University of York Team Reports Structure of Human Gut Crassviruses

A structural atlas of a human gut crassvirus is reported in Nature this week, providing insights into the mechanisms of assembly and infection for this viral order. CrAssphage and related viruses of the order Crassvirales — collectively known as crassviruses — are the most abundant viruses in the human gut, accounting for up to 95 percent of the viral sequences in some individuals. Crassviruses are believed to have roles in the composition and functionality of the human microbiome, but the structures and roles of most of the virally encoded proteins are unknown. In their new paper, an international team led by University of York scientists used cryo-electron microscopy to characterize ΦcrAss001, the first crassvirus to be isolated in pure culture from human fecal samples. The work reveals the structural hallmarks of crassviruses and, when combined with comparative genomic analysis, enabled the researchers to assign functions to the majority of the previously uncharacterized proteins involved in virion assembly and infection.