Metagenomics is currently the primary means for identifying new viruses. One of the most impactful metagenomic discoveries is that of crAssphage, the most abundant human-associated virus that is found in about 50% of human gut viromes where it can comprise up to 90% of the virus sequences. Although initial genome analysis of crAssphage failed to detect related phages, or functionally annotate most of the genes, subsequent reanalysis with powerful computational methods and larger databases led to the identification of an expansive group of crAss-like phages. The functions of most crAssphage proteins were predicted, including unusual ones such as giant RNA polymerase polyproteins. The host range of the crAss-like phages consists of various members of the bacterial phylum Bacteroidetes as demonstrated by CRISPR spacer analysis and by analysis of genes acquired by phages from the hosts. New metagenomic studies vastly expanded the crAss-like phage group and demonstrated its global spread and ancient association with primates. The first members of the crAss-like group was recently isolated and shown to infect the bacterium Bacteroides intestinales. Characterization of this phage validated the predicted podovirus-like virion structure and the identity of the major capsid protein and other predicted virion proteins, including three RNA polymerase subunits.

元基因组学目前是识别新病毒的主要手段。最具影响力的宏基因组学发现之一是crAssphage，它是最丰富的人类相关病毒，在约50％的人肠道病毒中发现，其中最多可包含90％的病毒序列。尽管最初对crAssphage的基因组分析未能检测到相关的噬菌体，或在功能上注释了大多数基因，但随后通过强大的计算方法和更大的数据库进行的重新分析导致鉴定出了一组广泛的crAss样噬菌体。可以预测大多数crAssphage蛋白的功能，包括不寻常的蛋白，例如巨型RNA聚合酶多蛋白。crAss样噬菌体的宿主范围由细菌门细菌的各种成员组成，如CRISPR间隔分析和噬菌体从宿主获得的基因分析所示。新的宏基因组学研究极大地扩展了类似于crAss的噬菌体组，并证明了其在全球的传播以及与灵长类动物的古老联系。最近分离出了crAss样组的第一批成员，并显示出感染了这种细菌。细菌肠。此噬菌体的表征验证了预测的足病毒样病毒体结构以及主要衣壳蛋白和其他预测的病毒体蛋白（包括三个RNA聚合酶亚基）的身份。