Torque teno sus virus 1 and 2 distribution in tissues of porcine circovirus type 2-systemic disease affected and age-matched healthy pigs.

The present work was aimed to investigate the torque teno sus virus 1 and 2 (TTSuV1 and 2) loads of different tissues of pigs affected by porcine circovirus type 2 (PCV2)-systemic disease (PCV2-SD) and healthy age-matched ones. A total of 20 pigs (10 healthy and 10 diagnosed as PCV2-SD) were chosen for the study. From each pig, a total of 7 tissues were analyzed, including lung, kidney, liver, ileum, bone marrow, and mesenteric and mediastinal lymph nodes. TTSuV 1 and 2 were quantified by means of species-specific real time quantitative PCR methods. Both TTSuVs were distributed systemically. Results showed the highest loads for TTSuV2 in tissues from diseased pigs. The highest TTSuV1 DNA load was found in bone marrow, lung, and liver, while it was in bone marrow, mediastinal lymph node and liver for TTSuV2. Bone marrow was the tissue with the highest viral DNA burden for both TTSuV species. Overall, statistically significant differences were observed in viral DNA load, with TTSuV2 showing higher loads than TTSuV1 (p<0.05). Also, tissues from PCVD-SD affected pigs showed higher TTSuV2 loads than tissues of the healthy group (p<0.05). It was concluded that both TTSuVs had a wide tissue distribution all over the body, with differential load comparing diseased versus healthy pigs. It is likely that other tissues not included in this study would also be infected by TTSuVs.