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Curriculum vitae

Bacterial Pathogenesis Laboratory 

Microbiology Cover page Nov 1998

Microbiology Cover page Jan 2000

LEUNG Ka Yin (Associate Professor)   Contact Information:  Dept  of Biological Sciences National University of Singapore Science Drive 4 Singapore 117543 Tel: 65167835 Fax:6 7792486 email: dbslky@nus.edu.sg

Research Areas

Bacterial Pathogenesis, Use of Genomics and Proteomics to Identity Virulence Factors, Type III and Other Novel Secretion Systems, Development of Diagnostic Kits, Vaccines and Drug Discovery

Research Interests

Our laboratory has been working on the pathogenesis of bacteria and the characterization of virulence determinants. Common bacterial pathogens are Aeromonas hydrophila, Edwardsiella tarda and Enterohemorrhagic Escherichia coli (EHEC) that are the causative agents of systemic or enteric infections in a wide variety of animals and humans. Our objective is to identify virulence mechanisms and to characterize their corresponding virulence genes/proteins through genomics and proteomics approaches. We are interested to locate virulent gene clusters and pathogenicity islands in these pathogens. Many important virulence genes and genomic islands have been identified by genome subtraction, transposon tagging, and comparative proteomics analysis. Knockouts have been constructed to characterize their biological functions. Recently, type III and other novel secretion systems have been discovered by us in A. hydrophila and E. tarda and were shown to play important roles in pathogenesis. We are now examining their regulation and characterizing the roles of effector proteins in host-bacteria interactions. At the same time, a database is being set up based on the DNA microarray and proteomics data. This database will be used for gene-mining and drug discovery. The knowledge generated will be used to answer fundamental questions such as what make bacteria pathogenic as well as for the designing of sensitive diagnostic kits, vaccines development, and screening of new drugs against animal and human diseases.

Selected Publications

1. Yu, H.B., R. Kuar, S. Lim, X.H. Wang & K.Y. Leung. (2007) Characterization of extracellular proteins produced by Aeromonas hydrophila AH-1. Proteomics. (in press)

2. Li, M., I. Rosenshine, H.B. Yu, C. Nadler, E. Mills, C.L. Hew, & K.Y.Leung. (2006). Identification and characterization of NleI, a new non-LEE-encoded effector of enteropathogenic Escherichia coli (EPEC). Microbes and Infection. 8:2890-2898.

3. Yu, H.B., Y.L. Zhang, Y.L. Lau, F. Yao, S. Vilches, S. Merino, J.M. Tomas, S.P. Howard, & K.Y. Leung. (2005). Identification and characterization of putative virulence genes and gene clusters in Aeromonas hydrophila PPD134/91. Applied and Environmental Microbiology 71:4469-4477.

4. Tan, Y.P., J. Zheng, S.L. Tung, I. Rosenshine, & K.Y. Leung. (2005) Role of type III secretion in Edwardsiella tarda virulence. Microbiology. 151:2301-2313.

5. Zheng, J., S.L. Tung, K.Y. Leung. (2005) Regulation of a type III and a putative secretion system in Edwardsiella tarda by EsrC is under the control of a two-component system, EsrA-EsrB. Infection and Immunity. 73:4127-4137.

6. Srinivasa Rao, P.S., Y. Yamada, Y.P. Tan & K.Y. Leung. (2004) Use of proteomics to identify novel virulence determinants that are required for Edwardsiella tarda pathogenesis. Molecular Microbiology 53: 573-586.

7. Li, M., I. Rosenshine, S.L. Tung, X.H. Wang, C.L. Hew & K.Y. Leung. (2004) Comparative proteomics analysis of extracellular proteins of enterohemorrhagic and enteropathogenic Escherichia coli and their ihf and ler mutants. Applied and Environmental Microbiology 70:5274-5282.

8. Yu, H.B., P.S. Srinivasa Rao, H.C. Lee, S. Vilches, S. Merino, J.M. Tomas & K.Y. Leung. (2004) Type III secretion system is required for Aeromonas hydrophila AH-1 pathogenesis. Infection and Immunity 72, 1248-1256.

9. Srinivasa Rao, P.S., T.M. Lim & K.Y. Leung. (2003) Functional genomics approach to the identification of virulence genes involved in Edwardsiella tarda pathogenesis. Infection and Immunity 71, 1343-1351.

10. Tan, Y.P., Q. Lin, X.H. Wang, S. Joshi, C.L. Hew & K.Y. Leung. (2002) Comparative proteomic analysis of extracellular proteins of Edwardsiella tarda. Infection and Immunity 70, 6475-6480.

11. Zhang, Y.L., E. Arakawa & K.Y. Leung. (2002) Novel Aeromonas hydrophila PPD134/91 genes involved in O-antigen and capsule biosynthesis. Infection and Immunity 70, 2326-2335.

12. Zhang, Y.L., C.T. Ong & K.Y. Leung. (2000) Molecular analysis of genetic differences between virulent and avirulent strains of Aeromonas hydrophila isolated from diseased fish. Microbiology 146, 999-1009.

13. Ling, S.H.M., X.H. Wang, L. Xie, T.M. Lim & K.Y. Leung. (2000) Use of green fluorescent protein (GFP) to study the invasion pathways of Edwardsiella tarda in in vivo and in vitro fish models. Microbiology 146, 7-19 (with front cover photograph).

14. Wang, X.H., H.L. Oon, G.W.P. Ho, W.S.F. Wong, T.M. Lim & K.Y.Leung. (1998) Internalization and cytotoxicity are important virulence mechanisms in vibrio-fish epithelial cell interactions. Microbiology 144, 2987-3002 (with front cover photograph).

15. Garcia-del Portillo, F., M.B. Zwick, K.Y. Leung & B.B. Finlay. (1993) Salmonella induces the formation of filamentous structures containing lysosomal membrane - glycoproteins in epithelial cells. Proceedings of the National Academy of Sciences, USA 90, 10544-10548.

16. Leung, K.Y. & B. B. Finlay. (1991) Intracellular replication is essential for the virulence of Salmonella typhimurium. Proceedings of the National Academy of Sciences, USA 88, 11470-11474.