Shigellosis or bacillary dysentery caused by Shigella spp is a significant public health concern. S. flexneri is the predominant species in endemic areas and the principal cause of morbidity and mortality in young children in developing countries. S. flexneri serotypes are determined by bacterial cell-surface polysaccharides called O-antigens. My group investigates the molecular mechanism of the O-antigen modification in S. flexneri by studying the structure and function of the transferase proteins responsible for these modifications. We discover novel virulence factors by carrying out functional genomics of Shigella and its bacteriophages; the approach allows us to identify factors not only involved in serotype conversion but also in Shigella pathogenesis. We apply this knowledge for designing an effective and broad-spectrum vaccine to provide the broadest possible coverage against the majority of Shigella strains found worldwide.
- Parajuli, P, Minh, B and Verma, NK (2020) Newly emerged serotype 1c of Shigella flexneri: multiple origins and changing drug-resistance landscape. Genes, 11, 1042; doi:10.3390/genes11091042.
- Sen, T and Verma, NK (2020) Functional Annotation and Curation of Hypothetical Proteins Present in A Newly Emerged Serotype 1c of Shigella flexneri: Emphasis on Selecting Targets for Virulence and Vaccine Design Studies. Genes 23;11(3):340. doi: 10.3390/genes11030340.
- Somasiri, P, Behm, CA, Adamski, M, Wen J and Verma, NK (2019) Transcriptional response of Caenorhabditis elegans when exposed to Shigella flexneri. Genomics. https://doi.org/10.1016/j.ygeno.2019.05.016
- Parajuli, P, Deimel LP and Verma NK (2019) Genome Analysis of Shigella flexneri Serotype 3b Strain SFL1520 Reveals Significant Horizontal Gene Acquisitions Including a Multidrug Resistance Cassette. Genome Biol Evol. 11(3):776-785.
- Parajuli, P, Rajput, MI and Verma, NK (2019) Plasmids of Shigella flexneri serotype 1c strain Y394 provide advantages to bacteria in the host. BMC Microbiology 29;19(1):86.
- Parajuli, P, Adamski M and Verma NK (2017) Bacteriophages are the major drivers of Shigella flexneri serotype 1c genome plasticity: a complete genome analysis. BMC Genomics 18:722.
- Tang SS, Carlin NIA, Talukder KA, Cam PD and Verma NK (2016) Shigella flexneri serotype 1c derived from serotype 1a by acquisition of gtrIC gene cluster via a bacteriophage. BMC Microbiology 16:127.
- Jakhetia R and Verma NK (2015) Identification and Molecular Characterisation of a Novel Mu-Like Bacteriophage, SfMu, of Shigella flexneri. PLoS One 10(4):e0124053.
- Jakhetia R, Marri A, Ståhle J, Widmalm G, Verma NK (2014) Serotype-conversion in Shigella flexneri: identification of a novel bacteriophage, Sf101, from a serotype 7a strain. BMC Genomics 15(1):742.
- George DT, Behm CA, Hall DH, Mathesius U, Rug M, Nguyen KC, Verma NK (2014) Shigella flexneri Infection in Caenorhabditis elegans: Cytopathological Examination and Identification of Host Responses. PLoS One 9(9):e106085
- George, D., Mathesius, U., Behm, C. and Verma, N.K. (2014) The periplasmic enzyme, AnsB, of Shigella flexneri modulates bacterial adherence to host epithelial cells. PLoS One 9(4):e94954
- Jakhetia, R., Talukder, K.A. and Verma, N.K. (2013) Isolation, characterization and comparative genomics of bacteriophage SfIV: a novel serotype converting phage from Shigella flexneri. BMC Genomics 14:677.
- Rusden, A.D., Stephenson, D.P. and Verma, N.K. (2013) Topological Investigation of Glucosyltransferase V in Shigella flexneri using the Substituted Cysteine Accessibility Method. Biochemistry 16;52(15):2655-2661.
- Thanweer F and Verma, N.K. (2012) Identification of critical residues of the serotype modifying O-acetyltransferase of Shigella flexneri. BMC Biochem.15: 13(1):13-21.
- Linterman, M., Beaton, L., Yu, D., Ramiscal, R., Srivastava, M., Hogan, J., Verma, N.K., Smyth M., Rigby, R. and Vinuesa, C.G. (2010) IL-21 acts directly on B cells to regulate Bcl-6 expression and germinal center responses. Journal of Experimental Medicine 207: 353 - 363.
- Stagg, R., Tang, Swee-Seong, Carlin, N.,Talukder, K., Cam, P. and Verma, N. K. (2009) A novel glucosyltransferase involved in O-antigen modification of Shigella flexneri serotype 1c. Journal of Bacteriology 191: 6612 - 6617.
- Korres, H. and Verma, N. K. (2006) Identification of essential loops and residues of Glucosyltransferase V (GtrV) of Shigella flexneri. Molecular Membrane Biology 23: 407-419.
- Lehane, A.M., Korres, H. and Verma N.K. (2005) Bacteriophage-encoded glucosyltransferase GtrII of Shigella flexneri : membrane topology and identification of critical residues. Biochemical J., 389: 137-143.
- Korres, H. and Verma, N. K. (2004) Topological analysis of glucosyltransferase GtrV of Shigella flexneri by a dual reporter system and identification of a unique reentrant loop. Journal of Biological Chemistry 279: 22469-22476.
- Jennison, A.V. and Verma, N.K. (2004) Shigella flexneri infection: pathogenesis and vaccine development. FEMS Microbiology Reviews 28: 43-58.
- Allison, G.E., Angeles, D., Tran-Dinh, N. and Verma, N.K. (2002) The complete genome sequence of SfV, a serotype-converting temperate bacteriophage of Shigella flexneri. Journal of Bacteriology 184: 1974-1987.
- Allison, G.E. and Verma, N.K. (2000) Serotype-converting bacteriophages and O-antigen modification in Shigella flexneri. Trends in Microbiology 8: 17-23.
BSB PhD Exit Seminar: Study of bacteriophage encoded glucosyltransferase genes (gtr) in Shigella flexneri serotype 1c
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I enjoy sharing my enthusiasm and passion for microbiology with students.