Preferential Invasion by <em>Plasmodium</em> Merozoites and the Self-Regulation of Parasite Burden

Abstract

<div><p>The preferential invasion of particular red blood cell (RBC) age classes may offer a mechanism by which certain species of <i>Plasmodia</i> regulate their population growth. Asexual reproduction of the parasite within RBCs exponentially increases the number of circulating parasites; limiting this explosion in parasite density may be key to providing sufficient time for the parasite to reproduce, and for the host to develop a specific immune response. It is critical that the role of preferential invasion in infection is properly understood to model the within-host dynamics of different <i>Plasmodia</i> species. We develop a simulation model to show that limiting the range of RBC age classes available for invasion is a credible mechanism for restricting parasite density, one which is equally as important as the maximum parasite replication rate and the duration of the erythrocytic cycle. Different species of <i>Plasmodia</i> that regularly infect humans exhibit different preferences for RBC invasion, with all species except <i>P. falciparum</i> appearing to exhibit a combination of characteristics which are able to self-regulate parasite density.</p> </div>