Detection of Torque Teno Sus Virus Types 1 and 2 by Nested Polymerase Chain Reaction in Sera of Sows at Parturition and of Their Newborn Piglets Immediately after Birth without Suckling Colostrum, and at 24 hr after Suckling Colostrum

Abstract

This study was performed first to clarify the sow-to-fetus transmission pathway of the Torque teno sus virus (TTSuV) types 1 (TTSuV1) and 2 (TTSuV2). For this purpose, detection of TTSuV1 and TTSuV2 (TTSuVs) in sera of 6 sows (Sows 1–6) at parturition and in sera of their newborn piglets immediately after birth without suckling colostrum was performed by nested polymerase chain reaction (nPCR). These sows were bred using semen that had tested negative for TTSuVs. In a TTSuV1- and TTSuV2-positive sow (Sow 1), TTSuV1 and TTSuV2 were detected in 4 and 5 of 12 newborn littermates, respectively. In a TTSuV1-positive sow (Sow 2), TTSuV1 was detected in 1 of 8 newborn littermates. In 4 TTSuV1- and TTSuV2-negative sows (Sows 3–6), TTSuV1 was detected in 6 out of the 25 newborn piglets of 3 sows (Sows 3–5), while no TTSuVs were detected in 13 piglets of 1 sow (Sow 6). Second, to investigate the possibility of sow-to-piglet transmission pathway of TTSuV via colostrum, TTSuV1 and TTSuV2 in sera of 12 newborn piglets from Sows 1–3 were examined by nPCR. Immediately after birth without suckling colostrums, TTSuV1 and TTSuV2 were not detected in 10 and 8 of 12 newborn piglets respectively; however, at 24 hr after suckling colostrum, TTSuV1 was detected in 6 piglets, but TTSuV2 was not detected in any piglets. These results confirmed the existence of sow-to-fetus transmission pathway of TTSuV during normal pregnancy, and suggested a possibility of sow-to-piglet transmission of TTSuV via colostrum.