Determining the role of the SpiC protein in Salmonella typhimurium infection of the model organism, C. elegans Ajay Singh Pine Crest School, 11th grade Research conducted at Florida Atlantic University
Background Salmonella typhimurium A pathogenic, gram-negative bacteria that causes intestinal infection in humans People come into contact with bacteria through consumption of contaminated food or when dealing with infected animals SpiC protein = candidate protein of importance in Salmonella typhimurium infection Regulator of translocon proteins which create channels for other effector proteins to propagate virulence Associated with creation of Salmonella induced filaments which are important in the survivability of Salmonella.
Purpose To determine theimportance of the role of the SpiC protein in Salmonella typhimurium infection
Hypothesis The deletion of SpiC fromSalmonella typhimurium willdecrease the virulence and lethality of the Salmonella infection.
Methods and Design 3 groups of N2 (Wild type) C. elegans exposed to: Deleted-SpiC (∆SpiC) Salmonella typhimurium Wild-type Salmonella typhimurium OP50 (control) Caenorhabditis elegans: a multicellular nematode, Daily Scoring commonly used in Salmonella infection studies Determination of the viability of the C. elegans Fluorodeoxyuridine Usage Sterilization of experimental C. elegans to control population
Trial 1Strain Subjects at risk (# Median lifespan Maximum lifespan of subjects (days) (days) censored)N2 OP50 (control) 62 (18) 23 32N2 ∆SpiC 72 (8) 20 28SalmonellaN2 WT Salmonella 63 (17) 20 29 • Noted difference between median and maximum lifespan between the N2 OP50 control group and the two Salmonella exposed groups
Survival Curve for Trial 1 Trial 1 P-Value N2 OP50 0.0001* vs. N2 ∆SpiC Salmonella N2 OP50 <0.0001* vs. N2 WT Salmonella N2 WT 0.5381 Salmonella vs. N2 * Denotes significant ∆SpiC difference Salmonella
Trial 2Strain Subjects at risk (# Median lifespan Maximum lifespan of subjects (days) (days) censored)N2 OP50 (control) 53 (27) 27 40N2 ∆SpiC 51 (29) 25 36SalmonellaN2 WT 65 (15) 26 36Salmonella • Noted difference between median and maximum lifespan between the N2 OP50 control group and the two Salmonella groups
Survival Curve for Trial 2 Trial 2 P-Value N2 OP50 0.0016* vs. N2 ∆SpiC Salmonella N2 OP50 0.0008* vs. N2 WT Salmonella N2 WT 0.9810 Salmonella vs. N2 * Denotes significant ∆SpiC difference Salmonella
ConclusionsThe deletion of the SpiC protein did NOT affect the virulence of Salmonella typhimurium infectionThe SpiC protein does not play an important role in Salmonella typhimurium infection in C. elegans.
SignificanceFocusing on pathogen-host protein interaction to create novel curative and preventative measures for infectionIncreases the effectiveness of C. elegans as a model organism
Future ResearchTesting ∆SifA and ∆SopD2Salmonella strain Both SifA and SopD2 are proteins directly related to Salmonella induced filament formation Further test for Salmonella induced filaments’ role in infection of C. elegans