A novel pigeon paramyxovirus type 1 isolated from a sick racing pigeon in the Qinghai-Tibet Plateau of China shows high virulence in chickens

Pigeon paramyxovirus type-1 (PPMV-1) is the causative agent of pigeon Newcastle disease (ND), which has caused huge losses to the pigeon industry. In this study, a PPMV-1 strain, PPMV-1/QH-01/CH/23, was isolated from a sick racing pigeon in the Qinghai-Tibet Plateau, China in 2023. The mean death time of chicken embryos and the intracerebral pathogenicity index (ICPI) were 76.8 h and 1.25, indicating a mesogenic strain. Pigeon morbidity and mortality were 100% and 80%, respectively, and both were 80% in chickens; therefore, this isolate was velogenic for both pigeons and chickens. The fusion gene was amplified and sequenced for phylogenetic analysis, and the results indicated that the isolated strain possessed a virulent fusion protein cleavage site motif, ¹¹²R-R-Q-K-R-F¹¹⁷, and belonged to genotype XX (former sub-genotype VIc) of class II; this was different from the predominant sub-genotype, VI.2.1.1.2.2, which is prevalent in pigeons. To the best of our knowledge, this is the first report of a novel genotype XX isolate possessing high virulence for both chickens and pigeons in the Qinghai-Tibet Plateau, China.