Effect of coinfection with genogroup 1 porcine torque teno virus on porcine circovirus type 2-associated postweaning multisystemic wasting syndrome in gnotobiotic pigs

Objective-To determine whether genogroup 1 porcine torque teno virus (g1-TTV) can potentiate clinical disease associated with porcine circovirus type 2 (PCV2). Sample population-33 gnotobiotic baby pigs. Procedures-Pigs were allocated into 7 groups: group A, 5 uninoculated control pigs from 3 litters; group B, 4 pigs oronasally inoculated with PCV2 alone;, group C, 4 pigs inoculated IP with first-passage g1-TTV alone-, group D, 4 pigs inoculated IP with fourth-passage g1-TTV alone-, group E, 6 pigs inoculated IP with first-passage g1-TTV and then oronasally inoculated with PCV2 7 days later; group F, 6 pigs inoculated IP with fourth-passage g1-TTV and then inoculated oronasally with PCV2 7 days later-, and group G, 4 pigs inoculated oronasally with PCV2 and then inoculated IP with fourth-passage g1-TTV 7 days later. Results-6 of 12 pigs inoculated with g1-TTV prior to PCV2 developed acute onset of post-weaning multisystemic wasting syndrome (PMWS). None of the pigs inoculated with g1-TTV alone or PCV2 alone or that were challenge exposed to g1-TTV after establishment of infection with PCV2 developed clinical illness. Uninoculated control pigs remained healthy. Conclusions and Clinical Relevance-These data implicated g1-TTV as another viral infection that facilitates PCV2-induced PMWS. This raises the possibility that torque teno viruses in swine may contribute to disease expression currently associated with only a single infectious agent. (Am J Vet Res 2008;69:1608-1614)