WONG Sek Man (Professor) Contact Information: Department of Biological Sciences National University of Singapore 14 Science Drive 4 Singapore 117543 Tel: 65162976 Fax:67792486 email: dbswsm@nus.edu.sg

Research Areas:
Plant pathology, virology, molecular biology, structural biology, biotechnology, nanotechnology.

Research Interests:
Molecular biology of plant viruses, discovery of new viruses, virus replication and translation mechanisms, rapid and sensitive detection of viruses, synergism in virus-virus and virus-host Interactions, virus novel gene functions, protein expression using plant viral vectors, virus resistant transgenic plants, structural biology and bioinformatics of viruses, use of plant viruses as nano-materials for drug delivery, RNA interference.

Current Projects:
Development of plant viral vectors
Our laboratory has synthesized several full-length biologically active cDNA clones of plant viruses, namely the ageratum yellow vein virus (AYVV), cymbidium mosaic virus (CymMV), odontoglossum ringspot virus (ORSV), and hibiscus chlorotic ringspot virus (HCRSV). Recently we have expressed a neuropepetide nocistatin using ORSV and an allergen derPII using potato virus X (PVX). We are now working on obtaining the biologically active clones of Hibiscus latent Singapore virus (HLSV) and zucchini yellow mosaic virus (ZYMV).

Investigation of novel viral genes of HCRSV and HLSV
We have discovered two novel viral open reading frames (ORFs) in HCRSV, namely the p23 and the p25 ORFs. The p23 is required for virus replication and the p25 is believed to be required for virus movement. We are now verifying the existence of the different isoforms of p25 and to investigate their functions.

Production of virus-resistant transgenic orchids and watermelons
We are now working towards producing virus-resistant transgenic orchids and watermelons. From our orchid virus sequence survey, we found that coat protein sequences of two prevalent viruses, namely the CymMV and ORSV, share high sequence homology. This information is crucial to the successful production of virus resistant plants. In collaboration with colleagues in China, progress has been made to produce virus resistant watermelons.

Production of monoclonal antibodies against SARS virus N protein
We have expressed the N protein of the SARS virus and are in the process of generating monoclonal antibodies against it. We hope to use the monoclonal antibodies generated as diagnostic reagents for SARS virus in human.

Research Accomplishments:

• Determination of full-length sequences and generation of biologically-active cDNA clones of two most prevalent orchid viruses - CymMV and ORSV.

• Discovery of two novel open reading frames from HCRSV and a polyA tract in HLSV.

• Molecular characterization of AYVV, CMV and ZYMV.

• Successful application of non-radioactive cRNA probes, polymerase chain reaction, capillary electrophoresis, molecular beacons and quartz crystal microbalance for plant virus detection.

Selected Publications:

• Cheng A, Speir JA, Yuan YA, Johnson JE and Wong SM. (2009). Preliminary X-ray data analysis of crystalline hibiscus chlorotic ringspot virus. Acta Cryst. F65: 589-593.

• Ajjikuttira PA and Wong SM. (2009). Molecular biology of two orchid infecting viruses: Cymbidium mosaic potexvirus and Odontoglossum ringspot tobamovirus (Chapter 8) in Orchid Biology: Reviews and Perspectives X. K. Tiiu, J. Arditti and S.M. Wong (Eds.) Springer Netherlands. 452 pp

• Cheng A, Wong SM and Yuan YA. (2009). Structural basis for dsRNA recognition by NS1 protein of influenza A virus. Cell Res. 19: 187-195.

• Meng, C., Chen, J., Ding, S.-W., Peng, J. and Wong, S.-M. (2008). Hibiscus chlorotic ringspot virus coat protein inhibits trans-acting small-interfering RNA biogenesis in Arabidopsis. J. Gen. Virol. 89: 2349 - 2358.

• Wong SM, Koh DC and Liu DX (2008). Identification of plant virus IRES. Methods Mol. Biol. 451: 125-133.

• Koh LH, Yap ML, Yik CP, Niu SN and Wong SM (2008). First report of Phytoplasma infection of grasses in Singapore. Plant Dis. 92: 317.

• Ren Y, Wong SM and Lim LY (2007). Folic acid-conjugated protein cages of a plant virus: a novel delivery platform for doxorubicin. Bioconjugate Chem. 18:836-843.

• Li W and Wong SM (2007). Host-dependent effects of the 3' untranslated region of turnip crinkle virus RNA on accumulation in Hibiscus and Arabidopsis. J Gen Virol. 88:680-687.
  

• Koh DCY, Wang XX, Wong SM and Liu DX (2006). Translation initiation at an upstream CUG codon regulates the expression of Hibiscus chlorotic ringspot virus coat protein. Virus Res. 122: 35-44.

