Characterization of a highly pathogenic porcine Teschoviruses 5 emerged in Western China.

Porcine teschovirus (PTV) is a devastating virus that targets the central nervous system and led to great economic losses in Europe between the 1920s and 1960s. Since 1973, PTV variants with lower pathogenicity have been prevalent globally, whereas highly pathogenic PTV strains have rarely emerged. In 2022, diarrhea with high mortality occurred on a pig farm in Gansu China. Virome analysis revealed that PTV was enriched among diarrheal samples. A PTV strain was then isolated and characterized by TEM, IFA, and growth kinetic features. Phylogenetic analyses revealed that the isolate shared an identity of approximately 90% with the most related PTV strain and with various mutant clusters among VP1. Further animal tests demonstrated that the isolate can result in serious respiratory distress, watery diarrhea, paralysis and high mortality in challenged pigs. H&E staining revealed the presence of lymphocyte cells infiltration and hemorrhage in the tissues. Overall, a PTV variant with high mortality was identified in western China, which could result in interstitial pneumonia, hemorrhage, and diarrhea. Although most PTV strains are associated with asymptomatic infection now, the sporadic occurrence of highly pathogenic PTVs is worthy of alarm.