A45 Genetic diversity of anelloviruses in the blood virome

The microbiome has an important impact on human health. The microbiome is a complex ecosystem that contains of a wide variety of microorganisms shaped by the immune system, host genetic factors, and the environment. Studies of the human virome have identified a diverse group of viruses in different compartments of the body, including viruses of the Anelloviridae family. These viruses are widespread among the general population. In various clinical conditions an association has been found between the Anelloviridae abundance and the patient’s immune status. However, no pathological consequences have been identified for this viral family. In this study, we analyzed the Anelloviridae diversity in plasma samples of liver transplant recipients. The virome contents of plasma samples from liver transplant recipients were sequenced by next-generation sequencing techniques on an Illumina platform (NextSeq). Complete Anelloviridae ORF1 contigs were extracted from metagenomic data and aligned with 66 RefSeq anellovirus sequences for phylogenetic analysis. The study included 144 plasma samples of 24 liver transplant recipients who had been infected by the hepatitis B virus and developed end-stage liver disease. The identified Anelloviridae viruses belong to the Alphatorquevirus, Betatorquevirus, and Gammatorquevirus genera. In total, we were able to retrieve 142 unique anellovirus contigs that were less than 95 per cent identical on the nucleotide level. A phylogenetic tree was constructed from these contigs with 65 RefSeq sequences retrieved from GenBank. The majority of the identified Anelloviridae sequences were assigned to the Alphatorquevirus genus, which represents the largest group of anelloviruses. We were able to identify a high diversity of Anelloviridae viruses in serum samples of liver transplant recipients. Phylogenetic analysis showed that the majority of anelloviruses belonged to the Alphatorque genus. Future research should focus at elucidating the role of these commensal viruses in both immunocompromised and healthy individuals.