Viruses and Immune Responses: A Dynamical View

Abstract

One of the most complicated organs of higher organisms is the immune system. The function of the immune system is to fight off pathogenic organisms that enter and grow within the host (for example viruses, bacteria, unicellular eukaryotic parasites such as malaria, and multicellular parasites such as worms). Detailed molecular research has elucidated how immune cells function, that is, how they recognize an invading pathogen and mount orchestrated responses that fight the infection and protect the host. In addition to understanding how the individual components of the immune system work, it is also important to take a “systems approach” and to investigate how the complex interactions between the many components of the immune system work together and determine the outcome of an infection. In a nutshell, this is the subject of this book. In particular, the interactions between pathogens and the immune system can be viewed as an ecological system within the body of an organism. Specifically, the area of population ecology or population dynamics has relevance. Several species of immune cells interact with populations of pathogens in various ways. Two especially important population dynamic interactions that are found in the immune system are predator-prey interactions and competition. (i) When predators capture and kill their prey, they reproduce such that their population size grows. This in turn has a negative impact on the prey population. In the absence of prey, predators die. The outcomes of such interactions can involve cycles in the population sizes of predators and prey that can dampen over time.