Characterization of a highly divergent TT virus genome

A novel TT virus (TTV)-like DNA sequence was detected in the serum of a pat ient (PM) with acute non-A-E hepatitis. The full-length genome sequence, re ferred to here as PM virus (PMV), was obtained and its relationship to othe r full or near full-length TTV sequences examined. Although it shares a com mon genomic arrangement and short conserved regions, the majority of the ge nome is extremely divergent, displaying an average genetic distance of 0.60 from all other TTV sequences. By comparing PMV with TTV genomes representi ng the most divergent types so far described, six major groups can be disti nguished. The level of genetic diversity seen between these genomes is high er than would be expected within a single virus species. Indeed, PMV could be considered the prototype of an independent taxonomic group within the Ci rcoviridae family. A genoprevalence study of sera from blood donors and pat ients with acute hepatitis suggests that PMV is rare.