No description available.

No description available.

Because of the varied opinions and findings concerning the effect of cellular antimetabolites on the replication of both RNA and DNA-containing animal viruses, this project was undertaken to observe the effects of antimetabolites on Newcastle disease and vaccinia viruses: an RNA and a DNA virus respectively. The compounds chosen were the pyrimidine analogues 5-fltrorouracil and 5-iodo-deoxyuridine, and thioguanine, a purine antimetabolite. These compounds were chosen because they have already been shown to have growth inhibiting properties in other systems. Inhibition of virus replication was attempted rather than protection of cells, although some effort was made at the outset to determine the tolerance of the 10 - 12 day old chick embryo for the antimetabolites used in this study. The tolerance of the 10 - 12 day old chick was determined by inoculating the yolk sac of the developing embryo with the analogues and noting the survival time. The maximal concentration of the analogue which allowed 3 out of 4 embryos to survive for 48 hours at 37°c was the dose employed in the tests. Inoculation of the embryos with the virus was via the allantoic cavity or the chorio-allantoic membrane. Administration of the antimetabolite was made via the yolk sac either immediately after virus inoculation or if- hours later. After incubation for 36 - 48 hours at 37°C, the allantoic fluid and homogenized chorio-allantoic membranes were assayed to determine whether, there was any decrease in the production of virus-specific material in the presence of the antimetabolites. Tissue cultures of chick fibroblast cells infected with vaccinia virus were treated with antimetabolite and observed for noticeable changes. Nucleic acid analogues appear to vary in their inhibitory effects on different viruses. The enzymatic mechanism of the inhibitions seems to differ in different organisms. Antimetabolites may inhibit replication of DNA viruses and not of RNA viruses, or they may vary in degree and manner of inhibition among the DNA or RNA containing viruses themselves. 5-Fluorouracil was found to inhibit partially the replication of vaccinia virus in the chick embryo. The antimetabolite appeared to have no significant effect on the replication of Newcastle Disease virus. There were no observable differences in the titers of either virus harvested from thioguanine treated embryos as compared with-untreated embryos. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

No description available.

Call number: LD2668 .T4 1958 M32

Digitized by Kansas Correctional Industries

The characteristic trait of the Borna disease virus is that it is a complicated single negative stranded RNA virus that is capable of infecting a wide array of mammalian species including human beings. It has been implicated in a diverse variety of human neuropsychiatric diseases. The infection capability, mechanism of infection and range of protein action of this virus remain to be identified. The purpose of the present study was to determine (1) whether the previous Bornaviridae family classification is indeed accurate as the action of BDV indicates that it is related to other viruses and (2) to estimate the number of synonymous (nucleotide substitution) and non-synonymous (amino acid change) evolutionary mutation rates of proteins (nucleoprotein, phosphoprotein, glycoprotein, matrix protein) exhibited by various Borna disease virus host species and the proteins (nucleoprotein, phosphoprotein, glycoprotein, matrix and X protein) of three Borna disease virus strains. The latter study would give an indication as to which proteins are subjected to positive selection. Phylogenetic methods were used to determine the accuracy of the Bornaviridae classification. Phylogenetic trees obtained through an alignment and analysis of the polymerase protein, which displays a uniquely conserved GDN motif, of various RNA negative single stranded viruses using neighbourhood and parsimony methods enabled comparison with other RNA virus families. A method adapted from Ina, (1995) for estimating the synonymous and non-synonymous evolutionary mutation rate was applied to various BDV proteins in order to provide more information on inter (host virus) and intra (virus) mutation rate. This information in turn was used to create an evolutionary model to clarify the positive and neutral evolutionary trend of the inter- and intra-virus proteins examined, which may help clarify and enhance the lack of current knowledge relating to species infection and the epidemiological nature of the virus. The results obtained by the polymerase alignment analysis indicates the presence of two newly discovered BDV motifs, v and vi, confirmed by three diverse alignment programmes. An analysis of the alignment of BDV proteins indicated that the BDV nucleoprotein nuclear localization signal aligns the BDV nucleoprotein between motifs IV and vi of the BDV polymerase. The results obtained by the phylogenetic analysis indicate that the Rabies virus and the Vesicular stomatitis virus are the most closely related animal viruses to BDV, whereas the Rice transitory yellowing (unclassified Rhabdovirus) and Sonchus yellow net plant virus are closet to BDV than other animal Rhabdoviridae raising intriguing questions on the evolutionary origins of the Borna disease virus. The phylogenetic analysis indicates that the Borna disease virus does not fall into a separate Bornaviridae family classification, and suggests that BDV may be more appropriately placed into a separate subfamily in the family Rhabdoviridae. The results of the evolutionary analysis indicate considerable diversity between BDV host virus (inter-species) and BDV virus (intra-species) protein sequences. In the host virus sequence comparison analysis all of the proteins examined displayed a high pattern of non random evolution, which is in contrast to the intra species comparison in which only three proteins; the BDV glycoprotein, nucleoprotein and X protein; displayed a non random pattern of evolution. The positive selection effect displayed by the inter-species (host) proteins may be attributed to antigenic variation displayed by the inter-species sequences and a super infection hypothesis, which indicates that positive selection on host variants could arise during the course of an infection as a result of specific immune responses. The positive and neutral selection trend of the proteins displayed by the intra-species (virus) sequences may be a result of a pattern of nucleotide substitution that is physio-chemically conservative. Conservation may be evident in volume, polarity, hydrophilicity, or molecular weight of amino acids of the proteins. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

Indiana University-Purdue University Indianapolis (IUPUI) / Vaccinia virus (VV) is the prototypical member of the orthopoxvirus genus of the Poxviridae family, and is currently being evaluated as a vector for vaccine development and cancer cell-targeting therapy. Despite the importance of studying poxvirus effects on the human immune system, reports of the direct interactions between poxviruses and primary human leukocytes (PHLs) are limited. We studied the specific molecular events that determine the VV tropism for major PHL subsets including monocytes, B cells, neutrophils, NK cells, and T cells. We found that VV exhibited an extremely strong bias towards binding and infecting monocytes among PHLs. VV binding strongly co-localized with lipid rafts on the surface of these cell types, even when lipid rafts were relocated to the cell uropods upon cell polarization. In humans, monocytic and professional antigen-presenting cells (APCs) have so far only been reported to exhibit abortive infections with VV. We found that monocyte-derived macrophages (MDMs), including granulocyte macrophage colony-stimulating factor (GM-CSF)-polarized M1 and macrophage colony-stimulating factor (M-CSF)-polarized M2, were permissive to VV replication. The majority of virions produced in MDMs were extracellular enveloped virions (EEV). Visualization of infected MDMs revealed the formation of VV factories, actin tails, virion-associated branching structures and cell linkages, indicating that infected MDMs are able to initiate de novo synthesis of viral DNA and promote virus release. Classical activation of MDMs by LPS plus IFN-γ stimulation caused no effect on VV replication, whereas alternative activation of MDMs by IL-10 or LPS plus IL-1β treatment significantly decreased VV production. The IL-10-mediated suppression of VV replication was largely due to STAT3 activation, as a STAT3 inhibitor restored virus production to levels observed without IL-10 stimulation. In conclusion, our data indicate that PHL subsets express and share VV protein receptors enriched in lipid rafts. We also demonstrate that primary human macrophages are permissive to VV replication. After infection, MDMs produced EEV for long-range dissemination and also form structures associated with virions which may contribute to cell-cell spread.