The prevalence of porcine teschovirus in the pig population in northeast of China

The prevalence of porcine teschovirus (PTV) in swine herds in northeast China was investigated. In 2008-2009, 1384 samples of pig sera were collected from 42 farms in Shandong, Hebei, Heilongjiang, and Jilin provinces and in Tianjin City and were tested for specific antibody against PTV-8 by immunofluorescence assay. All 42 pig herds were positive for antibodies against PTV-8, and 61.3% of the serum samples were PTV-8 positive. During the survey, one PTV strain was isolated and named Fuyu/2009; phylogenetic analysis showed that the PTV Fuyu/2009 belongs to the PTV-8 serotype. The serological results indicate that most if not all pig herds in northeast of China have been exposed to PTV. RT-PCR performed on 114 clinical samples indicated a possible association between PTV and disease. According to genotyping based on partial VP1 sequences, four serotypes (PTV-2, -4, -6, and -8) were identified in northeast of China; sequence data also provided evidence of natural recombination between PTV serotypes and indicated that homologous recombination may be a driving force in PTV evolution. The role of PTV in disease remains inconclusive. The current results together with published results indicate that the prevalence of PTV is increasing among swine herds in northeast of China.