA polyacrylamide gel profiles. Yet, these viruses are closely related by blot hybridization with only two genes showing significant sequence divergence. Gene reassortment was demonstrated between selected pairs of the Great Island serocomplex viruses with two different geographic regions represented. The majority of the reassortant progeny from the cross of selected pairs resulted in progeny with multiple gene-replacements. The ability of these selected isolates to reassort confirms the close taxonomic relationship of the isolates in spite of their geographic distribution.

Electrophoresis, Polyacrylamide Gel↗
PubMed1989

Genetic relatedness of the Kemerovo serogroup viruses: III. RNA-RNA blot hybridization and gene reassortment in vitro of the Chenuda serocomplex.

The dsRNA polyacrylamide gel profiles of five Chenuda serocomplex viruses were distinct. Blot hybridization and gene reassortment in vitro studies demonstrated that the Chenuda serocomplex may be divided into three sets: Chenuda, Huacho, and Mono Lake. Genes were highly conserved among members of each set, whereas genes were not highly conserved between members of different sets. Gene reassortment was demonstrated in intra-set crosses, but inter-set crosses did not yield reassortant progeny. The taxonomic significance of these data to the Chenuda serocomplex is discussed.

Electrophoresis, Polyacrylamide Gel↗
PubMed1988

Intra- and inter-serogroup genetic relatedness of orbiviruses. I. Blot hybridization of viruses of Australian serogroups.

Viruses in the Eubenangee, Wallal and Warrego serogroups of orbiviruses have been isolated primarily in Australia. Several isolates in these three serogroups were examined by gel electrophoresis and blot hybridization of genomic RNA. Conserved and variant genes were identified by the degree of hybridization between cognate genes. The dsRNA profiles of isolates within a serogroup exhibited heterogeneity in polyacrylamide gels, but they were indistinguishable in agarose gels. Isolates within a serogroup generally showed a high level of cross-hybridization in eight segments with cognate segments 2 and 6 exhibiting hybridization signal variants. Although Pata virus has been classified in the Eubenangee serogroup, it was not closely related to other Eubenangee isolates by hybridization. Similarly, Mitchell River virus was not closely related to other members of the Warrego serogroup. The taxonomic status of Pata and Mitchell River viruses should be reviewed, and in the interim they should be placed in the ungrouped set of orbiviruses. Inter-serogroup relatedness was also examined by blot hybridization. Representatives from the Eubenangee, Wallal, Warrego, bluetongue, epizootic haemorrhagic disease and Corriparta serogroups were examined. Several of the serogroups were distantly related, and the low level of relatedness was suggestive of a common ancestry. While many of these serogroups may co-circulate in nature, these data suggest that each serogroup represents a distinct gene pool. The taxonomic significance of these data is discussed.

Animals↗
PubMed1988

Intra- and inter-serogroup genetic relatedness of orbiviruses. II. Blot hybridization and reassortment in vitro of epizootic haemorrhagic disease serogroup, bluetongue type 10 and Pata viruses.