• Zhou T, Fan ZF, Li HF and Wong SM (2006). Hibiscus chlorotic ringspot virus p27 and its isoforms affect symptom expression and potentiate virus movement in kenaf (Hibiscus cannabinus L.) MPMI 19: 948-957.

• Chun S, Fan ZF, Wong SM and Li HF (2006).Cloning of cDNAs encoding the three subunits of oxygen evolving complex in Nicotiana benthamiana and gene expression changes in tobacco leaves infected with Tobacco mosaic virus. Physiol. Mol. Plant Pathol. 68: 61-68.

• Ren YP, Wong SM and Lim LY (2006). In vitro-reassembled plant virus-like particles for loading of polyacids. J. Gen. Virol. 87: 2749-2754.

• Li WM and Wong SM. (2006). Analyses of subgenomic promoters of Hibiscus chlorotic ringspot virus and demonstration of 5' untranslated region and 3'-terminal sequences functioning as subgenomic promoters. J. Virol. 80: 3395-3405.

• Wang XX, Wong SM and Liu DX. (2006). Identification of Hepta- and Octo-Uridine stretches as sole signals for programmed +1 and -1 ribosomal frameshifting during translation of SARS-CoV ORF 3a variants. Nucleic Acids Res. 34: 1250-1260.

• Meng C, Chen J, Peng J and Wong SM. (2006). Host-induced avirulence of hibiscus chlorotic ringpsot virus mutants correlates with reduced gene-silencing suppression activity. J. Gen. Virol. 87: 451-459.

• Niu SN, Huang XS, Wong SM, Yu JL, Zhao FX, Li DW, Wang SY, Zhai GM and Shi FS. (2005). Creation of trivalent transgenic watermelon resistant to virus infection. J. Agric. Biotech. 13: 10-15.
  

• Cao SS, Wang HH, Luhur A and Wong SM. (2005). Yeast expression and characterization of SARS-CoV N protein. J. Virol. Methods 130: 83-88.
  

• Ajjikuttira P, Loh CS and Wong SM. (2005). Reciprocal function of movement proteins and complementation of long-distance movement of Cymbidium mosaic virus RNA by Odontoglossum ringspot virus coat protein. J. Gen. Virol. 86: 1543-1553.

• Mayers CN, Lee K.-C, Moore A, Wong S.-M. and Carr, JP. (2005). Salicylic acid-induced resistance to Cucumber mosaic virus in squash and Arabidopsis thaliana: contrasting mechanisms of induction and antiviral action. MPMI 18: 428-434.

• Srinivasan KG, Min BE, Ryu KH, Adkins S and Wong SM. (2005). Determination of complete nucleotide sequence of Hibiscus latent Singapore virus: Evidence for the presence of an internal poly(A) tract. Arch. Virol. 150: 153-166.

• Kaplan IB, Lee KC, Canto T, Wong SM and Palukaitis P. (2004). Host-specific encapsidation of a defective RNA 3 of Cucumber mosaic virus. J. Gen. Virol. 85: 3757-3763.

• Chatterji A, Ochoa W, Shamieh L, Salakian SP, Wong SM, Clinton G, Ghosh P, Lin T and Johnson JE. (2004). Chemical conjugation of heterologous proteins on the surface of cowpea mosaic virus. Bioconjugate Chem. 15: 807-813.

• Wang HH, Yu HH and Wong SM. (2004). Mutation of Phe50 to Ser 50 in the 126/183-kDa proteins of Odontoglossum ringspot virus abolishes virus replication but can be complemented and restored by exact reversion. J. Gen. Virol. 85: 2447-2457.

• Wang HH and Wong SM. (2004). Significance of the 3'-terminal region in minus-strand RNA synthesis of Hibiscus chlorotic ringspot virus. J. Gen. Virol. 85: 1763-1776.

• Wang, Y, Lee KC, Gaba V, Wong SM, Palukaitis P and Gal-On A. (2004). Breakage of resistance to Cucumber mosaic virus by co-infection with Zucchini yellow mosaic virus: enhancement of CMV accumulation independent of symptom expression. Arch. Virol. 149: 379-396.

• Ma M, Tan TK and Wong SM (2003). Identification and molecular phylogeny of Epulorhiza isolates from tropical orchids. Mycol. Res. 107: 1041-1049.

• Doan DNP, Lee KC, Laurinmaki P, Butcher S, Wong SM and Dokland T. (2003). Three-dimensional reconstruction of hibiscus chlorotic ringspot virus. J. Struc. Biol. 144: 253-261.

• Lee KC, Lim D, Wong SM and Dokland T. (2003) Purification, crystallization and X-ray analysis of Hibiscus chlorotic ringspot virus. Acta Cryst. D59: 1481-1483.

