Kosinski R J
Parasitology. 1980 Apr;80(2):343-57. doi: 10.1017/s0031182000000809.
African trypanosomes can undergo antigenic variation and evade the host immune response. Whether the antigenic variants arise in an ordered sequence or randomly has been in dispute but has not been statistically tested. The coefficient of concordance (W), a statistic designed to detect similarities between sequences of objects, was applied to the literature data. The tendency towards a reproducible order of variants was strong, although in several of the studies the number of experimental animals was so low that no conclusions could be drawn. A computer model was used to determine whether this degree of order could arise with random generation of variants followed by selection. The model simulated a trypanosome clone with 90 possible variants, widely differing variant-specific growth rates, random variant origin and variant eradication by an anamnestic host immune response. Parameters varied were maximum parasitaemia, growth rate differential between 'fast' and 'slow' variants, and parasitologist ability to detect minor variants. Random generation and selection by growth rate alone could not produce the degree of variant orderliness reported in the literature. However, experiments with larger numbers of host animals and direct investigation of variant growth rates and competitive interactions are necessary before the random generation-selection hypothesis can be proven or disproven.
非洲锥虫能够发生抗原变异并逃避宿主的免疫反应。抗原变异体是以有序序列出现还是随机出现一直存在争议，但尚未进行统计学检验。一致性系数（W）是一种用于检测对象序列之间相似性的统计量，被应用于文献数据。变异体出现可重复顺序的趋势很强，尽管在一些研究中实验动物的数量过少，无法得出结论。使用计算机模型来确定这种程度的顺序是否可以在变异体随机产生后通过选择出现。该模型模拟了一个具有90种可能变异体的锥虫克隆，变异体特异性生长速率差异很大，变异体随机产生，并通过记忆性宿主免疫反应清除变异体。变化的参数包括最大寄生虫血症、“快速”和“慢速”变异体之间的生长速率差异以及寄生虫学家检测微小变异体的能力。仅通过生长速率进行随机产生和选择无法产生文献中报道的变异体有序程度。然而，在随机产生-选择假说被证实或证伪之前，需要进行更多宿主动物的实验，并直接研究变异体的生长速率和竞争相互作用。
