The Analysis Of HaSNPV ODV Infection Hz-AM1 Cells In Vitro

Nucleopolyhedrovirus (NPV) (family Baculoviridae) is an enveloped double-stranded DNA virus that infects only arthropod hosts, primarily lepidopteran insect larval. NPVs are unusual among viruses because they produce two phenotypes: occlusion derived virus (ODV) and budded virus (BV). BV spreads infection from cell to cells to cells within the host, and ODV transmits infection between hosts. In this thesis, we report that Helicoverpa armigera nucleopolyhedrovirus (HaSNPV) ODV can infect Hz-AM1 cells in vitro. The infectivity is dependent on pH. The highest infectivity is about at pH 8.0, and it will decrease when pH>8.0. It has been reported that p74, pif-1, pif-2 and pif-3 are essential for oral infection of baculovirus. We demonstrated that the HaSNPV oral infection related genes, p74, pif-1, pif-2 and pif-3 are also involved in ODV infection in vitro. In addition, we constructed a recombinant HaSNPV containing the hsp70/lacZ reporter cassette (vHa/lacZ) to elucidate pathogenesis in depth, especially the pathogenesis at midgut and tracheal system.In chapter one, an overview outlines the character of baculovirus, major on the mechanism of baculoviruses invading into insects cells as well as the function of the per os infectivity factor (pif). We also introduce the basic concept of gene therapy and the viral vectors including baculoviral vector for gene therapy. In chapter two, we describe the analysis of ODVs of HaSNPV infect Hz-AM1 cells in vitro. We demonstrate ODVs could not only infect host larvae through midgut in vivo but also Hz-AM1 cells in vitro resulting in infection. And the infectivity is influenced by the pH. In addition, we demonstrate the importance of the pif genes to ODV infection in vitro by virus neutralization. In chapter three, we describe the construction of the recombinant virus (vHa/lacZ), and primarily elucidate pathogenesis, especially the pathogenesis at midgut and tracheal system.