Identification and characterization of novel genotypes of psittacine beak and feather disease virus from budgerigar in China.

Psittacine beak and feather disease (PBFD) is a common disease in psittacine bird that caused by beak and feather disease virus (BFDV). BFDV is widely spread and threatening psittacine birds worldwide. However, the BFDV infection in China remains largely unknown. In this study, a surveillance study of BFDV was conducted in three budgerigar breeding facilities, which showed that 66.6% of collected faeces samples were positive for BFDV. Full genomes of nine BFDV circulating in the three budgerigar breeding facilities (three for each facility) were determined and analysed. The full genomes shared 75.9% to 87.5% identity with the known genotype BFDV. Phylogenetic analysis of the full genome indicated that the BFDV circulating in China formed a separated group, and the nine isolates fell into three subgroups, suggesting that different unique BFDV genotypes are circulating in China. Notably, the Cap genes of three strains (SD3, SD5 and SD9) showed low identity (67.9% to 70%) to all the known genotypes of BFDV. Phylogenetic analysis showed that these three Cap genes formed a unique lineage that is different from all known genotypes, which suggested that the SD3, SD5 and SD9 strains identified in this study belong to a novel genotype that has not been reported. However, the origin of this genotype remains unclear. All the data indicated that the different unique genotypes of BFDV are co-circulating in China, and active surveillance of BFDV is warranted.