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M A McCrae

Publications and source records attributed to M A McCrae.

At least 55 records · Page 3Linked to original sources
PubMed1986

Group C rotaviruses in humans.

Atypical rotaviruses obtained from human feces from Australia, Brazil, and the United Kingdom were shown by a combination of techniques--immunoelectron microscopy, immunofluorescence, genome profile analysis, terminal fingerprint analysis of genome segments, and dot-blot hybridization--to be related to group C porcine rotaviruses. The prevalence of antibody to group C rotaviruses was found to be low in human sera and immunoglobulin pools from six countries. No signs of infection were obtained when one of the human viruses was inoculated into gnotobiotic piglets. We conclude that the atypical human viruses are the first examples of group C rotaviruses in humans.

Animals↗
PubMed1985

Stability and movement of mRNAs and their encoded proteins in Xenopus oocytes.

The stability and movement of several polyadenylated (poly A+) and nonpolyadenylated (poly A-) mRNAs in Xenopus oocytes have been examined. At least 50% of the poly A+ mRNA molecules (9S rabbit globin mRNA, chicken ovalbumin, and lysozyme) were stable in oocytes over a 48-h period, irrespective of the amount injected. About 50% of injected poly A- reovirus mRNAs was degraded within the first 24 h of injection, irrespective of the amount injected, although no further degradation was observed over an additional 24 h. The movement of all poly A+ mRNAs injected at either the animal or vegetal pole of the oocyte was very slow. Little movement of RNA from the animal half to the vegetal half was observed even 48 h after injection. In contrast, similar amounts of mRNA were present in both halves 48 h after vegetal pole injection. Similar results were obtained after injection of poly A- reovirus mRNAs. The movement of the proteins encoded by the poly A+ mRNAs was studied in the 6-h period after injection when little mRNA movement had occurred. 85% of the globin synthesized accumulated in the animal half irrespective of injection site. The movement of the sequestered secretory proteins ovalbumin and lysozyme in the same oocytes as globin was much slower; very little lysozyme appeared in the half of the oocyte opposite the site of injection.

Animals↗
PubMed1984

A rapid screening assay for detecting individual RNA species in field isolates of rotaviruses.

A method is described that allows the rapid screening of field isolates of rotavirus for the detection of specific viral RNA segments. Cloned cDNA copies of viral genomic RNAs are employed for detection in the assay which makes use of the dot-hybridization technique of Thomas (1980). The assay developed was shown to be sufficiently sensitive and specific to allow the genetic composition of virions to be determined over a wide range of concentrations. The feasibility of using the method developed for both the analysis of genetic reassortants prepared in vitro and for screening field isolates to detect putative genome reassortment events is demonstrated.

DNA, Recombinant↗
PubMed1984

The molecular biology of rotaviruses. VII. Detailed structural analysis of gene 10 of bovine rotavirus.

cDNA cloning and nucleotide sequence analysis have allowed detailed structural studies on RNA segment 10 of the U.K. bovine rotavirus to be undertaken. The complete sequence of 751 nucleotides was determined and found to contain only a single long open reading frame capable of coding for a protein of 175 amino acids. The gene has an unusually long 3' untranslated region of 184 nucleotides or some 24.5% of the total sequence, whose start was confirmed by analysing the carboxyterminal amino acid of the gene 10 product, the glycoprotein VP10c. Analysis of purified virions radio-labelled with [3H]glucosamine and [3H]mannose showed that VP10c is not a detectable component of the virus particle. The two potential glycosylation sites were found to be very close to the amino terminus of the putative translation product, strongly suggesting that the glycoprotein VP10c does not contain a cleavable signal sequence.

Base Sequence↗
PubMed1984

The genomes of rotaviruses isolated from chronically infected immunodeficient children.

Abnormal RNA migration profiles were found in numerous rotavirus samples from two chronically infected children suffering from severe combined immunodeficiency. In both cases additional bands consisting of dsRNA were found migrating between RNA segments 1 and 7, and in one case RNA segment 11 was lost from the profile. Hybridization studies using segment-specific cloned cDNA probes indicated that some of the additional bands had sequence homologies with normal rotavirus dsRNA segments. In most cases these sequences were derived from genome segments of lower molecular weight by the formation of covalently linked concatemers.

Child, Preschool↗
PubMed1983

Molecular biology of rotaviruses. V. Terminal structure of viral RNA species.

The terminal structure of rotavirus genomic ds RNA and in vitro transcribed mRNA was investigated using S1 nuclease digestion and 3' terminal sequence analysis. S1 nuclease analysis indicated that viral mRNA was not a truncated copy of the genome RNA at its 5' end. The 3' terminal sequence analysis of genomic plus strands and mRNA showed that they were coterminal indicating that in vitro transcribed mRNA is a full length copy of the genomic template. The sequence analysis performed on isolated viral RNA species plus strands revealed a completely conserved 3' terminal octanucleotide 5'-AUGUGACC-3' present in both UK tissue culture adapted bovine rotavirus and a human rotavirus isolate. Sequencing of isolated genomic minus strands again revealed a completely conserved 3' terminal sequence of approximately the same length as that seen for the viral plus strands.

Base Sequence↗
PubMed1983

Molecular characterization of rotaviruses with distinct group antigens.

Comparative serological and nucleic acid studies were carried out on rotavirus isolates, with and without the original group antigen. Indirect immunofluorescence allowed the atypical isolates to be divided into two groups each with its own distinct group antigen hence giving a total of at least three distinct rotavirus groups. Genome profile analysis of the atypical isolates again divided them into two groups which corresponded with those obtained by immunofluorescence and within which the overall pattern of genome segments was similar. A more rigorous examination of the degree of difference between the three virus groups was carried out using single-dimension terminal fingerprint analysis. This indicated that the viruses in the three groups did not carry any genome segments in common with each other. Therefore, experimental criteria have been established which allow the division of rotaviruses into three groups. Analysis of further atypical isolates, as they become available, will establish whether the division of rotaviruses into a number of separate groups, of the type seen in influenza virus, is justified.