• Koh DC, Wong SM and Liu DX. (2003) Synergism of the 3' UTR and an internal ribosome entry site differentially enhances the translation of a plant virus coat protein. J. Biol. Chem. 278: 20565-20573.

• Liang XZ, Lucy AP, Ding SW and Wong SM. (2002). The p23 protein of Hibiscus chlorotic ringspot virus is indispensable for host-specific replication. J. Virol. 76: 12312-12319.

• Liang XZ, Lee BTK and Wong SM. (2002). Covariation in the capsid protein of Hibiscus chlorotic ringspot virus induced by serial passaging in a host restricting movement leads to avirulence in its systemic host. J. Virol. 76: 12320-12324.

• Ajjikuttira PA, Lim-Ho CL, Woon MH, Ryu KH, Chang CA, Loh CS and Wong SM. (2002). Genetic variability in the coat protein genes of two orchid viruses: Cymbidium mosaic virus and Odontoglossum ringspot virus. Arch. Virol. 147: 1943-1954.

• Lee KC, Lin SS, Yeh SD and Wong SM. (2002). Interactions between nuclear inclusion protein a (NIa) and nuclear inclusion b (NIb) of zucchini yellow mosaic virus and papaya ringspot virus. Plant Path. Bull. 11: 79-86.

• Srinivasan KG, Narendrakumar R and Wong SM. (2002). Hibiscus virus S is a new subgroup II tobamovirus: evidence from its unique coat protein and movement protein sequences. Arch. Virol. 147: 1585-1598.

• Lim AAL, Tachibana S, Watanabe Y and Wong SM. (2002). Expression and purification of a neuropeptide nocistatin using two related plant viral vectors. Gene 289: 69-79.

• Liang XZ, Ding SW and Wong SM. (2002). Development of a kenaf (Hibiscus cannabinus L.) protoplast system for replication study of Hibiscus chlorotic ringspot virus. Plant Cell Rep. 20: 982-986.

• Wong SM. (2002). Orchid Viruses - A Compendium. Pages 505-546 in: Orchid Biology: Reviews and Perspectives, VIII. T. Kull and J. Arditti (eds) Kluwer Publishers. 584 pp.

• Eun AJC, Huang L, Chew FT, Li SFY and Wong SM (2002). Detection of two orchid viruses using quartz crystal microbalance-based DNA biosensors. Phytopathology 92: 654-658.

• Maw T, Tan TK, Khor E and Wong SM (2002). Selection of Gongronella butleri strains for enhanced chitosan yield with UV mutagenesis. J. Biotechnology 95: 189-193.

• Maw T, Tan TK, E Khor and Wong SM (2002). Complete cDNA sequence of chitin deacetylase from Gongronella butleri and its phylogenetic analysis revealed clusters corresponding to taxonomic classification of fungi. J. Biosci. Bioeng. 93: 376-381.

• Koh DCY, Liu DX and Wong SM. (2002). A six-nucleotide segment within the 3’ untranslated region of Hibiscus chlorotic ringspot virus plays an essential role in translational enhancement. J. Virol. 76: 1144-1153.

• Eun AJC, Huang L, Chew FT, Li SFY and Wong SM. (2002). Detection of two orchid viruses using quartz crystal microbalance (QCM) immunosensors. J. Virol. Methods 99: 71-79.

• Koh, L.H., Cooper, J.I. & Wong, S.M. (2001) .Complete sequences and phylogenetic analyses of a Singapore isolate of broad bean wilt fabavirus. Arch. Virol. 146:135-147.

• Lee, K.C., Koh, A., Loh, C.S. & Wong, S.M. (2001) Cucurbit protoplast isolation for the study of plant virus replication. J. Virol. Methods 91:21-27.

• Saunders, K., Bedford, I.D., Briddon, R.W., Markham, P.G., Wong, S.M. & Stanley, J. (2000). A unique virus complex causes Ageratum yellow vein disease. Proc. Natl. Acad. Sci. USA 97:6890-6895.

• Huang, M, Koh, C.Y., Weng, L.J., Chang, M.L., Yap, Y.K., Zhang, L. & Wong, S.M. (2000). Complete nucleotide sequence and genome organization of Hibiscus chlorotic ringspot virus, a new member of the genus Carmoviridae: Evidence for the presence and expression of two novel open reading frames. J. Virol. 74:3149-3155.

• Li, H.W., Lucy, A.P., Guo, H.S., Li, W.X., Ji, L.H., Wong, S.M. & Ding, S.W. (1999). Strong host resistance targeted against a viral suppressor of the plant gene silencing defence mechanism. EMBO J. 18:2683-2691.