Jane Heffernan Assistant Professor Mathematics and Statistics York University

Dr. Jane Heffernan

Department of Mathematics and Statistics

York University

Title: "Models of HIV Infection: Natural Variability and Drug Therapy "

Understanding how the human immunodeficiency virus (HIV) infects and eventually weakens the immune
system is one of the most important medical problems of the 21st century. Mathematical models of
HIV infection describing virus and immune system dynamics have contributed significantly to the
understanding of HIV pathogenesis within a single individual, "in-host". However, the majority of
these models are deterministic, ignoring the stochastic nature of HIV dynamics. Thus, the expected
variability of clinically relevant measures cannot be estimated. We have developed a Monte Carlo
model of in-host HIV dynamics. The simulation proceeds at the level of individual cells and HIV
virions, thus capturing the inherent stochasticity in viral replication and T-cell infection. Simple
modifications permit the incorporation of pharmacokinetic models of drug therapy and prediction of
the clearance probability of an initial inoculum of virus. The simulation is used to determine the
sensitivity in important model parameters, such as the basic reproductive ratio (R0), the initial
growth rate and the infected equilibrium, to the underlying T-cell and HIV virion lifetime distributions.