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Psittacine beak and feather disease (PBFD) has a broad host range and is widespread in wild and captive psittacine populations in Asia, Africa, the Americas, Europe and Australasia. Beak and feather disease circovirus (BFDV) is the causative agent. BFDV has an ∼2 kb single stranded circular DNA genome encoding just two proteins (Rep and CP). In this study we provide support for demarcation of BFDV strains by phylogenetic analysis of 65 complete genomes from databases and 22 new BFDV sequences isolated from infected psittacines in South Africa. We propose 94 % genome-wide sequence identity as a strain demarcation threshold, with isolates sharing >94 % identity belonging to the same strain, and strain subtypes sharing >98 % identity. Currently, BFDV diversity falls within 14 strains, with five highly divergent isolates from budgerigars probably representing a new species of circovirus with three strains (budgerigar circovirus; BCV-A, -B and -C). The geographical distribution of BFDV and BCV strains is strongly linked to the international trade in exotic birds; strains with more than one host are generally located in the same geographical area. Lastly, we examined BFDV and BCV sequences for evidence of recombination, and determined that recombination had occurred in most BFDV and BCV strains. We established that there were two globally significant recombination hotspots in the viral genome: the first is along the entire intergenic region and the second is in the C-terminal portion of the CP ORF. The implications of our results for the taxonomy and classification of circoviruses are discussed.
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Journal of General Virology vol. 92 , part 4, pp. 752–767.
Supplementary Fig. S1. (a) Pairwise identity plots of beak and feather disease circovirus / budgerigar circovirus (BCV). Supplementary Fig. S2. Distribution of positive and negative selection in the replication protein and coat protein ORFs of beak and feather disease circovirus and budgerigar circovirus determined by fixed effects likelihood methods. Supplementary Fig. S3. Maximum-likelihood phylogenetic tree of the Rep and CP protein sequences of the beak and feather disease circovirus and budgerigar circovirus isolates with strain demarcation. Supplementary Fig. S4. Two-dimensional graphical representation of pairwise (pairwise deletion of gaps) cp and rep nucleotide sequence identity of all beak and feather disease circovirus and budgerigar circovirus genomes.
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