Molecular Serotyping of the Porcine Teschoviruses in Endemically Infected Pigs
Date Issued
2015
Date
2015
Author(s)
Kuo, Yi-Ching
Abstract
Porcine teschoviruses (PTVs) is a non-enveloped, spherical, positive-sense, single-stranded RNA virus, which belong to genus Teschovirus within the family Picornaviridae. Up to date, PTVs are reclassified into 13 serotypes that are associated with a variety of clinical signs and prominent with polioencephalomyelitis and diarrhea. Two epidemic outbreaks of PTV-1 occurred in Taiwan, one in 2000 and a second in 2004, causing severe economic loss. The enzootic status is now confirmed in swine herds in Taiwan. Previous study has demonstrated at least 5 different serotypes of PTV (PTV-1, -4, -6, -7, -11) existing in Taiwan, and PTV-7 and -6 are the most common serotypes. The aim of this study was to investigate the wider variety of serotypes of PTV by introducing a set of newly designed primer, based on the sequence of VP1 outer capsid gene presented in the feces, plasma, urine, nasal swab, and solid samples in naturally infected piglets. Samples were collected from 7 clinically healthy and 21 culled piglets of 7 different herds. The PTV infections were screened by the published primers to amplify highly conserved 5’NTR region using RT-PCR followed by nested PCR. The PTV detection rate was 100% (28/28) by heads. Out of 217/280 PTV-positive samples the most common detected sample was feces (96%, 27/28), and followed by in decreasing order ileum, tonsil, and nasal swab (93%, 26/28), plasma (86%, 24/28), inguinal LN and urine (both were 79%, 22/28), bladder (64%, 18/28), spleen (57%, 16/28), and kidney (10%, 10/28). VP1 region was successfully amplified, by the newly designed primers, out of 63/217 (29%) pan-PTV nested PCR-positive samples, sequenced, and phylogenetic tree constructed. All 28 piglets had at least one serotype existed, and a total of 5 serotypes of PTV-2, PTV-4, PTV-5, PTV-6, and PTV-10, were identified from 28 piglets. The most common serotype was PTV-10 (36/63, 57%) and the 2nd one was PTV-2 (14/63, 22%). In 14/28 (50%) heads had at least two serotypes identified in the same animals but in different samples. In 2/7 herds, four PTV serotype co-circulated. In conclusion, this study confirms the enzootic and contaminated status of swine herds, combined with previous study at least 8 serotypes of PTV, namely PTV-1、-2、-4、-5、-6、-7、-10、-11 are identified. In particular PTV-10 is found shed in the urine of 3 piglets from 3 separate herds, consistent with the multiple models of PTV pathogenesis. Urine makes solid feces into semisolid slurry thus enhancing the exposure of piglets to PTV.
Subjects
teschovirus
serotyping
RT-PCR
SDGs
Type
thesis
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