Viruses which belong to the epizootic haemorrhagic disease (EHD), bluetongue and Eubenangee serogroups of orbiviruses exhibit low level cross-reactions in some serological tests. Although Pata virus cross-reacts at low levels with members of the EHD and bluetongue serogroups, it was assigned originally to the Eubenangee serogroup. RNA-RNA blot hybridization data, however, suggest that Pata virus is not a member of the Eubenangee serogroup. In this study, the genetic relatedness of the EHD serogroup viruses, bluetongue virus type 10 (BTV-10) and Pata virus was assessed by RNA-RNA blot hybridization and by gene reassortment experiments in vitro. The five members of the EHD serogroup examined were highly related by reciprocal RNA RNA blot hybridization. Genes 1, 3, 4 and 6 to 9 were highly conserved with three unique types of gene 2, four variant types of gene 5 and two variant types of gene 10. Geographical boundaries could not be correlated with sequence relatedness because viruses isolated from the same locality were distant relatives when compared with another virus isolated on a different continent. The significance of the unique and variant genes is discussed. The EHD isolates, BTV-10 and Pata virus exhibited distinct profiles on agarose and polyacrylamide gel electrophoresis, and they are related distantly as shown by weak hybridization signals in blot hybridization. Gene 2 was a unique gene among the EHD isolates, BTV-10 and Pata virus. One BTV-10 gene hybridized more strongly to gene 9 of the EHD viruses than the other BTV-10 genes, and its role in encoding the cross-reactive antigen is discussed. Intra-serogroup gene reassortment in vitro was demonstrated in the six crosses among EHD serogroup members. In contrast, gene reassortment was not observed in inter-serogroup crosses between EHD 1 and BTV-10, BTV-10 and Pata virus, and between EHD 1 and Pata virus. Correlation of blot hybridization and gene reassortment indicated that viruses must share high sequence conservation in the majority of their genes before genetic interaction is likely. The usefulness of blot hybridization as an indicator of the likelihood of gene reassortment is discussed. These hybridization and gene reassortment data indicated that Pata virus is not a member of the bluetongue or EHD serogroups and that it should be assigned to the ungrouped set of orbiviruses. The hybridization and gene reassortment data suggest that members of the EHD serogroup, BTV-10 and Pata virus represent three distinct gene pools, and the role of reassortment in the generation of genetic diversity is discussed.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Genetic relatedness of the Kemerovo serogroup viruses: I. RNA-RNA blot hybridization and gene reassortment in vitro of the Kemerovo serocomplex.

The dsRNA profiles of the Czechoslovakian and Siberian serotypes of the Kemerovo serocomplex viruses examined were similar in agarose, while their dsRNA profiles were distinct in polyacrylamide gel. Blot hybridization studies of the Kemerovo serocomplex viruses demonstrated that the genes were highly conserved among the members within each type, but not between types. Gene reassortment in vitro was demonstrated among selected pairs of the Kemerovo serocomplex viruses by intra- and inter-typic crosses. The majority of the reassortant progeny from inter-typic crosses were single gene replacements, whereas the majority of the reassortant progeny from intra-typic crosses were multiple gene replacements suggesting that certain gene combinations were restrictive under conditions of the experiment.

Genes, Viral↗
PubMed1987

Conserved homologous regions between two baculovirus DNAs.

Regions of homology on the physical maps of Spodoptera exempta multiple-nucleocapsid nuclear polyhedrosis virus (SeMNPV-25), an Autographa californica MNPV genomic variant, and S. frugiperda (SfMNPV-2) baculovirus DNAs were identified by reciprocal DNA-DNA blot hybridization under conditions of an effective temperature of Tm -25 degrees C. In addition, cloned fragments of the viral genome which contained the homologous regions were used in hybridization experiments to confirm, refine and correlate the regions of the two physical maps. Five homologous regions conserved between the two physical maps were identified. When the stringency of the hybridization was increased (Tm -20 degrees C), only two of the original regions were identified by blot hybridization. One of the two regions contained the polyhedrin gene, and the other region was not associated with any known viral function. The five regions did not overlap with the intragenic homologous sequence (hr1 to hr5) regions on the SeMNPV-25 map or with restriction endonuclease variant (vI to vIV) regions on the SeMNPV-25 and SfMNPV-2 maps. The degree of similarity in the genomic organization of these two baculoviruses is discussed.

Animals↗
PubMed1987

Genetic relatedness of corriparta serogroup viruses.

Eight viruses of the Corriparta serogroup (Reoviridae: Orbivirus) that were known to be heterogeneous on the basis of serology and polyacrylamide gel electrophoresis were examined by reciprocal RNA-RNA blot hybridization of genomic RNA. Conserved and variant genes were identified by the degree of hybridization between cognate genes of different isolates. The eight viruses were divided into three subsets on the basis of the number of shared genes. Four of the viruses, isolated in Australia, formed one subset of related isolates and shared five conserved genes. Another isolate, Acado, was variant in all 10 genes and was considered to be a second subset. The remaining three isolates formed a third subset and shared four conserved genes. Genes 1, 3 and 10 were the most variable among the Corriparta serogroup isolates. Subsets of isolates within a serogroup which are highly related in the majority of the 10 genes and less related to serogroup viruses in another subset have not been reported previously. The phylogenetic relationship of Corriparta serogroup members suggested by the blot hybridization data is not apparent in the current taxonomic classification of these viruses which is based primarily upon serological data. The hybridization data on the Corriparta serogroup viruses are discussed and contrasted with other Orbivirus serogroups which have been examined similarly.

