Transfusion Transmitted Virus

TTV, for Transfusion Transmitted Virus or Torque teno virus was first reported in Japan by the research scientist T. Nishizawa. The virus is extremely common even in healthy individuals &mdash; as much as 100% prevalent in some countries, and in approximately 10% of blood donors in the UK and the US. Although it does not appear to cause symptoms of hepatitis on its own, it is often found in patients with liver disease.

TTV's genome is a single-stranded piece of DNA, approximately 3.8 kb in length; it is a non-enveloped virus with a virion of about 40 nm in diameter. While bearing some similarity to members of the group Circoviridae, it lacks sequence homology with any known viruses, and it is believed to be the first known member of a new family of viruses. It is classified under the genus Anellovirus.

Its genome contains 2 large open reading frames, encoding 770 and 202 amino acids, as well as several smaller ORFs.