Browsing by Author "Wang, Weizhou"

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    Effect of inhaled cationic poly-peptides on respiratory mechanics in the isolated perfused rat lung
    (University of the Western Cape, 1998) Wang, Weizhou; Syce, J. A
    The inhalation route is increasingly being considered as a viable option to deliver protein drugs into the body, but there has been few studies dealing with the safety of this strategy. The results of in vitro studies have shown that proteins, especially cationic proteins, can interfere with pulmonary surfactant and affect its surface tension lowering activity. If such an interaction also occurs in vivo it may lead to the inactivation of endogenous pulmonary surfactant and have profound adverse effect on the respiratory mechanics of the lung. To investigate this contention a suitable model which allows the inhalation mode of administration of proteins and the continuous monitoring of lung compliance and other parameters is needed. The objectives of this study consequently were to (1) adapt the isolated perfused rat lung (IPL) to allow the administration of exogenous protein via the inhalation route into the alveoli, and (2) to use the adapted model to investigate the effect which inhaled cationic poly-peptides could have on lung function. It was hypothesised that such inhaled cationic peptides would interact with and inactivate the pulmonary surfactant leading to a decrease in lung compliance The lungs from adult Wistar rats were isolated and mounted in the IPL system. Three administration methods viz. aerosol administration, propellent driven administration and intra-tracheal instillation during positive pressure ventilation were considered.
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    The genetic organisation of a 2,966 basepair DNA fragment of a Single Capsid Nucleopolyhedrovirus isolated from Trichoplusia ni
    (Springer Verlag, 2002) Fielding, Burtram C.; Khan, Sehaam; Wang, Weizhou; Kruger, Courtney; Abrahams, Rayaana; Davison, Sean
    In order to investiagte the genomic organization of the Trichoplusia ni Single Capsid Nucleoplyhedrovirus (TnSNPV) , a 2,966 base pairs (bp) genomic fragment was sequenced. The fragment was found to contain five open reading frames (ORF's) homologous to baculovirus genes, including p26, fibrillin (p10), AcMNPV ORF-29, late expression facor 6 (lef 6) and the C-terminal portion of p74, on either stand of DNA. Predicted amini acid sequences for the ORFs were compared and identity values of between 12% and 54% were observed. Clustering and arrangement of the TnSNPV genes were similar to the clustering reported for SeMNPV, confirming TnSNPV was a Group II NPV.
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    Identification, sequence analysis, and phylogeny of the immediate early gene 1 of the trichoplusia ni single nucleocapsid polyhedrosis virus
    (Springer Verlag, 2001) Wang, Weizhou; Leat, Neil; Fielding, Burtram C.; Davison, Sean
    Substantial research has been conducted on the immediate early 1 (ie-1) genes from the prototype baculovirus Autographa californica multicapsid nuclear polyhedrosis virus (AcMNPV) and the Orgyia pseudotsugata multicapsid nuclear polyhedrosis virus (OpMNPV). In both cases ie-1 gene products have been implicated in transcriptional activation and repression. In this study an ie-1 homolog was identified from Trichoplusia ni single nucleocapsid polyhedrosis virus (TniSNPV). Nucleotide sequence analysis indicated that the TniSNPV ie-1 gene consists of a 2217 nucleotide open reading frame (ORF), encoding a protein with a molecular mass of 84.464 kDa. This represents the largest baculovirus ie-1 gene characterised to date. Of the seven ie-1 homologs identified to date, the TniSNPV ie-1 shared most sequence similarity with the ie-1 gene of Spodoptera exigua MNPV (SeMNPV) (41%). At the nucleotide level, expected TATA and CAGT motifs were found to precede each ie-1 ORF. At the protein level, it was confirmed that the N-termini are poorly conserved, but share the characteristic of having a high proportion of acidic amino acids. In addition it was found that N-terminal regions significantly matched the SET domain in the Swiss-Prot prosite database. The C-terminal regions of the deduced IE-1 sequences were found to be substantially more conserved than the N-termini. Several conserved motifs were identified in the C-terminal sequences. A phylogenetic tree of nine baculovirus IE-1 proteins was constructed using maximum parsimony analysis. The phylogenetic estimation of the ie-1 genes shows that TniSNPV is a member of the previously described lepidopteran NPV group II and it is most closely related to SeMNPV.
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    The molecular characterization of trichoplusia ni single nucleocapsid nucleopolyhedrovirus: a study on early regulatory features
    (University of the Western Cape, 2003) Wang, Weizhou; Davison, S
    With the development of biological insecticides, many research efforts have been made in baculoviruses to investigate fundamental molecular aspects of these viruses, such as the function and regulation of genes, genome organization, mode of entry, DNA replication and virus factors that determine the host range and virulence. Previously, a South African Trichoplusia ni single capsid nuclear polyhedrosis virus (TnSNPV) isolate was partially characterized as a novel baculovirus. During the process of the characterization, a few late genes of the virus were identified. This thesis describes a molecular characterization of the TnSNPV early genes to gain insight into the functional roles of these genes, their unique features and further determination of the placement of TnSNPV in baculovirus phylogeny.