Animals↗
PubMed1987

Genetic relatedness of Colorado tick fever virus isolates by RNA-RNA blot hybridization.

The sequence relatedness of ten isolates of the Colorado tick fever (CTF) serogroup of orbiviruses was examined by RNA-RNA blot hybridization. The 12 dsRNA genome segments of each of the isolates were electrophoresed in a 10% polyacrylamide gel, the segments were transferred electrophoretically to membranes and hybridized to radiolabelled genomic RNA from CTF Florio mouse-adapted strain (CTF FMA) or CTF SS-18. All genome segments of the ten CTF viruses exhibited cross-hybridization signals with either CTF FMA or CTF SS-18, under conditions in which greater than or equal to 74% sequence homology was required to form stable hybrids. Although the dsRNA polyacrylamide gel profiles were unique for each isolate examined, the CTF genes did not exhibit sequence divergence as has been seen among other Orbivirus serogroups. These hybridization analyses suggest that the CTF gene pool is relatively homogeneous which may be a reflection of the lack of multiple serotypes of CTF strains in neutralization tests. Nevertheless, the hybridization signals of segments 4 and 6 were lighter than those of the other genes, indicating that these two genes exhibited the highest degree of sequence variability among these isolates. These data are compared with hybridization data on other Orbivirus serogroups.

Colorado tick fever virus↗
PubMed1986

Genetic relatedness of Palyam serogroup viruses by RNA-RNA blot hybridization.

Cognate genes of members of the Palyam serogroup of orbiviruses have been identified previously, and their relatedness to the prototype virus was determined by blot hybridization of the genome segments of members of the serogroup using Palyam genomic RNA and isolated Palyam RNA segments as probes. In this study, the genetic relatedness of nine Palyam serogroup isolates was determined by reciprocal blot hybridizations of genomic RNA from each virus to the segments of all members of the group. The number and identity of highly related genes varied between isolates. For example. CSIRO Village and Palyam were related in genes 2 and 6, while Bunyip Creek and Vellore were related in genes 2 and 6. However, CSIRO Village and Bunyip Creek were highly related to D'Aguilar in all genes except 2 and 6, suggesting that there may have been genetic reassortment of Palyam serogroup dsRNA segments. Genes 2 and 6 were correlated consistently with serotype specificity. Genes 5, 7 and 9 were highly related among all members of the group. The Indian strains, Palyam and Vellore, were highly related in genes 1, 3 and 8, and they exhibited weak homology to genes 1, 3 and 8 of the Australian and African strains. However, one Indian isolate, Kasba, was more closely related to strains from Africa and Australia than it was to other Indian strains. There was little evidence which indicated that geography was predictive of the genetic relationships of the strains. Thus, immunological pressure may be the most important factor affecting the Palyam serogroup gene pool.

Australia↗
PubMed1985

Sequence relatedness of Palyam virus genes to cognates of the Palyam serogroup viruses by RNA-RNA blot hybridization.

Cognate genes of nine members of the Palyam serogroup of orbiviruses have been identified and their relatedness to the prototype, Palyam virus, has been determined. Viral dsRNA segments were electrophoresed through 10% polyacrylamide gels, transferred to membranes, and hybridized to labeled RNA from Palyam virus under hybridization conditions using 52 degrees, 50% formamide, 5 X SSC. Cognate genes of each virus isolate were identified by hybridizing their genomes to [5'-32P]pCp-labeled, isolated segments from Palyam virus. Single segments from Palyam hybridized to no more than one segment in the other isolates. Nine of the 10 genes exhibited nucleic acid sequence homology between Palyam and seven of the other eight isolates. Gene 2 of Palyam hybridized only with gene 2 of CSIRO Village, and it was correlated with serotype specificity. Since CSIRO Village is the only member of the serogroup which cross-reacts with Palyam in neutralization tests, gene 2 may encode the neutralization antigen. Variation in the intensity of the hybridization signals of the remaining nine genes within a given virus indicated that the number and identity of conserved genes differed between members of the group. Genes 5, 7, and 9 were the most conserved genes for all members of the serogroup, while the levels of relatedness of Palyam genes 1, 3, 4, 8, and 10 to their cognates in the other isolates varied under these hybridization conditions.

