Serological profile of Torque teno sus virus species 1 ( TTSuV 1 ) in pigs and 1 antigenic relationships between two TTSuV 1 genotypes ( 1 a and 1 b ) ,

24 The family Anelloviridae includes human and animal Torque teno viruses (TTV) with extensive 25 genetic diversity. The antigenic diversity among anelloviruses has never been assessed. Using 26 Torque teno sus virus (TTSuV) as a model, we describe here the first investigation on antigenic 27 relationships among different anelloviruses. Using the TTSuV1a or TTSuV1b ELISA based on 28 the respective putative ORF1 capsid antigen and TTSuV1-specific real-time PCR, the combined 29 serological and virological profile of TTSuV1 infection in pigs was determined and compared 30 with that of TTSuV2. TTSuV1 is likely not associated with porcine circovirus associated disease 31 (PCVAD) since both the viral loads and antibody levels were not different between affected and 32 unaffected pigs and since there was no synergistic effect of concurrent PCV2/TTSuV1 infections. 33 We did observe a higher correlation of IgG antibody levels between anti-TTSuV1a and 34 TTSuV1b than between anti-TTSuV1a or -1b and anti-TTSuV2 in these sera, implying potential 35 antigenic cross-reactivity. To confirm this, rabbit antisera against the putative capsid proteins of 36 TTSuV1a, TTSuV1b or TTSuV2 were generated and the antigenic relationships among these 37 TTSuVs were analyzed by ELISA and by IFA using PK-15 cells transfected with one of the 38 three TTSuV ORF1 constructs. Results demonstrate antigenic cross-reactivity between the two 39 genotypes, TTSuV1a and TTSuV1b, but not between the two species, TTSuV1a or 1b and 40 TTSuV2. Furthermore, an anti-genogroup 1 human TTV antiserum did not react with any of the 41 three TTSuV antigens. Results have important implications for understanding the diversity of 42 anelloviruses as well as for classification and vaccine development of TTSuVs. 43