| Chapter one is a general introduction of knowledge on baculovirus, including the overview of the research history of baculovirus, the introduction of the major envelope membrane (glyco-) proteins and apoptosis inhibiting factors both presenting in group I and group II Nucleopolyhedroviruses. The fundamental of biological characterization and infection processes of baculoviruses are indicated. The principle of mechanism of Real-Time Quantitative PCR is introduced. The overview of studies in this thesis is also included.A novel method available for determining virus infectivity and its genomic DNA copies was set up in Chapter two. A previously constructed recombinant Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearNPV) vHa+gp64+egfp, which expressed GP64 from AcMNPV, was found with significantly increased infectivity than its parental virus vHa+egfp. In this study, quantitative PCR with TaqMan probe specific to lef-8 gene was used to determine genome DNA copies of the budded virus and compared to viral titers to investigate the infectivity of progeny viruses in these viruses. The results showed that for vHa+egfp, one TCID50 unit tested by end point dilution assay was equivalent to 103 copies of viral genome DNA. For vHa+gp64+egfp, however, one TCID50 unit was equivalent to 102 copies of viral genome DNA. Based on the titer determined by quantitative PCR, we compared the growth curve of vHa+gp64+egfp with vHa+egfp and the result showed that the supernatant of vHa+gp64+egfp was ten times more infectious than vHa+egfp when propagated in the HzAM1 cells. To determine the quantity of recombinant virus entered into cells, we detected the genome DNA copies of recombinant virus per infected cell at the early stage of the infections. The genome DNA copies in one HzAM1 cell infected with vHa+gp64+egfp were ten times higher than that of vHa+egfp when the same DNA copies were...
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