The infection dynamics between different species of Plasmodium that infect the same human host can both suppress and exacerbate disease. This could arise from inter-parasite interactions, such as competition, from immune regulation, or both. The occurrence of protective, cross-species (heterologous) immunity is an unlikely event, especially considering that strain-transcending immunity within a species is only partial despite lifelong exposure to that species. Here we review the literature in humans and animal models to identify the contexts where heterologous immunity can arise, and which antigens may be involved. From the perspective of vaccine design, understanding the mechanisms by which exposure to an antigen from one species can elicit a protective response to another species offers an alternative strategy to conventional approaches that focus on immunodominant antigens within a single species. The underlying hypothesis is that certain epitopes are conserved across evolution, in sequence or in structure, and shared in antigens from different species. Vaccines that focus on conserved epitopes may overcome the challenges posed by polymorphic immunodominant antigens; but to uncover these epitopes requires approaches that consider the evolutionary history of protein families across species. The key question for vaccinologists will be whether vaccines that express these epitopes can elicit immune responses that are functional and contribute to protection against Plasmodium parasites.

不同物种之间的感染动态疟原虫感染同一人类宿主的病毒既可以抑制疾病，也可以加剧疾病。这可能是由于寄生虫之间的相互作用（例如竞争）、免疫调节或两者兼而有之。保护性跨物种（异源）免疫的发生是不可能的事件，特别是考虑到尽管终生接触该物种，但物种内的超越菌株的免疫只是部分的。在这里，我们回顾了人类和动物模型的文献，以确定异源免疫可能出现的背景以及可能涉及哪些抗原。从疫苗设计的角度来看，了解接触一个物种的抗原可以引发对另一个物种的保护性反应的机制，为专注于单一物种内免疫显性抗原的传统方法提供了一种替代策略。基本假设是，某些表位在进化过程中在序列或结构上是保守的，并且在不同物种的抗原中是共享的。专注于保守表位的疫苗可以克服多态性免疫显性抗原带来的挑战；但要发现这些表位，需要考虑跨物种蛋白质家族的进化历史。疫苗学家面临的关键问题是表达这些表位的疫苗是否可以引发功能性免疫反应并有助于预防疟原虫寄生虫。