Sequence comparison of pigeon circoviruses.

Circovirus infection is responsible for economic losses in all categories of pigeons, especially in meat pigeons, because of its immunosuppressive character . Diagnosis of PiCV infections was originally dependent on histology or electron microscopy. In the absence of a cell culture virus propagation system and virus-specific antibodies for detecting virus antigen, additional diagnosticapproaches have focussed on methods that detect PiCV DNA. The application of molecular tests in feces, in swabs or eggs, is of basic importance since it makes possible to identify virus carriers, that can be removed from the loft. In this paper the genome sequences of eight pigeon circoviruses (PiCV) were determined and compared with four previously published sequences. The viruses compared were from the USA, five European countries , China and Australia and included PiCVs from racing, feral, ornamental and meat pigeons and a Senegal dove (Streptopelia senegalensis). The 12 PiCV genomes, ranging from 2032 to 2040 nucleotides in length, displayed similar organizations. Pairwise comparisons showed that the genome nucleotide sequence identities ranged from 85.1% to 97.8% and that the amino acid identities of the putative replication associated (Rep) and putative capsid (Cap) proteins displayed ranges of 91.5-99.1% and 73.0-99.3%, respectively. Comparative analyses identified conserved nucleotide sequences within the Rep gene and 3' intergenic regions, which would be suitable for diagnostic PCR primers, and variable amino acid sequences within the capsid proteins, which should be considered when selecting virus isolates for vaccine development. .