Abstract
We report on the prevalence, infection dynamics, and retrospective study of swine torque teno virus (TTV) in pig herds in Tochigi Prefecture. The detection of TTV1 and TTV2 from pig serum was performed with the PCR method using primer pairs specific for each genogroup. A total of 201 sera from 21 farms in 2009 were examined, and the prevalence rates of TTV1 and TTV2 were 77.6% and 56.2%, respectively. In the piglets, infection rates of TTV1 and TTV2 showed a tendency to increase with each month, with the highest percentages at 5 months old (97.7%) and 3 months old (91.7%), respectively. In sows, TTV1 was consistently more prevalent than TTV2. No relationship between the prevalence of TTV infection and herd size, general health, or biosecurity status was observed for the three farms studied for infection dynamics. A retrospective study revealed that TTVs were already widespread in 1995, suggesting that the virus was previously introduced into the pig population in Tochigi Prefecture.
