[1] In silico comparative genomics and taxonomic analysis have found that crAss-like phages represent a highly abundant and diverse family of viruses.

[4] Crassviruses used to be part of the abolished family of podoviruses, possessing short non-contractile tails and icosahedral capsids.

[3][2][7][8] The crAss (cross-assembly) software used to discover the first crAss-like phage, p-crAssphage (prototypical-crAssphage), relies on cross assembling reads from multiple metagenomes obtained from the same environment.

Several cross-contigs consisting of unknown reads were identified in all twelve individuals and through re-assembly techniques, the p-crAssphage genome was re-constructed.

Using co-occurrence analysis and CRISPR spacer similarities, the phage was predicted to infect Bacteroidota bacteria[1] which are dominant members of the gut microbiome in most individuals.

[10] The crAss-like phage bacteriophage family is considered highly diverse and consists of four subfamilies- alpha, beta, delta, and gamma- and ten genera within the subfamilies.

[12][3] Despite the genetic evidence of certain lifestyles, in vitro studies of crAss-like phage replication strategies have yielded inconclusive results.

It was hypothesized that crAss001 uses a lesser-known replication strategy like pseudolysogeny or a carrier state,[4] but a recent study has found evidence that the host is at least partially responsible for the stable co-existence through phase variation.

[14] When crAss002 is inoculated into a culture of B. xylanisolvens, the phage takes several days of co-culturing to begin propagating after which it maintains a stable and relatively high titer.

Despite the crAss001 and crAss002 titers increasing after infection, the cell counts of the bacterial community members were seemingly unaffected by the phage presence.

[22] Additionally, there is strong evidence that specific crAss-like phage can be transmitted between humans via fecal microbial transplants (FMTs).