We model the immune surveillance of a pathogen which passes through n immunologically distinct stages. The biological parameters of this system induce a partial order on the stages, and this, in turn, determines which stages will be subject to immune regulation. This corresponds to the system's unique asymptotically stable fixed point.
@article{arxiv.1005.0332,
title = {A model of host response to a multi-stage pathogen},
author = {Edgar Delgado-Eckert and Michael Shapiro},
journal= {arXiv preprint arXiv:1005.0332},
year = {2010}
}