Ka Yin Leung

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Bacterial pathogens use different protein secretion systems to deliver virulence factors. Recently, a novel secretion system was discovered in several Gram-negative bacterial pathogens, and was designated as the type VI secretion system (T6SS). In Edwardsiella tarda, a partial E. tardavirulent protein (EVP) gene cluster was implicated in protein secretion.(More)
The nuclear factor kappaB (NF-kappaB) transcription factor is responsive to specific cytokines and stress and is often activated in association with cell damage and growth arrest in eukaryotes. NF-kappaB is a heterodimeric protein, typically composed of 50- and 65-kilodalton subunits of the Rel family, of which RelA(p65) stimulates transcription of diverse(More)
The latent period of AIDS is influenced by factors which activate human immunodeficiency virus (HIV) replication in different cell types. Although monocytic cells may provide a reservoir for virus production in vivo, their regulation of HIV transcription has not been defined. We now report that HIV gene expression in the monocyte lineage is regulated by(More)
Edwardsiella tarda is an important cause of haemorrhagic septicaemia in fish and also of gastro- and extraintestinal infections in humans. Using a combination of comparative proteomics and TnphoA mutagenesis, we have identified five proteins that may contribute to E. tarda PPD130/91 pathogenesis. Lowered protein secretion, impaired autoaggregation and the(More)
Salmonella species are facultative intracellular pathogens that invade epithelial cells and reside within lysosomal membrane glycoprotein (lgp)-containing vacuoles. Coincident with the onset of bacterial replication inside these vacuoles, Salmonella induce the formation of stable lgp-containing filamentous structures that connect with the(More)
The recently identified type VI secretion system (T6SS) is implicated in the virulence of many gram-negative bacteria. Edwardsiella tarda is an important cause of hemorrhagic septicemia in fish and also gastro- and extra-intestinal infections in humans. The E. tardavirulent protein (EVP) gene cluster encodes a conserved T6SS which contains 16 open reading(More)
Edwardsiella tarda is an important cause of hemorrhagic septicemia in fish and also of gastro- and extraintestinal infections in humans. Here, we report the identification of 14 virulence genes of pathogenic E. tarda that are essential for disseminated infection, via a genome-wide analysis. We screened 490 alkaline phosphatase fusion mutants from a library(More)
Like other viruses that infect primate cells, the human T lymphotropic virus-I (HTLV-I) stimulates production of some host cell proteins. In particular, HTLV-I infected T cells synthesize interleukin-2 receptor alpha (IL-2R alpha) chain, which is probably induced through the mediation of the tat-I gene product of the virus. Activated T cells contain a(More)
Salmonella species invade and replicate within epithelial cells in membrane-bound vacuoles. In this report we show that upon infection of HeLa epithelial cells, Salmonella typhimurium residues in vacuoles that contain lysosomal membrane glycoproteins (lgps). Four to six hours after invasion, intracellular bacteria induce the formation of stable filamentous(More)
Vascular cell adhesion molecule 1 (VCAM-1) is expressed in both endothelial and epithelial cell types, where it contributes to lymphocyte migration to sites of inflammation. Its expression is regulated by cytokines, in part through two kappa B-like regulatory elements. Because NF-kappa B can be composed of multiple alternative subunits with differential(More)