José Manuel Cuevas, María Cebriá

This doctoral thesis, directed by José Manuel Cuevas, allows us to know the composition of the virome of the plasma of human blood donors. Part of the results have been published in the journals Scientific Reports and Viruses. The thesis was defended on July 22, 2022.

The development of viromics has driven the discovery of a notable number of new virus sequences, which has allowed us to understand the composition of viral communities in multiple environments, including the human body. In this thesis, titled “Characterization of the virome in plasma from blood donors”, plasma from samples from the Transfusion Center of the Valencian Community has been studied. To this end, a protocol for enriching the viral fraction has been developed along with a subsequent bioinformatics analysis of the data obtained after sequencing. In the taxonomic classification of the samples, it has been seen that the majority of the readings obtained belong to the Anelloviridae family. Phylogenetic analyzes carried out using the coding sequence of these genomes have revealed enormous diversity and a considerable number of potentially new species have been observed. Furthermore, a small fraction of the samples have been analyzed on an individual scale, which has made it possible to observe that each individual presents his or her personal and distinctive set of anelloviruses. On the other hand, in a much smaller percentage due to its low prevalence, some samples have been detected that presented readings of the human pegivirus, which belongs to the Pegivirus genus and, in turn, to the Flaviviridae family. Human anelloviruses and pegiviruses are considered orphan viruses, because they do not have any associated disease. Therefore, studies of the plasma virome can be used to try to understand the role of these viruses on the health and disease of individuals.

María Cebriá carried out her doctoral research under the supervision of José Manuel Cuevas, professor of Genetics at the University of Valencia at the Institute of Integrative Systems Biology I2SysBio (UV-CSIC). The qualifying panel was made up of Mireia Coscollà (I2SysBio), Xavier López Labrador (Fisabio), and Antonio Alcamí (CBM Severo Ochoa, CSIC-UAM), who rated the thesis as outstanding.