INTERACTIONS BETWEEN MALARIA PARASITES INFECTING THE SAME VERTEBRATE HOST
INTERACTIONS BETWEEN MALARIA PARASITES INFECTING THE SAME VERTEBRATE HOST
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DOI：
10.1017/s0031182000080227
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发表时间：
1988-06-01
期刊：
影响因子：
2.4
通讯作者：
RICHIE, TL
中科院分区：
文献类型：
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作者：
RICHIE, TL
几种疟疾原虫通常寄生在同一宿主群体中，而且常常寄生在同一个体宿主中。本文综述了这种主机共享寄生虫之间的相互作用的证据。测量疟疾物种横断面流行率的实地研究往往记录到混合感染比偶然预期的要少，这表明一种寄生虫排斥了另一种寄生虫或将其寄生虫血症抑制到无法检测的水平。流行率在不同季节之间可能会有所不同，一个物种的流行率增加，而另一个物种则减少，尽管两者的传播率平行增加，这再次表明一个物种受到另一个物种的抑制。然而，对个体宿主的纵向研究表明，疟疾寄生虫也可能对彼此的宿主环境产生有利影响，这可能是由于它们对免疫系统的抑制作用：这表现为潜伏的疟疾物种在另一物种的寄生波之前或之后立即复发。同时将两种疟原虫接种到实验室动物身上所得的数据支持了抑制假说;许多研究表明，一种或两种疟原虫都受到抑制。这可能是通过竞争宿主细胞或营养物质或异源免疫介导的。然而，受抑制的物种反弹后，其他物种已经减弱，并可能表现出长期感染。实验证据表明，一个物种可以促进另一个复发是最小的，但这可能反映了缺乏调查这一现象。实验室研究表明，只有轻微的交叉耐药性之间的主机共享物种，这是一致的假设，它们的共同出现导致抗原分歧或物种显示出强烈的异源性耐药性不能共存于同一宿主种群。这种互补性不仅发生在宿主免疫反应中，也发生在宿主共享寄生虫的许多其他生活史特征中，如宿主细胞偏好。我的结论是，疟疾物种在彼此的进化中一直很重要，特别是在热带地区，多物种复合体很常见。
Several species of malarial protozoans commonly parasitize the same host population and often the same individual host. This paper reviews the evidence for interactions among such host-sharing parasites. Field studies measuring the cross-sectional prevalence of malarial species often record fewer mixed infections than expected by chance, suggesting that one parasite has excluded another or suppressed its parasitaemia to undetectable levels. Prevalences may vary reciprocally between seasons, with one species increasing in prevalence while another decrease, despite parallel increases in the transmission rates of both, again suggesting suppression of one species by another. However, longitudinal studies of individual hosts indicate that malarial parasites may also favourably affect the host environment for each other, perhaps due to their depressive effect on the immune system: this is shown by the recrudescence of a latent malarial species immediately before or after the parasitic wave of another species. The suppression hypothesis is supported by data derived from the simultaneous inoculation of two Plasmodium species in to laboratory animals; many studies have shown that one or both species are suppressed. This may be mediated by competition for host cells or nutrients, or by heterologous immunity. However, the suppressed species rebounds after the other species has abated, and may show a prolonged infection. Experimental evidence that one species can facilitate the recrudescence of another is minimal, but this may reflect the paucity of investigations of this phenomenon. Laboratory studies show only minor cross-resistance between host-sharing species, which is consistent with the hypothesis that their co-occurrence has led to antigenic divergence or that species showing strong heterologous resistance cannot co-exist in the same host population. Such complementarity occurs not only with the host immune response but also with many other life-history characteristics of host-sharing parasites, such as host cell preference. I conclude that malarial species have been important in each others''s evolution, particularly in the tropics where multi-species complexes are common.