Análise extensiva da virosfera e seus hospedeiros: avançando na sistemática, genômica e transcriptômica de vírus gigantes

Abstract

Viruses are the most abundant and diverse biological entities on the planet, forming a virosphere. They are associated to organisms from all domains of life, but it is still not clear how this network is connected. Here, by performing an extensive meta-analyses it was possible to obtain a wide view about this network, as well as the distribution of different group of viruses on the planet. The data presented here revealed an anthropocentric virosphere, wherein most of the known viruses are associated to human being and species of medical, economical or biotechnological interest. Moreover, it was possible to identify at least 320 viral species with representatives able to infect humans. Among the viruses that are not associated as etiological agents of infections in humans, giant viruses are noteworthy by their genomic and structural complexity. Much has been debated about their origin, evolution and classification, and new analyzes are needed to improve viral systematics. Phylogenetic reconstructions using different strategies to obtain homologous sequences led to divergent conclusions about the origin of mimiviruses and tupanviruses, and it is not possible to define this debate based on analyzes of only one or a few genes. When reviewing the characteristics of the tupanvirus, a series of particularities was compiled to justify the creation of a new taxonomic group to properly classify them, the genus "Tupanvirus". In addition, to better understand the biology and evolution of giant viruses, genomic and transcriptomic analyzes must be advanced. In this sense, the analysis of the genome of the Brazilian cedratvirus IHUMI indicated the existence of a new lineage of cedratvirus. The new isolate has smaller viral particles than the other viruses in the group, besides presenting a shorter and asyntenic genome. Finally, data analysis from the RNA sequencing of marseillevirus confirmed the existence of the genes previously predicted and revealed a temporal profile of gene transcription for these viruses. This work provided, for the first time, a global view of the virosphere and its hosts, besides advancing in different aspects in the study of the giant viruses, especially in the systematics, genomics and transcriptomics of different viral groups.