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H G Morrison

Publications and source records attributed to H G Morrison.

28 records · Page 2Linked to original sources
PubMed1991

Genetic relatedness of two new Orbivirus serogroups: Orungo and Lebombo.

Orungo and Lebombo orbivirus isolates were examined for their intra- and intergroup genetic relatedness by blot hybridization and gene reassortment; blot hybridization was also used to examine the relatedness of selected Orungo and Lebombo isolates to known orbiviruses. Among the Orungo isolates, greater than 74% sequence similarity was shown in the majority of their genes. Gene 2 was the most divergent gene, with four unique types identified, and genes 5, 6 and 10 were variant among the isolates. Plaque reduction neutralization tests revealed at least four serotypes, a result which correlated with the hybridization data. Gene reassortment was shown between two representative Orungo isolates. Among the Lebombo isolates, two hybridization types were identified between which gene reassortment was demonstrated. Unique genes were not shown, whereas genes 2, 5 and 10 exhibited minor sequence variability. Geographic distribution correlated with relatedness among the Lebombo isolates, which was not the case among the Orungo isolates. Orungo and Lebombo viruses did not cross-hybridize or reassort their genes in vitro, in intergroup studies. In blot hybridization tests of Orungo and Lebombo isolates with known orbivirus serogroups and ungrouped orbiviruses, no strong cross-hybridization was seen. These results demonstrate that Orungo and Lebombo are distinct from each other and from other orbiviruses, and should therefore be recognized as two new Orbivirus serogroups.

Autoradiography↗
PubMed1989

Protection of guinea pigs from Lassa fever by vaccinia virus recombinants expressing the nucleoprotein or the envelope glycoproteins of Lassa virus.

A recombinant vaccinia virus that expresses the nucleoprotein gene of Lassa virus (Josiah strain) under the control of the P7.5 promoter was constructed using the lacZ coexpression transfer vector pSC11. Southern blot analysis demonstrated that recombination of the sequences inserted within the thymidine kinase gene of the transfer vector into the HindIII J fragment of vaccina virus genomic DNA occurred properly. A 63-kDa protein identical in electrophoretic mobility to authentic Lassa nucleoprotein was observed in recombinant virus-infected cell lysates. The reactivity of vaccinia-expressed Lassa proteins to a panel of monoclonal antibodies representing multiple epitopes on each of the N, G1, and G2 proteins was determined by indirect immunofluorescence. Lassa proteins expressed in recombinant vaccinia virus-infected cells reacted in a manner indistinguishable from that of the proteins expressed in Lassa virus-infected cells, indicating that there are no significant differences between authentic and recombinant virus-expressed proteins. Vaccine efficacy trials in guinea pigs indicated that both the nucleoprotein and the envelope glycoproteins are capable of eliciting a protective immune response against a lethal dose of Lassa virus. Ninety-four percent of the animals vaccinated with V-LSN, 79% vaccinated with V-LSGPC, and 58% vaccinated with both recombinant viruses survived a Lassa virus challenge in which only 14% of unvaccinated animals and 39% of animals vaccinated with the New York Board of Health (NYBH) strain of vaccinia virus survived. The protection resulting from vaccination with the recombinant virus vaccines did not correlate with the levels of prechallenge serum antibodies, suggesting that a cell-mediated immune response is a critical component of protective immunity to Lassa fever.

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

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↗
PubMedDate not supplied

Phylogeny of trichomonads inferred from small-subunit rRNA sequences.

Small subunit (16S-like) ribosomal RNA sequences were obtained from representatives of all four families constituting the order Trichomonadida. Comparative sequence analysis revealed that the Trichomonadida are a monophyletic lineage and a deep branch of the eukaryotic tree. Relative to the early divergent eukaryotic assemblages the branching pattern within the Trichomonadida is very shallow. This pattern suggests the Trichomonadida radiated recently, perhaps in conjunction with their animal hosts. From a morphological perspective the Devescovinidae and Calonymphidae are considered more derived than the Monocercomonadidae and Trichomonadidae. Molecular trees inferred by distance, parsimony and likelihood techniques consistently show the Devescovinidae and Calonymphidae are the earliest diverging lineages within the Trichomonadida, however bootstrap values do not strongly support a particular branching order. In an analysis of all known 16S-like ribosomal RNA sequences, the Trichomonadida share most recent common ancestry with unidentified protists from the hindgut of the termite Reticulitermes flavipes. The position of two putative free-living trichomonads in the tree is indicative of derivation from symbionts rather than direct descent from some free-living ancestral trichomonad.

Animals↗