Roland's research interests

My research is concerned with infectious diseases and their control. In addition to their clinical relevance, infectious diseases provide ideal biological systems to investigate fundamental questions about the ecology, evolution, and immunology of host-pathogen systems. I am interested in various aspects of the interaction between pathogens and their hosts, ranging from the molecular level, through the within-host level, up to the epidemiological level. I use mathematical models to describe biological systems quantitatively, and to obtain answers to biologically and clinically relevant questions.

Within-host dynamics and evolution of pathogens

The typically fast replication kinetics and high mutation rate of pathogens within their hosts allows us to study the population dynamics and the mechanisms of evolution on a feasibly short time-scale. Viewing the environment within the host as the ecological arena, I am applying many of the concepts of evolutionary ecology to study the dynamics of pathogens within their hosts.

The central questions that drive my research are:

• What controls pathogen replication within the host?
• What is the population dynamical and evolutionary response of the pathogen population to immune responses or drug treament?
• How do pathogens cause disease?

I have been addressing these questions, by developing specific population dynamical or statistical models for viral infections, such as HIV, cytomegalovirus, or poliovirus. More recently, I have become interested in bacterial infections.

Evolutionary ecology of host-pathogen systems

I have been studying different stages of host-pathogen evolution, ranging from the initial emergence of new pathogens to the spread and the evolution of specific host or pathogen traits, such as the virulence of the pathogen.

The questions I am/have been investigating are:

• How do new infectious diseases emerge?
• How should we describe interactions between pathogens and their hosts quantitatively?
• What factors determine the evolution of pathogen virulence?