Multiple Layers of Chimerism in a Single-Stranded DNA Virus Discovered by Deep Sequencing

mathis, robert l;

Viruses with single-stranded(ss) DNA genomes infect host sinall three domains of life and include many medically, ecologically, and economically important pathogens. Recently, a new group of ssDNA viruses with chimeric genomes has been discovered through viral meta genomics. These chimeric viruses combine capsid protein genes and replicative protein genes that, respectively, appear to have been inherited from viruses with positive-strand RNA genomes, such as tombusviruses, and ssDNA genomes, such as circoviruses, nanoviruses or geminiviruses. Here, we describe the genome sequence of a new representative of this virus group and reveal an additional layer of chimer is mamong ssDNA viruses. We show that not only do these viruses encompass genes for capsid proteins and replicative proteins that have distinct evolutionary histories, but also the replicative genes themselves are chimeras of functional domains in herited from viruses of different families. Our results under score the importance of horizontal gene transfer in the evolution of ssDNA viruses and the role of genetic recombination in the emergence of novel virus groups