Multiple models of porcine teschovirus pathogenesis in endemically infected pigs
Journal
Veterinary Microbiology
Journal Volume
168
Journal Issue
1
Pages
69-77
Date Issued
2014
Author(s)
Chiu, Shu-Chun
Yang, Chih-Lin
Hu, Shu-Chia
Chiu, Kuo-Chao
Lin, Yi-Chien
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 101 copies/per reaction, with a linearity in between 101 and 107 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. © 2013 Elsevier B.V.
Subjects
In situ hybridization; Pathogenesis; Porcine teschovirus; QRT-PCR; Viral load
Other Subjects
locked nucleic acid; animal experiment; animal model; article; brain cortex; controlled study; encephalitis; endemic disease; germinal center; hippocampus; immune status; in situ hybridization; in vitro study; inguinal lymph node; kidney distal tubule; nerve cell; nonhuman; pathogenesis; real time polymerase chain reaction; reverse transcription polymerase chain reaction; target cell; Teschen disease; Teschovirus; viremia; virus entry; virus load; virus shedding; Animalia; Peru tomato mosaic virus; Picornaviridae; Porcine teschovirus; Suidae; Sus; Teschovirus; In situ hybridization; Pathogenesis; Porcine teschovirus; qRT-PCR; Viral load; Animals; Endemic Diseases; Feces; Picornaviridae Infections; Reproducibility of Results; Reverse Transcriptase Polymerase Chain Reaction; Sensitivity and Specificity; Swine; Swine Diseases; Teschovirus; Viral Load
Type
journal article