Detection and sequence analysis of avian polyomavirus and psittacine beak and feather disease virus from psittacine birds in Taiwan

Avian polyomavirus (APV) and psittacine beak and feather disease virus (PBFDV) are the most common viral diseases of psittacine birds. In Taiwan, however, the existence of these viruses in psittacine birds has not been established. Polymerase chain reaction (PCR) methodology was therefore employed to ascertain whether APV and PBFDV genomes were present in isolates from psittacine birds of Taiwan. A total of 165 psittacine birds belonging to 22 genera were examined between 2002 and 2005. Findings revealed an APV-positive rate of 15.2%, a PBFDV-positive rate of 41.2%, and an APV/PBFDV dual infection rate of 10.3%. After cloning and sequencing, sequences of the PCR products were compared with sequences obtained from GenBank. For APV, the nucleotide identity among VP1 and t/T antigen coding regions ranged from 97.5% to 100% and 97.6% to 100%, respectively. For PBFDV, the nucleotide identity of ORF V1 and ORF C1 sequences ranged from 92.2% to 100% and 83.3% to 100%, respectively. The derived amino acid sequence alignment for PBFDV ORF V1 fragments revealed the conservation of two replication motifs and of the nucleotide binding site motif. In PBFDV, six of 42 deduced positions in the ORF C1 amino acid sequence were considered hypervariable. The established phylogenetic trees based on the four genome fragments examined in this study did not allow the assignment of particular APV or PBFDV nucleotide sequences to distinct avian species.