Diversity patterns in parasite populations capable for persistence and reinfection with a view towards the human cytomegalovirus

Many parasites like the cytomegalovirus, HIV and E.coli are capable to persist in and reinfect its host. The evolutionary advantage of these (complicated) mechanisms have not been quantitatively analyzed so far. We make a first step into this direction by analyzing a hierarchical host-parasite model with two parasite types in which parasites persist in its hosts and reinfection of hosts is common. In [50] a scenario has been analyzed in which within hosts both parasite types are maintained due to balancing selection and parameter regimes have been identified in which persistence and reinfection can be effective mechanisms to maintain both parasite types in the parasite population. Here we analyze the neutral counterpart of the model with respect to the expected diversity patterns. We evaluate the biological relevance of both scenarios at the example of the human cytomegalovirus (HCMV).We argue that under neutrality the coexistence of genotypes should be relatively rare in contrast to the observation in HCMV and the observed diversity patterns in HCMV-infected host require under neutrality reinfection rates which might be unrealistically high for HCMV.