Different paths – the same virulence: Experimental study on avian single and co-infections with Plasmodium relictum and P. elongatum

In the present experimental study we analysed the development of two avian malarial parasites Plasmodium elongatum (genetic lineage pERIRUB01) and Plasmodium relictum (genetic lineage pSGS1) and their impact on host fitness during single and co-infections. We reveal that P. elongatum intensity of parasitemia is enhanced by the presence of P. relictum during co-infection, while the parasitemia of P. relictum stays the same. This illustrates how development of a parasite (P. elongatum) which infects both mature and young (polychromatic) red blood cells (RBCs) is facilitated during co-infection with a parasite which specializes on adult RBCs only (P. relictum). The virulence of co-infections was similar to that of the more virulent parasite (P. elongatum). However, the profile of infection and the mechanisms that caused mortality were different.

在本项实验研究中，我们对两种禽类疟原虫——即伸长疟原虫（遗传谱系pERIRUB01）和遗迹疟原虫（遗传谱系pSGS1）——的发育过程及其在单一感染和混合感染中对宿主适应能力的影响进行了分析。研究发现，在混合感染期间，遗迹疟原虫的存在增强了伸长疟原虫的寄血症强度，而遗迹疟原虫的寄血症强度保持不变。此现象揭示了当一种寄生于成熟及幼年（多色）红细胞（RBCs）的寄生虫（伸长疟原虫）与仅寄生于成年红细胞的寄生虫（遗迹疟原虫）混合感染时，前者发育得以加速的机制。混合感染的致病性类似于致病性更强的寄生虫（伸长疟原虫），然而感染模式和导致死亡的机制却存在差异。