Exploring the diversity and evolution of tombus-like viruses: phylogenetic analysis, recombination events, and suppressor protein homologs.

Abstract

This study focuses on the phylogenetic analysis of previously unclassified tombus-like viruses, which are characterized by the presence of homologs of the suppressor protein p19. The primary objectives of this research were to investigate the evolutionary relationships among these viruses and to explore the impact of suppressor proteins and recombination events on their evolution. A dataset comprising 94 viral sequences was analyzed to achieve these goals. The phylogenetic analysis revealed the presence of two distinct clusters within the tombus-like virus group. One cluster consisted of viruses that encoded p19-like RNA suppressors, while the other cluster comprised viruses encoding p14-like suppressors. Based on these findings, we propose the classification of PGT-pt108 as an isolate of carnation Italian ringspot virus (CIRV), and both Tombusviridae sp. s48-k141_139792 and Tombusviridae sp. s51-k141_185213 as isolates of tomato bushy stunt virus (TBSV). Furthermore, this study suggests the establishment of two new genera within the family Tombusviridae, based on the observed divergence and distinct characteristics of these tombus-like viruses. Through the analysis of recombination events, we provide insights into the interspecies movement of CIRV, which is reflected in its phylogenetic positioning. This research contributes to our understanding of the evolutionary dynamics and classification of tombus-like viruses, shedding light on the role of suppressor proteins and recombination events in their evolution and interspecies transmission.