CrAssphage


crAssphage is a bacteriophage that was discovered in 2014 by computational analysis of publicly accessible scientific data on human faecal metagenomes. Its circular DNA genome is around 97 kbp in size and contains 80 predicted open reading frames, and the sequence is commonly found in human faecal samples. At its time of discovery, the virus was predicted to infect bacteria of the phylum Bacteroidetes that are common in the intestinal tract of many animals including humans. Since then, the bacteriophage has been isolated in vitro and confirmed to infect Bacteroides intestinalis. Based on analysis of metagenomics data, crAssphage sequences have been identified in about half of all sampled humans. The virus was named after the crAss software that was used to find the viral genome. CrAssphage is possibly the first organism to be named after a computer program for promotional purposes.
While crAssphage did not have any known relatives when it was discovered in 2014, a range of related viruses were discovered in 2017. Based on a screen of related sequences in public nucleotide databases and phylogenetic analysis, it was concluded that crAssphage may be part of an expansive bacteriophage family that is found in a range of environments including human gut and feces, termite gut, terrestrial/groundwater environments, soda lake, marine sediment, and plant root environments.
There is no indication that crAssphage is involved in human health or disease. The virus may outperform indicator bacteria as a marker for human faecal contamination.