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The complete nucleotide (nt) sequence of eight isolates of beak and feather disease virus (BFDV) obtained from a range of psittacine species with psittacine beak and feather disease (PBFD) from throughout Australia were compared with the sequences of two BFDV isolates previously reported from Australia (BFDV-AUS) and America (BFDV-USA), respectively. All isolates had the same basic structure including the position of the open reading frames, the hairpin structure between ORF1 and ORF2, the nonanucleotide motif (TAGTATTAC) therein, the three motifs of Rep protein encoded from ORF1 and involved in rolling circle replication, and the P-loop motif previously described, but the genome size of the eight isolates ranged from 1992 to 2018 nt. Overall nt identity of the isolates compared to BFDV-AUS ranged from 84 to 97%; the variation was due to a combination of point mutations and a number of deletions and insertions ranging from 1 to 17 nt in size detected in both coding and noncoding regions. The identity of the nt sequence of ORF2 compared to BFDV-AUS varied from 80 to 99%, while the identity of the deduced amino acid sequences varied from 73 to 99%. Phylogenetic analysis grouped the isolates into four clusters but there were no apparent regional differences or differences related to the psittacine species of origin. While seven ORFs with the potential to encode proteins greater than 8.7 kDa were detected in the BFDV-AUS isolate described previously, only three of these ORFs were detected in all 10 BFDV isolates for which sequence data were available. The three ORFs were ORF1 that presumably encodes the Rep protein, ORF2 presumably the major capsid protein, and the ORF previously designated ORF5. The ORF5 was of two size classes in different isolates, 303 and 474 nt, and only the first 303 nt of the viruses with an ORF of 474 nt were common to the other isolates.

Cloning and sequencing of the circular, single-stranded DNA of one isolate of psittacine beak and feather disease virus (BFDV) demonstrate a genome composed of a circular molecule of 1993 nucleotide bases. An analysis of the assembled replicative form demonstrated seven open reading frames (ORFs) (three in the virion strand and four in the complementary strand), potentially encoding seven viral proteins of >8.7 kDa. High amino acid sequence similarity was demonstrated between a potential 33.3-kDa protein product of ORF1 of BFDV and the replicase-associated protein of porcine circovirus (PCV), subterranean clover stunt virus, and faba bean necrotic yellows virus. However, significant similarity in nucleotide or amino acid sequences was not present between BFDV and chicken anaemia virus. A potential stem-loop structure similar to that found in PCV and plant circoviruses was present in the putative encapsidated strand of the BFDV genome. At the top of this structure, a nonanucleotide motif (TAGTATTAC) similar to that of PCV, plant circoviruses, and geminiviruses also was recognised. Comparison of the deduced amino acid sequences of ORF2 of BFDV and PCV demonstrated 29.1% identity, and in both viruses, ORF2 is located on the complementary strand, beginning close to or within the hairpin stem. Our findings provide further evidence of a close relationship among BFDV, PCV, and plant circoviruses but not chicken anaemia virus., (Copyright 1998 Academic Press.)

The pathogenesis and epidemiology of a feather disease in wild Senegal doves (Streptopelia senegalensis) which is morphologically similar to psittacine beak and feather disease (PBFD) was investigated. Although the lesions in doves resembled PBFD there was little evidence for the presence of psittacine circovirus (PsCV). Haemagglutination activity (HA) using type A galah (Eolophus roseicapillus) erythro-cytes was not detected in feathers or livers of affected doves as would occur in PBFD. Low concentrations of HA excreted in the faeces of affected doves was not caused by psittacine circovirus (PsCV) because the antigen in faeces also caused haemagglutination of PsCV-insensitive type B galah erythrocyte and was not inhibited by anti-PsCV antibody. Similar HA of unknown cause was also detected in faeces from clinically normal Senegal doves. Anti-PsCV haemagglutination inhibiting (HI) antibody was not detected in the serum of affected doves or in the blood of 206 clinically normal wild Senegal doves or 17 captive columbid birds in close contact with a flock of psittacine birds that was known to be PsCV-infected. Senegal doves also failed to seroconvert after two inoculations with PsCV purified from the feathers of a PBFD-affected long-billed corella (Cacatua tenuirostris). The results indicate that the feather disease seen in feral Senegal doves in Perth is not due to PsCV although the possibility that it is due to another antigenically distinct circovirus was not eliminated.