Comparison of pseudorabies virus China reference strain with emerging variants reveals independent virus evolution within specific geographic regions

- PRV China reference strain Ea forms small plaque than emerging variant.
- Full-length genome of PRV Ea was generated by PacBio SMRT combined with Illumina.
- PRV China reference strain is genetically closer to emerging variant.
- PRV Ea and variant share similar extracellular virion protein polymorphism.
- PRV Ea and variant produced more UL21 protein than Bartha in cells.

Pseudorabies virus (PRV) China reference strain Ea is genetically closely related to newly emerged variants; however, there is limited information about PRV Ea. Here, we compared PRV Ea with new variant strains by growth kinetics, genome sequencing, and protein expression analysis. Growth analysis showed that strain Ea forms smaller plaques than strain HNX. The full-length genome sequence of Ea revealed that it is clustered in the same subgroup as HNX. Ea and HNX strains exhibited similar extracellular virion protein polymorphisms, whereas strain Bartha expressed less VP26 and more GAPDH. In infected cells, strain Ea expressed high levels of IE180 protein, and Ea and HNX produced higher levels of UL21 protein than strain Bartha. These findings provide evidence that PRV China reference strain Ea is genetically closely related to the newly emerged variant strains, indicating that strain PRV China may have evolved independently leading to the emergence of a variant strain.