Diversity patterns in parasite populations capable forpersistence and reinfection

Abstract

Many parasites like the cytomegalovirus, HIV and Escherichia coli are capable to persist in and reinfect its host. The evolutionary advantage (if so) of these complicated mechanisms have not been quantitatively analyzed so far. Here we take a first step by investigating a host-parasite model for which these mechanisms are driving the evolution of the parasite population. We consider two variants of the model. In one variant parasite reproduction is directed by balancing selection, in the other variant parasite reproduction is neutral. In the former scenario reinfection and persistence have been shown to sustain the maintenance of diversity in the parasite population in certain parameter regimes (Pokalyuk and Wakolbinger, 2018). Here we analyse the diversity patterns in the latter, neutral scenario. We evaluate the biological relevance of both model variants with respect to the human cytomegalovirus (HCMV), an ancient herpesvirus that is carried by a substantial fraction of mankind and manages to maintain a high diversity in its coding regions.