Determining the role of the SpiCprotein in Salmonella

typhimurium infection of the model organism, C. elegans

Ajay SinghPine Crest School, 11th grade

Research conducted at Florida Atlantic University

Salmonella Outbreaks!

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.

To determine the importance of the role of

the SpiC protein in Salmonella typhimurium

infection

Purpose

The deletion of SpiC from Salmonella typhimurium will decrease the virulence and lethality of the Salmonella

infection.

Hypothesis

Methods and Design

3 groups of N2 (Wild type) C. elegans exposed to:

Deleted-SpiC (∆SpiC) Salmonella typhimurium

Wild-type Salmonella typhimurium

OP50 (control)

Daily Scoring

Determination of the viability of the C. elegans

Fluorodeoxyuridine Usage

Sterilization of experimental C. elegans to control population

Caenorhabditis elegans: a multicellular nematode, commonly used in Salmonella infection studies

Strain Subjects at risk (# of subjectscensored)

Median lifespan (days)

Maximum lifespan (days)

N2 OP50 (control)

N2 ∆SpiCSalmonella

N2 WT Salmonella

62 (18)

72 (8)

63 (17)

23

20

20

32

28

29

• Noted difference between median and maximum lifespan between the N2 OP50

control group and the two Salmonella exposed groups

Trial 1

Trial 1 P-Value

N2 OP50 vs. N2 ∆SpiCSalmonella

0.0001*

N2 OP50 vs. N2 WT Salmonella

<0.0001*

N2 WT Salmonella vs. N2 ∆SpiCSalmonella

0.5381

* Denotes significant difference

Survival Curve for Trial 1

Strain Subjects at risk (# of subjectscensored)

Median lifespan (days)

Maximum lifespan (days)

N2 OP50 (control)

N2 ∆SpiCSalmonella

N2 WT Salmonella

53 (27)

51 (29)

65 (15)

27

25

26

40

36

36

• Noted difference between median and maximum lifespan between the N2 OP50

control group and the two Salmonella groups

Trial 2

Trial 2 P-Value

N2 OP50 vs. N2 ∆SpiCSalmonella

0.0016*

N2 OP50 vs. N2 WT Salmonella

0.0008*

N2 WT Salmonella vs. N2 ∆SpiCSalmonella

0.9810

* Denotes significant difference

Survival Curve for Trial 2

Conclusions

The deletion of the SpiCprotein did NOT affect the virulence of Salmonella typhimurium infection

The SpiC protein does not play an important role in Salmonella typhimuriuminfection in C. elegans.

Significance

Focusing on pathogen-host protein interaction to create novel curative and preventative measures for infection

Increases the effectiveness of C. elegans as a model organism

Testing ∆SifA and ∆SopD2 Salmonella strainBoth SifA and SopD2 are

proteins directly related to Salmonella induced filament formationFurther test for Salmonella

induced filaments’ role in infection of C. elegans

Future Research