RESEARCH IN THE MELVILLE LAB

Type IV pili in C. perfringens-  We discovered  that C. perfringens, a gram-positive bacterium has type IV pili (TFP) and uses these to move across agar plates with a kind of gliding motility.  We are researching the underlying mechanisms for explaining how TFP function in virulence and the molecular mechanisms used to assemble the pili themselves.

Videos showing motility:

Survival of C. perfringens in host tissues-  C. perfringens causes the lethal infection called gas gangrene.  This disease is 100% fatal if not treated.  We are using molecular techniques to identify virulence factors used by the bacterium to allow it to completely overwhelm the immune system and prevent itself from being killed.  We have discovered that macrophages play an unexpected role in limiting gas gangrene progression and also that phagocytosed C. perfringens can escape the phagosome and survive inside macrophages.  We are examining the role of toxins made by the bacteria to see how they contribute to this process.

Factors leading to heat resistance in spores made by C. perfringens-  C. perfringens is estimated to be the third common cause of bacterial food poisoning in the U. S.  It causes food poisoning by releasing a toxin (called CPE) in the intestines of patients who ingest food contaminated by the bacterium.  The bacteria only synthesize and release CPE when they are sporulating.  We are examining factors that allow the spores made by C. perfringens to resist being killed by normal cooking procedures.  We are also examining the connection between sporulation and CPE synthesis at the molecular level to try and understand how these complex process are co-regulated.

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