Evaluation of the effects of porcine genogroup 1 torque teno virus in gnotobiotic swine

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Objective</jats:bold>—To determine whether porcine genogroup 1 torque teno virus (g1-TTV) can infect and cause disease in gnotobiotic swine.</jats:p> <jats:p><jats:bold>Sample Population</jats:bold>—20 conventional baby pigs and 46 gnotobiotic baby pigs.</jats:p> <jats:p><jats:bold>Procedures</jats:bold>—Porcine g1-TTV was transmitted from conventional swine to gnotobiotic pigs via pooled leukocyte-rich plasmas (n = 18) that had positive results for g1-TTV DNA. Bone marrow–liver homogenates that had positive results for torque teno virus (TTV) were used in 4 serial passages in gnotobiotic pigs (2 pigs/passage). A pathogenesis experiment was conducted with in vivo passages of g1-TTV in various groups of gnotobiotic pigs.</jats:p> <jats:p><jats:bold>Results</jats:bold>—All g1-TTV inoculated pigs had no clinical signs but developed interstitial pneumonia, transient thymic atrophy, membranous glomerulonephropathy, and modest lymphocytic to histiocytic infiltrates in the liver after inoculation with the TTV-containing tissue homogenate; these changes were not detected in uninoculated control pigs or pigs injected with tissue homogenate devoid of TTV DNAs. In situ hybridization was used to identify g1-TTV DNAs in bone marrow mononuclear cells.</jats:p> <jats:p><jats:bold>Conclusions and Clinical Relevance</jats:bold>—Analysis of these data revealed that porcine g1-TTV was readily transmitted to TTV-naïve swine and that infection was associated with characteristic pathologic changes in gnotobiotic pigs inoculated with g1-TTV. Thus, g1-TTV could be an unrecognized pathogenic viral infectious agent of swine. This indicated a directly associated induction of lesions attributable to TTV infection in swine for a virus of the genus <jats:italic>Anellovirus</jats:italic>.</jats:p>