title: Multiple models of porcine teschovirus pathogenesis in endemically infected pigs.
abstract: Porcine teschoviruses (PTVs) belong to the genus Teschovirus within the family Picornaviridae. PTVs are universal contaminants in pig herds in endemic and multi-infection status. To further the understanding of PTV pathogenesis in endemically infected pigs, a set of samples was studied by real time reverse transcription PCR (qRT-PCR) to quantitate viral loads in tissues and by in situ hybridization (ISH) to locate PTV signals in target cells, both targeting the 5'-NTR. cRNA of PTV-1 and PTV-7, in vitro transcribed from cloned fragments of 5'-NTR of 2 viruses, was used to construct standard curves and to run parallel in qRT-PCR, which had detection limits of 10(1) copies/per reaction, with a linearity in between 10(1) and 10(7) copies/per reaction and correlation coefficients of 0.997-0.9988. The qRT-PCR specifically amplified RNA from PTV-1 to -11, while excluding those of Sapelovirus, PEV-9 and PEV-10. Inguinal lymph node (LN) had the highest viral load of all (assuming 100%), followed by ileac LN (89-91%), tonsil (66-68%), ileum (59-60%), spleen (38-40%), and kidney (30-31%), with the least in brain (22.9%) of the inguinal LN. The 22.9% load in brain was higher than that anticipated from a simple fecal-oral-viremia operative model. The results suggested in addition that intranasal infection and retrograding axonal infection from the tonsils were equally operative and significant. ISH revealed PTV signals in a wider variety of tissue cell types than before. PTV signals were noted most impressively in neurons of the cerebral cortex and hippocampus and in the dark zone of the germinal center and adjacent paracortex of regional LN. Multiple operative models indicated that PTVs seemed to have no difficulty invading the brain. The key to whether encephalitis would ensue resided in the animal's immune status and topographic differences of neurons' susceptibilities to PTVs. When common co-infected agents are present, as is typical in the field, PTVs may synergize in causing diseases.
authors.affiliation: Animal Health Research Institute, No. 376, Chung Cheng Road, Tamsui, New Taipei City 25158, Taiwan; School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Shu-Chun
authors.initials: SC
authors.lastname: Chiu
authors.affiliation: School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Chih-Lin
authors.initials: CL
authors.lastname: Yang
authors.affiliation: School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Ya-Mei
authors.initials: YM
authors.lastname: Chen
authors.affiliation: Animal Health Research Institute, No. 376, Chung Cheng Road, Tamsui, New Taipei City 25158, Taiwan; School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Shu-Chia
authors.initials: SC
authors.lastname: Hu
authors.affiliation: School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Kuo-Chao
authors.initials: KC
authors.lastname: Chiu
authors.affiliation: School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Yi-Chien
authors.initials: YC
authors.lastname: Lin
authors.affiliation: Animal Health Research Institute, No. 376, Chung Cheng Road, Tamsui, New Taipei City 25158, Taiwan.
authors.forename: Chia-Yi
authors.initials: CY
authors.lastname: Chang
authors.affiliation: School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan. Electronic address: fiwangvm@ntu.edu.tw.
authors.forename: Fun-In
authors.initials: FI
authors.lastname: Wang
mesh_terms: D000818:Animals; D019353:Endemic Diseases / Q000662:veterinary*; D005243:Feces / Q000821:virology; D010850:Picornaviridae Infections / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000592:standards; D012680:Sensitivity and Specificity; D013552:Swine; D013553:Swine Diseases / Q000473:pathology* / Q000821:virology*; D052700:Teschovirus / Q000472:pathogenicity*; D019562:Viral Load
keywords: In situ hybridization; Pathogenesis; Porcine teschovirus; Viral load; qRT-PCR