Baculoviruses are a family of mostly insect-specific viruses with relatively complex infection pathology. The baculovirus genome encodes between 89-181 genes, that are regulated by a complex temporal cascade of gene expression. Although baculoviruses pathogenic to lepidopteran hosts are well characterized, relatively little is known about non-lepidopteran baculoviruses. This thesis provides the genome sequence of a baculovirus pathogenic to the balsam fir sawfly (order: Hymenoptera), the Neodiprion abietis nucleopolyhedrovirus (NeabNPV). Our analyses of the NeabPNV genome indicated that the regulation of NeabNPV early genes by immediate early transactivators may differ from the lepidopteran baculovirus model. Also, through genome sequence analysis, we propose a model for the evolution of sawfly baculoviruses that is mediated by interspersed genome repeats. By selecting key genes transcribed at distinct time points during baculovirus infection as well as quantifying viral DNA in the tissues of infected host larvae, we mapped the progression of NeabNPV infection in vivo. Based on the temporal scale of viral infection, we were able to show that two putative zinc-finger proteins, neab24 and neab52 are expressed in the immediate early and early stages of infection. The hypothesis that the mechanism of early gene regulation in non-lepidopteran baculovirus differs from that of lepidopteran baculoviruses prompted us to investigate promoter elements of 30 baculovirus genomes sequenced to date, in silica. This analysis revealed some sequence motifs may represent promoter elements in a wide range of baculoviruses, and that there may be differences in regulation of transcription between genes of the same temporal class in different baculovirus species.

This work describes the pathology of the baculovirus native to the balsam fir sawfly, Neodiprion abieris nucleopolyhedrovirus (NeabNPV), both in vitro and in vivo. In vitro techniques were initially established through the characterization of Lambdina fiscellaria lugubrosa NPV (LafiNPV-W) in Malacosoma disstria (forest tent caterpillar) and Choristoneura fumiferana (eastern spruce budworm) tissue cultures. The results showed that host cell selection is important for the accurate characterization of viral pathology M. disstria cells infected by LafiNPV-W supported a biased production of extracellular viral progeny and aberrant LafiNPV-W occlusion bodies. C. fumiferana cells, on the other hand, supported production of both the extracellular and occluded phenotypes. The pathology of NeabNPV was studied in vitro using the C. fumiferana cell line and three cell lines derived from the closely related red-headed pine saw-fly, N lecontei. All three sawfly cell lines were non-permissive to NeabNPV, while C. fumiferana was semipermissive and enabled preliminary characterization of early pathology, including early viral gene transcription. Due to only partial success in characterizing NeabNPV infection in vitro, pathology was examined within the native larval host, N. abietis. The first step in characterizing NeabNPV infection in vivo was to define the morphology and ultrastructure of the gut of uninfected N. abietis larvae. The sawfly alimentary canal consisted of cuticle lined foregut and hindgut, which adjoined to an elongated midgut. The epithelial tissue of the midgut was composed of regenerative and digestive columnar cells; the latter possessed a complex ultrastructure that reflexed the cells function in nutrient absorption and digestive enzyme secretion. NeabNPV pathology was only detected in the midgut epithelial cells. A time course of NeabNPV infection enabled the identification of several key cytopathic effects and the correlation of gene expression with specific phases of viral infection. These analyses revealed both differences and similarities between the process of infection and pathology induced by NeabNPV and lepidopteran NPVs and may serve as a different model for baculovirus infection of nonlepidopteran.

Mémoire(M. Ress. Renouv.)--Université du Québec à Chicoutimi, 1997. / Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Ress.Renouv.)--Université du Québec à Chicoutimi, 1997. / Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Ress.Renouv.)--Université du Québec à Chicoutimi, 1999. / Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Ress.Renouv)--Université du Québec à Chicoutimi, 1999. / Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Ress.Renouv.)--Université du Québec à Chicoutimi, 2001. / Document électronique également accessible en format PDF. CaQCU

Thèse (D.Sc.Env.) -- Université du Québec à Chicoutimi, 2003. / Bibliogr.: f. 110-115. Document électronique également accessible en format PDF. CaQCU

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Mémoire (M.Ress.Renouv.)-- Université du Québec à Chicoutimi, 1994. / Résumé disponible sur Internet. CaQCU Document électronique également accessible en format PDF. CaQCU