title: The pathogenic role of torque teno sus virus 1 and 2 and their correlations with various viral pathogens and host immunocytes in wasting pigs.
abstract: The pathogenic role of torque teno sus virus (TTSuV) in swine is controversial among different studies. The present study intended to evaluate the potential pathogenicity of TTSuV based on its correlations with the histopathological changes, various common concurrently infected viral pathogens including porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), and porcine parvovirus (PPV), as well as changes in the distribution and population of host immunocytes such as B lymphocytes, T lymphocytes, and macrophages by using the superficial inguinal lymph nodes (siLNs) of wasting pigs. A tissue microarray consisting of 270 available siLNs collected from 262 clinically wasting and 8 healthy pigs, respectively, were used for the detection of TTSuV1, TTSuV2, PCV2, PRRSV, and PPV by either in situ hybridization (ISH) or immunohistochemical (IHC) staining, and for the detection of various subsets of immunocytes by IHC staining with monoclonal antibodies to CD3, CD79a, and lysozyme. The slides were then subject to digital scanning followed by a semi-quantitative positive pixel evaluation for further statistical analysis. Although a high prevalence of TTSuV1 and/or TTSuV2 infection was noted in both wasting and healthy pigs, the wasting pigs had a significantly higher intensity in both TTSuV1 and TTSuV2 ISH-positive signals than healthy ones did. In the wasting pigs, a significant positive correlation in the tissue viral load was noted between TTSuV1 and TTSuV2 and between TTSuV2 and PCV2, but not between TTSuV1 and PCV2. Conversely, a significant negative correlation in the tissue viral load was revealed between TTSuV2, but not TTSuV1, and PRRSV. The tissue viral load of TTSuV1 was significantly correlated with B cell hyperplasia, while the tissue viral load of TTSuV2 was significantly correlated with increased macrophage population. The ISH positivity of TTSuV2 was significantly correlated with lymphoid depletion and granulomatous inflammation, which are the characteristic histopathological findings in postweaning multisystemic wasting syndrome-affected pigs. These findings suggest that both TTSuV species may have the potential involving the development of porcine circovirus-associated lymphoid lesions via alternating the host immune system.
authors.affiliation: Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei 10617, Taiwan, ROC; Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Yao
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei 10617, Taiwan, ROC.
authors.forename: Chun-Ming
authors.initials: CM
authors.lastname: Lin
authors.affiliation: Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei 10617, Taiwan, ROC.
authors.forename: Chian-Ren
authors.initials: CR
authors.lastname: Jeng
authors.affiliation: Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei 10617, Taiwan, ROC.
authors.forename: Hui-Wen
authors.initials: HW
authors.lastname: Chang
authors.affiliation: Department of Veterinary Medicine, National Chiayi University, Chiayi 60054, Taiwan, ROC. Electronic address: ccchang@mail.ncyu.edu.tw.
authors.forename: Chih-Cheng
authors.initials: CC
authors.lastname: Chang
authors.affiliation: Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei 10617, Taiwan, ROC. Electronic address: pang@ntu.edu.tw.
authors.forename: Victor Fei
authors.initials: VF
authors.lastname: Pang
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D018173:Circoviridae Infections / Q000821:virology; D017925:Circovirus / Q000472:pathogenicity; D060085:Coinfection / Q000821:virology; D004266:DNA Virus Infections / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D005260:Female; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007249:Inflammation / Q000276:immunology / Q000821:virology; D008198:Lymph Nodes / Q000473:pathology; D008264:Macrophages / Q000276:immunology; D008297:Male; D028323:Parvovirus, Porcine / Q000472:pathogenicity; D019316:Porcine respiratory and reproductive syndrome virus / Q000472:pathogenicity; D013552:Swine; D013553:Swine Diseases / Q000276:immunology* / Q000821:virology; D013601:T-Lymphocytes / Q000276:immunology; D046888:Tissue Array Analysis; D022783:Torque teno virus / Q000472:pathogenicity*; D019562:Viral Load; D019282:Wasting Syndrome / Q000276:immunology / Q000662:veterinary* / Q000821:virology
keywords: In situ hybridization (ISH); Porcine circovirus type 2 (PCV2); Superficial inguinal lymph node (siLN); Torque teno sus virus (TTSuV); Wasting pig