Infectivity of recombinant Torque teno sus virus 1 in pigs coinfected with swine influenza virus.

Abstract

Torque teno viruses (TTVs) are small non-enveloped DNA viruses that are ubiquitous among mammalian species. Although their pathogenic potential remains uncertain, TTVs can modulate host immunity and potentiate coinfecting pathogens or comorbid conditions. Progress in understanding TTV biology has been constrained by the absence of robustandexperimental systems. To address these limitations, we investigated the infectivity of a recombinant swine TTV [Torque teno sus virus 1 (TTSuV1)] generated with a reverse genetics system in a snatch-farrowed piglet model. Additionally, we evaluated the impact of TTSuV1 coinfection on the pathogenesis and replication dynamics of swine influenza virus (SIV). Infection of piglets with the rescued TTSuV1 induced seroconversion and lymphopenia. Early infection was associated with reduced lymphocyte proliferative responses to mitogens and diminished or absent recall responses to viral antigens. TTSuV1 antigen was detected within immune cell populations by flow cytometry. Contrary to expectations, prior TTSuV1 infection did not significantly exacerbate SIV-associated clinical signs or pulmonary lesions. The use of a snatch-farrowed piglet model in combination with recombinant TTSuV1 derived from reverse genetics provides a controlled system for investigating TTV-host interactions. This approach represents a valuable tool for advancing mechanistic studies of TTV biology and its role in modulating coinfections.