Phylogeny, spatio-temporal phylodynamics and evolutionary scenario of Torque teno sus virus 1 (TTSuV1) and 2 (TTSuV2) in wild boars: fast dispersal and high genetic diversity.

Torque teno sus viruses (TTSuV1-2), members of the newly established family Anelloviridae are considered non-pathogenic emerging viral agents of Suidae species. However, the genetic diversity, phylogeny and evolutionary processes responsible for the emergence and spread of TTSuVs in wild boars remain poorly understood. Here we implemented phylogenetic and evolutionary analyses to address key questions on the genetic diversity, evolutionary scenario and spatio-temporal dynamics of emerging TTSuVs in wild boars of the Western region (Transylvania) of Romania. High levels of genetic diversity of wild boar origin TTSuV1-2 have been found as well as a new TTSuV1 genotype and several new subtypes. Phylogenies suggest that several wild boar viral strains in both TTSuV species are likely to have emerged from a well-defined ancestor approximately 40 (TTSuV1) and 18 (TTSuV2) years ago and showed independent evolutionary trajectories. Bayesian phylogeography showed an intense flow of viral strains throughout the Transylvanian counties possibly related to wild host migrations, facilitating the rapid spread of TTSuVs. The intra-genotype and inter- and intrahost level recombination, intense spatio-temporal viral flow and the positively selected sites found in the ORF2 genes should be considered important driving forces shaping TTSuVs evolution. The first reported rates of nucleotide substitution for porcine anelloviruses, estimated to be 5.29-5.51 × 10(-4)subs site(-1)year(-1), are in line with those measured previously for mammalian ssDNA viruses and RNA viruses. These high evolutionary rates of TTSuVs, independent of recombination, are reflections of adaptive evolution, an important factor in the emergence of novel viral variants which may explain their ability to emerge in Suidae hosts.