Real-time PCR study of the infection dynamics of Torque teno sus viruses in naturally infected pigs from nursery to slaughterhouse

Although torque teno viruses are frequently detected in humans and animals the pathogenicity and virulence of these viruses are currently unknown, and little information on the dynamics of infection is available. In this study, 24 pigs were monitored from 2 weeks of age to slaughter to determine the natural infection dynamics of Torque teno sus virus (TTSuV) species 1 (TTSuV1) and species 2 (TTSuV2). Plasma and fecal material were collected at 2, 8 and 18 weeks of age and between 22 and 29 weeks of age, while organs and tissues were collected at slaughter. iruses were found to disseminate very quickly within the herd. At 8 weeks, TTSuV2 and TTSuV1 were observed at rates of 88% and 58%, respectively, and peak excretion occurred at 18 weeks. Furthermore, TTSuV DNA was detected in the plasma of between 96% and 100% of the animals, and viremia was maintained at a viral load between 5 × 104 and 5 × 106 copies/mL until slaughter. All tested organs and tissues contained TTSuVs in amounts ranging from 103 to 108 copies/g; the highest concentration of viruses was found in the liver. This study did not demonstrate any association with disease, despite the high prevalence of TTSuVs.