Animals↗
PubMed1985

Assessment of sequence relatedness of double-stranded RNA genes by RNA-RNA blot hybridization.

Three well-characterized reovirus serotypes were used to investigate the usefulness of RNA-RNA blot hybridization as a means to assess the genetic relatedness of double-stranded RNA (dsRNA) viruses. [5'-32P]pCp-labeled genomic dsRNAs from reovirus 1, 2 and 3 were used as probes in hybridization experiments in which segments of the three serotypes were separated in 10% polyacrylamide gels and transferred electrophoretically to membranes. Nine of the 10 reovirus genes cross-hybridized between the serotypes. The S1 gene was serotype specific. The L2 gene of reovirus 2 showed a lower level of cross-hybridization with types 1 and 3 when compared to the hybridization signal observed for L2 when types 1 and 3 were hybridized to each other. The data were consistent with previous studies on the relatedness of the three virus serotypes. Since RNA-RNA blot hybridization allows the number and identity of conserved genes to be determined, this approach may prove useful for assessing the genetic relatedness among other viruses in the family Reoviridae.

Base Sequence↗
PubMed1985

Baculovirus (MNPV) genomic variants: characterization of Spodoptera exempta MNPV DNAs and comparison with other Autographa californica MNPV DNAs.

A nuclear polyhedrosis virus (NPV) strain from Spodoptera exempta (SeMNPV-25 baculovirus) is a restriction endonuclease DNA map variant similar to Autographa californica NPV (AcMNPV baculovirus). Fourteen restriction endonuclease variants were identified and isolated from a SeMNPV baculovirus stock with 12 of the variants found at low frequency (less than 3%). The DNA from each variant was compared to the prototype SeMNPV-25 for insertions, deletions and new restriction sites. Regions of variation were defined on the prototype SeMNPV-25 genome, and the nature of the variation within these regions was determined. These data are discussed and compared with the existing data on other variants of AcMNPV. A comparison of the physical maps revealed that all the SeMNPV variants were different from those reported for AcMNPV. Although the SeMNPV variants were distinctive, they were clearly genomic AcMNPV variants. The regions of the baculovirus genomic variation were identified, and three separate mechanisms are suggested for their generation. Five regions (hr1 to hr5) were associated with intragenic homologous viral sequences, five regions (vI to vIII) may be associated with the insertion of DNA sequences of cellular origin, and two regions (pI and pII) were associated with mutations resulting in the addition or loss of a PstI site. Physical maps were generated for SeMNPV variant regions vI, hr2, vII and vIII.

Animals↗
PubMed1984

Physical maps of SfMNPV baculovirus DNA and its genomic variants.

Spodoptera frugiperda MNPV was plaque-purified, and the viral DNA from the plaque-purified isolates was analyzed with restriction endonuclease enzymes. Seven distinct variants were identified when the DNA of the isolates were analyzed by EcoRI and HindIII. The DNAs of the SfMNPV predominant type (prototype) and the variants were mapped with BamHI, BglII, BstEII, EcoRI, HindIII, KpnI, and PstI by multiple enzyme digestion and blot hybridization. The cleavage sites generated by the seven restriction enzymes were ordered, and the sites were assigned map coordinates using a least-squares procedure. Since Autographa californica MNPV-E2 EcoRI fragment I, which contains the polyhedrin gene, hybridized with SfMNPV EcoRI fragment P, the physical map of SfMNPV was oriented with EcoRI P on the left, with site 1 being the EcoRI site between fragments F and P. The calculated genome size was 121.76 kilobase pairs or 80.36 X 10(6) Da. The DNA from each variant was compared to the DNA of the prototype for insertions, deletions, and new restriction sites. Physical maps were generated for each of the variants. The differences between the variant and the prototype were confined to four regions in the SfMNPV genome representing less than 16% of the prototype genome.

Chromosome Deletion↗