Detection of Torque teno virus DNA in exhaled breath by polymerase chain reaction

To determine whether exhaled breath contains Torque teno virus (TTV) or not, we tested exhaled breath condensate (EBC) samples by semi-nested PCR assay. We detected TTV DNA in 35% (7/20) of EBC samples collected from the mouth of one of the authors, demonstrating that TTV DNA is excreted in exhaled breath with moderate frequency. TTV DNA was detected also in oral EBC samples from 4 of 6 other authors, indicating that TTV DNA excretion in exhaled breath is not an exception but rather a common phenomenon. Furthermore, the same assay could amplify TTV DNA from room air condensate (RAC) samples collected at distances of 20 and 40cm from a human face with 40 (8/20) and 35% (7/20) positive rates, respectively. TTV transmission has been reported to occur during infancy. These distances seem equivalent to that between an infant and its household members while caring for the infant. Taken together, it seems that exhaled breath is one of the possible transmission routes of TTV. We also detected TTV DNA in 25% (10/40) of RAC samples collected at a distance of more than 180cm from any human face, suggesting the risk of airborne infection with TTV in a room.