Boots M, Bowers R G
Department of Biology, Kyushu University, Higashi-ku, Fukuoka, 812-81, Japan.
J Theor Biol. 1999 Nov 7;201(1):13-23. doi: 10.1006/jtbi.1999.1009.
Parasite resistant hosts may avoid becoming infected, recover more quickly after infection or survive longer once infected. A model is constructed to examine the evolution of costly host resistance to directly transmitted microparasites and these three distinct mechanisms of avoidance, recovery and tolerance are compared. In each case polymorphism is more likely between very dissimilar strains and resistance (by which we mean the resistant strain alone) is always more likely to occur in hosts with high intrinsic productivity. However, the region where polymorphism occurs is relatively much smaller when resistance is through reduced pathogenicity. In particular, polymorphism with highly resistant strains requires correspondingly high costs. This is in contrast to avoidance or recovery resistance, where polymorphism can also occur when high resistance is associated with small costs due to the inability of highly resistant strains with low susceptibility or high recovery to support the parasite alone and hence resist invasion by the susceptible strain. Relatedly, resistance through avoidance and recovery is favoured in response to less pathogenic parasites.
具有抗寄生虫能力的宿主可能会避免被感染，感染后恢复得更快，或者一旦被感染就能存活更长时间。构建了一个模型来研究宿主对直接传播的微寄生虫产生高成本抗性的进化过程，并比较了避免感染、恢复和耐受这三种不同机制。在每种情况下，多态性在非常不同的菌株之间更有可能出现，并且抗性（我们指的是单独的抗性菌株）总是更有可能出现在具有高内在生产力的宿主中。然而，当抗性是通过降低致病性实现时，多态性出现的区域相对要小得多。特别是，与高抗性菌株的多态性需要相应的高成本。这与避免感染或恢复抗性形成对比，在避免感染或恢复抗性中，当高抗性与低成本相关时也会出现多态性，这是因为低易感性或高恢复能力的高抗性菌株无法单独支持寄生虫，从而抵抗易感菌株的入侵。相关地，针对致病性较低的寄生虫，通过避免感染和恢复产生的抗性更受青睐。
