Anelloviruses are a group of single-stranded
circular DNA viruses infecting several vertebrate species. Four species have been found to infect swine, namely Torque teno sus virus (TTSuV) 1a and 1b (TTSuV1a, TTSuV1b; genus Iotatorquevirus), TTSuVk2a and TTSuVk2b (genus Kappatorquevirus). TTSuV
infection in pigs is distributed worldwide, and is characterized by a persistent
viremia. However, the real impact, if any, on the pig health is still under debate. In the present study, the impact of pig immunization on TTSuVk2a loads was evaluated. For this, three-week old conventional pigs were primed with
DNA vaccines encoding the ORF2 gene and the ORF1-A, ORF1-B, and ORF1-C splicing variants and boosted with purified ORF1-A and ORF2
Escherichia coli proteins, while another group served as unvaccinated control animals, and the viral load dynamics during natural
infection was observed. Immunization led to delayed onset of TTSuVk2a
infection and at the end of the study when the animals were 15 weeks of age, a number of animals in the immunized group had cleared the TTSuVk2a
viremia, which was not the case in the control group. This study demonstrated for the first time that TTSuV
viremia can be controlled by a combined
DNA and
protein immunization, especially apparent two weeks after the first
DNA immunization before seroconversion was observed. Further studies are needed to understand the mechanisms behind this and its impact for pig producers.