Animals↗
PubMed1983

The molecular biology of rotaviruses. VI. RNA species-specific terminal conservation in rotaviruses.

The use of T1 RNase fingerprinting of terminally labelled genomic double-stranded RNA species from various rotavirus isolates, to analyse the near terminal G-residue positions, has revealed an RNA species-specific fingerprint pattern covering approximately 40 nucleotides at the termini. These RNA species-specific terminal fingerprint patterns were found to be conserved in both rotavirus RNAs isolated from various animal species, and in isolates from a single animal species where gross divergence of internal RNA sequence for a particular RNA species was evident. This conservation of near terminal G-residue positions suggests that, internal to the short regions of absolute terminal sequence conservation that we have previously shown to be present on all rotavirus RNA species, there is a region of conserved sequence which is specific for a particular RNA species.

Animals↗
PubMed1982

Characterization of an antigenically distinct porcine rotavirus.

A porcine virus with rotavirus morphology, which was antigenically unrelated to previously described rotaviruses, is described. Particles with an outer capsid layer measured 75 nm and those lacking the outer layer were 63 nm in diameter. Particles which resembled cores were also identified. The virus was shown to be antigenically distinct from other rotaviruses as judged by immunofluorescence and immune electron microscopy, and it failed to protect piglets from challenge with porcine rotavirus. Analysis of the genome indicated that it was composed of 11 segments of double-stranded RNA with the same overall size range as other rotaviruses but with an unusual segment pattern.

Animals↗
PubMed1982

Structural analysis of electrophoretic variation in the genome profiles of rotavirus field isolates.

Detailed structural studies were undertaken on five isolates of bovine rotavirus which showed variability in the migration patterns of their genome segments on electrophoresis in polyacrylamide gels. The individual genome segments of each isolate were characterized by partial digestion of terminally radiolabeled RNA with a base-specific nuclease. This analysis showed that whereas mobility variations were always associated with detectable changes in nucleotide sequence, sequence changes at least as great as those found in segments showing electrophoretic mobility variations were also detected in segments showing no mobility variation. Evidence for the occurrence of genome segment reassortment between viruses in the field was obtained from analyzing the species 11 RNAs from these five isolates. The overall conclusion from these results is that great care is required in the interpretation of simple genome profile analysis of different isolates for epidemiological purposes and that classification of these viruses solely on the basis of genome electropherotype could be misleading.

Animals↗
PubMed1982

Molecular biology of rotaviruses. III. Isolation and characterization of temperature-sensitive mutants of bovine rotavirus.

Twenty-six temperature-sensitive (ts) mutants of United Kingdom tissue culture-adapted bovine rotavirus were isolated and characterized. Fourteen of these mutants were determined to be ts both by efficiency of plating and by virus yield at the nonpermissive temperature of 39.5 degrees C as compared with that at the permissive temperature of 32 degrees C. The remaining mutants were only ts by the criterion of efficiency of plating. High-frequency recombination (gene reassortment) was observed when some pairs of mutants were crossed, and this allowed the classification of the mutants into five separate recombination groups. Groups III and V have prototype ts mutants (ts34 and ts115, respectively) that do not synthesize RNA or polypeptides at 39.5 degrees C. The other groups, I, II, and IV, have prototype mutants (ts17, ts7, and ts6, respectively) that synthesize both RNA and polypeptides at 39.5 degrees C, although ts17 does so only at a reduced level.

Cytopathogenic Effect, Viral↗
PubMed1982

Molecular biology of rotaviruses. IV. Molecular cloning of the bovine rotavirus genome.

A new cloning strategy has been developed for cloning the genomes of double-stranded RNA viruses by using bovine rotavirus as a test system. The major modification adopted was the use of denatured polyadenylated double-stranded RNA as the template for reverse transcriptase. This allowed the two complementary strands of cDNA to be synthesized in a single reaction and removed the need for S1 nuclease digestion to remove the 5' hairpin structure normally generated in cDNA synthesis.

Animals↗
PubMed1981

Stability of non-polyadenylated viral mRNAs injected into frog oocytes.

The naturally non-polyadenylated mRNAs of reovirus were shown to have a half-life in excess of 3 days when injected into Xenopus laevis oocytes. Hybridization analysis and gel electrophoresis showed that all 10 mRNA species had a similar high stability, despite being translated at widely differing rates. We have confirmed previous findings indicating a role for the 5'-terminal cap structure in determining reovirus mRNA stability [Furuichi et al. (1977) Nature (Lond.) 266, 235-239]. The significance of these results in relation to a general role for poly(A) in messenger RNA function is discussed.

Animals↗
PubMed1981

A sensitive method for the production of diagnostic fingerprints of the genome segments of field isolates of rotavirus.

The 3'-terminal labelling procedure for analyzing the genome segment profile of field isolates of rotavirus (Clarke and McCrae, 1981, J. Virol. Methods 2, 203) has been further developed to produce a rapid and sensitive method for generating diagnostic fingerprints from individual species of double-stranded RNA. The fingerprints were obtained by a one-dimensional resolution of overlapping terminally labelled oligonucleotides produced by partial nuclease digestion with a base-specific nuclease. This fingerprinting method should be of great value in characterizing the molecular details of genome segment variation and will facilitate detailed molecular epidemiological studies of this important virus group.

Animals↗