A well identifiable trait of each pathogen which inhibits its growth. The method of identification is through colour. Suppression cannot completely cure a pathogen, however, its destructive potential may be severely limited by suppression.
Suppressants may react to events the same way symptoms can - as suppressants are instantiated per pathogen, they may have their own internal state without breaking anything.
Suppressants also play a large role in the synthesis of cure for all default microbodies - each suppressant indicates a list of reagents which may be used for cure synthesis. Curing therefore requires at least some analysis of the pathogen.