Molecular detection of porcine circovirus (PCV2 and PCV3), torque teno swine virus 1 and 2 (TTSuV1 and TTSuVk2), and histopathological findings in swine organs submitted to regular slaughter in Southeast, Brazil

Abstract

Porcine circovirus 2 and 3 (PCV2 and PCV3) and torque teno sus virus 1 and 2 (TTSuV1 and TTSuVk2) are important pathogens in pig associated with post-weaning mortality, different clinical syndromes in adults (PCVAD), and a decrease of average daily weight gain (PCV2-SI) but little is known about the infection on asymptomatic pigs. The aim of this study was to evaluate the presence of PCV2, PCV3, TTSuV1, and TTSuVk2 in swine organ samples from asymptomatic pigs slaughtered in Espírito Santo State, South-eastern Brazil, through molecular detection and histopathological analysis. Nested PCR showed the presence of PCV2 DNA in 10% (14/140), PCV3 in 13.6% (19/140), TTSuV1 in 12.9% (18/140), and TTSuVk2 in 30% (42/140) of the tissue samples. All four viruses were detected in the lung, kidney, lymph node, and liver. TTSuVk2 was detecded in 30% (42/140), PCV3 in 13.6% (19/140), TTSuV1 in 12.9% (18/140), and PCV2 in 10% (14/140) of the samples. Single infections were observed in 30.7% (43/140), while co-detections in the same tissue occurred in 15.7% (22/140). The most frequent combinations were TTSuV1/TTSuVk2 in 31.8% (7/22), PCV2/TTSuVk2 in 18.1% (4/22), and PCV2/PCV3/TTSuVk2 in 13.6% (3/22). Lymphocyte depletion was associated with TTSuVk2 infection (p = 0.0041) suggesting that TTSuVK2 plays an induction of PMWS-like lymphoid lesions in pigs. The data obtained in this study show that PCV2, PCV3, TTSuV1, and TTSuVk2 are related to infection in asymptomatic animals with different tissue lesions, and the molecular diagnosis for these pathogens should be considered in the sanitary monitoring of herds.