Rajashekara Laboratory

Dr. Gireesh Rajashekara
Food Animal Health Research Program – OARDC

Wooster, OH 44691
Phone: 330-263-3745
Email: rajashekara.2@osu.edu

Dr. Gireesh Rajashekara

Areas of Expertise

Animal Health
Veterinary Epidemiology
Infectious Disease Epidemiology

Research Interests

Research in my laboratory is focused on:

Understanding survival mechanisms and pathogenesis of foodborne zoonotic pathogen, Campylobacter. We are investigating the contribution of chemoreceptors, polyphosphate (poly P) and Twin Arginine Translocation (TAT) system dependent proteins in C. jejuni stress responses and virulence mechanisms and identify C. jejuni components that are regulated by these systems, understand their role in C. jejuni colonization in food producing animals as well as C. jejuni induced disease pathogenesis using animal models, and use these information to develop novel antimicrobial strategies against Campylobacter in humans as well as in food animal reservoirs. Particularly, we are interested in targeting Campylobacter proteins critical for its survival and virulence through high throughput chemical screening and targeting surface proteins as subunit vaccines.

Elucidating molecular mechanisms of how gut microflora modulates gut permeability and intestinal homeostasis and its impact on pathogenesis of enteric pathogens. Particularly, we are looking at how different lactic acid bacteria modulate host cellular pathways using high throughput microarray analysis in a gnotobiotic pig model. Further we are interested in studying the interaction of different probiotic bacteria with enteric pathogens.

Visualizing in real-time the dynamics of in vivo colonization of bacterial pathogens using novel methodologies. We have applied bioluminescent imaging combined with transposon mutagenesis to gain greater insight into plant-phytopathogens as well as plant-foodborne pathogens interactions to (i) monitor infection over time (ii) identify sites of bacterial colonization, and (iii) study the dynamics of infection including patterns of growth and clearance of bacteria in specific tissues. Further, we are combining this sensitive, real-time assay with high throughput chemical screening to identify effective sanitization strategies to control foodborne human pathogens as well as phytopathogens.

Laboratory Personnel

Selected Publications

  1. Kandasamy S, Chattha KS, Vlasova AN, Rajashekara G, Saif LJ. Lactobacilli and Bifidobacteria enhance mucosal B cell responses and differentially modulate systemic antibody responses to an oral human rotavirus vaccine in a neonatal gnotobiotic pig disease model. Gut Microbes. 2014 Sep 1:0. [Epub ahead of print] PMID: 25483333
  2. Kassem II, Splitter GA, Miller S, Rajashekara G. Let There Be Light! Bioluminescent Imaging to Study Bacterial Pathogenesis in Live Animals and Plants. Adv Biochem Eng Biotechnol. 2014 Nov 14. [Epub ahead of print] PMID: 25395174
  3. Kashoma IP, Kumar A, Sanad YM, Gebreyes W, Kazwala RR, Garabed R, Rajashekara G. Phenotypic and Genotypic Diversity of Thermophilic Campylobacter spp. in Commercial Turkey Flocks: A Longitudinal Study. Foodborne Pathog Dis. 2014 Nov;11(11):850-60. doi: 10.1089/fpd.2014.1794. Epub 2014 Sep 3. PMID:25184688
  4. Kumar A, Vlasova AN, Liu Z, Chattha KS, Kandasamy S, Esseili M, Zhang X, Rajashekara G, Saif LJ. (2014). In vivo gut transcriptome responses to Lactobacillus rhamnosus GG and Lactobacillus acidophilus in neonatal gnotobiotic piglets. Gut Microbes. Mar-Apr;5(2):152-64. PMID: 24637605
  5. Malde A, Gangaiah D, Chandrashekhar K, Pina-Mimbela R, Torrelles JB, Rajashekara G. (2014). Functional characterization of exopolyphosphatase/guanosine pentaphosphate phosphohydrolase (PPX/GPPA) of Campylobacter jejuni. Virulence. Feb 25;5(4). PMID: 24569519
  6. Kassem II, Khatri M, Sanad YM, Wolboldt M, Saif YM, Olson JW, Rajashekara G. (2014). The impairment of methylmenaquinol:fumarate reductase affects hydrogen peroxide susceptibility and accumulation in Campylobacter jejuni. Microbiologyopen. Feb 7. doi: 10.1002/mbo3.158. PMID: 24515965