Molecular Epidemiology and Pathogenicity Evaluation of Porcine Teschovirus in Tibetan Pigs on the Qinghai-Tibet Plateau of China.

چکیده اصلی

Porcine teschovirus (PTV) is the causative agent of porcine diarrhea and multisystem disorder and poses a global threat to the health of domestic pigs. However, its epidemic and pathogenic characteristics in Tibetan pigs, which are a unique indigenous breed in the Qinghai-Tibet Plateau of China, remain largely unexplored. Here, we conducted a comprehensive investigation during 2024-2025, in which 303 diarrheic fecal samples were collected from 21 farms across eight counties in Ganzi Tibetan Autonomous Prefecture, with an average altitude of 3433 m. RT-PCR testing identified 141 PTV-positive samples, yielding a high positivity rate of 46.5% (141/303). From these positives, 27 VP1 sequences were cloned and sequenced; phylogenetic analysis revealed that 16 strains belonged to Teschovirus A, three strains were divided into Teschovirus B, and three strains formed the interspecies recombinant genotypes (PTV-15/16). Interestingly, five novel strains were classified as undefined genotypes, indicating an extensive genetic diversity among PTV strains circulating in Tibetan pigs. Furthermore, a PTV strain, designated PTV-SCgz-01, was successfully isolated in PK-15 cells, with a near-complete genomic sequence of 7081 nucleotides. Phylogenetic analysis based on the polyprotein and the VP1 genes indicated that it belonged to genotype PTV-4, whereas recombination analysis revealed that PTV-SCgz-01 is a natural recombinant with parental strains derived from HNMY (PTV-4) and China/SWU-ZG2/2018 (PTV-6). Experimental infection of 17-day-old Tibetan piglets demonstrated that this isolate induces severe watery diarrhea. Notably, the virus also caused severe pulmonary hemorrhage and mild cerebral hyperemia with neuronal degeneration, and it had a high mortality rate (40%), suggesting that strain PTV-SCgz-01 has strong pathogenic potential for 17-day-old Tibetan piglets. Our findings provide a more comprehensive molecular epidemiology of PTVs in Tibetan pigs and underscore the need for viral surveillance and control in this unique pig population.

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