crAssphages are a broad group of diverse bacteriophages in the order Caudovirales that have been found to be highly abundant in the human gastrointestinal tract. Despite their high prevalence, we have an incomplete understanding of how crAssphages shape and respond to ecological and evolutionary dynamics in the gut. Here, we report genomes of crAssphages from feces of one South African woman and three infants. Across the complete genome sequences of the South African crAssphages described here, we identify particularly elevated positive selection in RNA polymerase and phage tail protein encoding genes, contrasted against purifying selection, genome-wide. We further validate these findings against a crAssphage genome from previous studies. Together, our results suggest hotspots of selection within crAssphage RNA polymerase and phage tail protein encoding genes are potentially mediated by interactions between crAssphages and their bacterial partners.

crAssphages 是一个广泛的一组不同的噬菌体，按Caudovirales的顺序已发现在人体胃肠道中含量非常丰富。尽管它们的流行率很高，但我们对 crAssphages 如何塑造和响应肠道中的生态和进化动态的理解并不完整。在这里，我们报告了一名南非妇女和三名婴儿粪便中的 crAssphages 基因组。在此处描述的南非 crAssphages 的完整基因组序列中，我们发现 RNA 聚合酶和噬菌体尾蛋白编码基因中特别升高的阳性选择，与全基因组的纯化选择形成对比。我们针对先前研究中的 crAssphage 基因组进一步验证了这些发现。一起，