The 1918 “Spanish Flu” pandemic was cause by an Influenza A virus that infected 500 million people and nearly 50 million people died. Influenza viruses utilize a RNA-Dependant RNA Polymerase (RdRp) complex, composed of the PA, PB1 and PB2 proteins along with the viral nucleoprotein (NP) to mediate viral transcription and replication. The 1918 PB1 gene has been linked to increased virulence in mice and ferrets. We have investigated the role of PB1 in the transcription and replication of the 1918 virus and its relation to pathogenicity by comparing its RdRp to the RdRp of a low virulence conventional H1N1 human virus isolate, A/Canada/RV733/2007 (RV733). Contrary to previous studies, our dual-luciferase reporter assay revealed the 1918 RdRp had lower transcriptional activity than the RV733 RdRp in vitro. The 1918 NP seems to be the key determinant for the difference in transcriptional activity of the 1918 and RV733 RdRp complexes. The 1918 PB1 in the RV733 RdRp maintained high reporter expression while the RV733 PB1 in the 1918 RdRp abolished reporter expression. 1918/RV733 chimeric PB1 proteins were also generated and evaluated with the reporter assay. Recombinant RV733/1918 viruses were generated by reverse genetics and we determined that PB1 is a key determinant of the high growth phenotype of the 1918 virus, but only a minor contributor to pathogenicity. A novel role for the 1918 NP in the high growth phenotype and pathogenicity of the 1918 virus is also described.

The cytoskeleton plays an important role in trafficking proteins and other macromolecular moieties throughout the cell. Viruses have been thought to depend heavily on the cytoskeleton for their replication cycles. However, studies, including one in our lab, found that some viruses are not inhibited by anti-microtubule drugs. This study was undertaken to evaluate the replication of viruses from several families in the presence of cytoskeleton-inhibiting drugs and to examine the intracellular localization of the proteins of one of these viruses, Sindbis virus, to test the hypothesis that alternate pathways are used if the cytoskeleton is inhibited. We found that Sindbis virus (Togaviridae, positive-strand RNA), vesicular stomatitis virus (Rhabdoviridae, negative-strand RNA), and Herpes simplex virus 1 (Herpesviridae, DNA virus) were not inhibited by these drugs, contrary to expectation. Differences in the localization of the Sindbis virus were observed, suggesting the existence of alternate pathways for intracellular transport.

Hepatitis B virus genotype G (HBV/G) is a unique genotype of HBV which contains a 36-nucleotide insertion in the Core gene as well as 2 mutations that lead to stop codons in the Pre-Core coding region. Chronic infection with HBV/G is not known to occur without a co-infecting HBV genotype, suggesting that it is defective on its own. This study aims to look at the replication capacity of HBV/G, HBV/A, and HBV/A/G recombinant strains circulating in Canada and to determine the relationship between co-infecting strains. Four full-length HBV genomes were isolated from 2 different patients and transiently transfected into the HepG2 human hepatoma cell line for phenotypic analysis of each strain. HBV/G, HBV/A and HBV/A/G recombinant strains were isolated from Patient 1, while a different HBV/A/G recombinant strain was isolated from Patient 2. HBV replication capacity was measured using a quantitative real time PCR assay. Markers of replication, such as secreted HBsAg and HBeAg, intracellular core particles and replicative DNA intermediates were measured by ELISA, Western blot and Southern blot, respectively. HBV/G demonstrated a higher replicative capability, relative to its co-infecting strains, while both HBV/A/G strains had levels of secreted HBV DNA greater than HBV/A alone, suggesting a modulating effect due to recombination. Replication marker levels revealed possible reasons for a co-infection requirement during HBV/G infection such as HBeAg for chronicity. These observations demonstrate the potential interactions of HBV/G with its co-infecting HBV genotype and provide the first reported phenotypic analysis of a HBV recombinant.

Thesis (Ph. D.)--University of Adelaide, Dept. Plant Science, 1997. / Errata pasted on front fly-leaf. Includes bibliographical references (leaves 139-173).

Thesis (Ph.D)--University of Wollongong, 2003. / Typescript. Includes bibliographical references: leaf 210-234.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 82-102). Also available in electronic version.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 154-168). Also available in electronic version.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [137]-147).

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 96-111). Also available in electronic version. Access restricted to campus users.

Thesis (M.S.)--Brigham Young University. Dept. of Microbiology & Molecular Biology, 2004. / Includes bibliographical references (p. 58-61).