In case of TTSuV1, MDA against TTSuV1 ORF1-A protein was commonly observed in piglets. The antibody profile indicates that MDA adversely affected the development of the humoral immune response against TTSuV1, in the sense that evidence of seroconversion took place later in time compared to TTSuV1 MDA-. This result should not be considered surprising since the inhibitory effect of MDA on the development of the humoral immune response upon infection has been well documented for other swine pathogens, as is the case of Erysipelothrix rhusiopathiae, H1N1 influenza SR1078 or even in case of other ssDNA virus like PCV2. In these examples, development of the host immune response following vaccination or experimental infection was significantly influenced by the MDA status of the piglet at the time of vaccination or infection ( Fraile et al., 2012 and Loeffen et al., 2003). In conclusion, the current study was aimed to develop specific immune assays to detect antibodies against two TTSuV species. Almost all tested pigs developed antibodies against both viruses along their productive life (from nursery to slaughter), but presence of antibodies at early ages (4 week-old pigs) were mainly detected for TTSuV1. This difference raised the question if lack of MDAs could play a role during the development of diseases linked to TTSuV2.
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