Global evolution dynamics of genotype VI NDVs and dissection of the biological properties of strains from the prevalent sub-genotypes

Genotype VI is the most diverse group of Newcastle disease viruses (NDVs). In addition to infectious disease in pigeons, the potential threat to chicken flocks and the public health implications associated with genotype VI NDVs also need to be addressed. Herein, comprehensive genetic evolution analysis revealed a global distribution pattern and continuous evolution of genotype VI NDVs worldwide. The biological characteristics of genotype VI NDVs belonging to different sub-genotypes were also evaluated. In particular, the widespread transmission, circulation, and constant evolution of currently prevalent sub-genotype VI.2.1.1.2.2 have led to the alteration of receptor binding preference, an increase in replication capacity, and a resultant increase in virulence in chickens. These findings expand our current understanding of the evolution and pathogenesis of genotype VI NDVs.