AEGiS-14IAC: A second order system approximation for virus dynamics.

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

A second order system approximation for virus dynamics.

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no. A10073)

Jeffrey AM, Xia X, Craig IK
University of Pretoira, Pretoria 0002, South Africa

BACKGROUND: The mathematical models that adequately describe the interaction of the immune system with the HIV virus are complicated. As a result, analysis of these models in order to determine the extent to which the various parameters influence the virus dynamics is a very tedious exercise. The models therefore need to be reduced to an order that can be easily analyzed.

METHODS: This paper shows how standard control theory can be applied to help interpret virus dynamics. The paper introduces a model reduction exercise for ease of analysis of these dynamics.

RESULTS: The fourth order model was reduced to a second order non-minimum phase model that turned out to be simpler and just as good at providing the virus dynamics. This simpler lower order model however, makes it easier to compute the rise, peak and settling times for the virus as well as the steady state, percentage overshoot and the peak decay ratio. The model can therefore, be used to identify parameters that determine, among others, the peak viral load, the steady state viral load and the associated time scales.

CONCLUSIONS: It can be shown that the second order approximation can model the virus dynamics adequately and simplified the task of determining the extent to which the model parameters influence the virus dynamics. The characteristics of the simplified second order system lend themselves to determining key information about disease progression.

Keywords: AEGIS, Viral Load, HIV Infections, HIV, Anti-HIV Agents, Disease Progression, Models, Theoretical, HIV Protease Inhibitors

020707
A10073