Comparing immune response times and pathogen replication rates across vertebrate host species: a case study in West Nile Virus (170.17)

Abstract

Abstract The vast majority of biological rates and times decrease systematically with increasing animal body size. For example, circulation times, a range of developmental times, and life span are systematically slower in larger animals. We use empirical data and ordinary differential equation (ODE) models of disease progression to show that immune response is independent of host body size, but that viral pathogen replication rates in vivo are systematically slower for larger animals. The models focus on West Nile Virus, but we suggest that this pattern holds more generally. We examine how the sizes and numbers of lymph nodes and the size of the lymphocyte repertoire enable immune responses that are similar across animals with vast differences in body size. We discuss how body size influences pathogenesis, epidemic spread of multi-host pathogens and the metabolic cost of immunity. Comparative studies of immune response and pathogen replication have implications for human health and animal disease.