Quantifying the infectivity of human immunodeficiency virus.

We have developed a mathematical model that quantifies lymphocyte infection by human immunodeficiency virus (HIV) and lymphocyte protection by blocking agents such as soluble CD4. We use this model to suggest standardized parameters for quantifying viral infectivity and to suggest techniques for calculating these parameters from well-mixed infectivity assays. We discuss the implications of the model for our understanding of the infectious process and virulence of HIV in vivo.