A comparison of haemagglutination, haemagglutination inhibition and PCR for the detection of psittacine beak and feather disease virus infection and a comparison of isolates obtained from loriids

Division of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA 6150, Australia Correspondence Shane Raidal raidal{at}murdoch.edu.au Psittacine beak and feather disease (PBFD) is recognized as a threat for endangered psittacine birds in Australia, New Zealand and South Africa. Several diagnostic methods for the detection of beak and feather disease virus (BFDV) infection have been developed but there are few studies comparing the relative merits or sensitivity and specificity of each diagnostic test. In this report, the results of PCR, haemagglutination (HA) and haemagglutination inhibition (HI) testing of diagnostic samples collected from 679 samples from a range of psittacine bird species suspected of being infected with BFDV are summarized and compared. There was a strong agreement (kappa = 0·757; P 1 : 40 960) and four false-positive PCR results were detected in a batch of four feather samples. Of 143 birds that were feather PCR positive, only two had detectable HI antibody, and these birds were also feather HA negative, suggesting that they were developing immunity to recent infection. All birds with HI antibody were negative on feather HA testing. The assays confirmed BFDV infection in two endangered swift parrots ( Lathamus discolor ) and phylogenetic analysis of the sequence data generated from ORF V1 of these isolates provide further evidence of BFDV genotypes clustering in parallel with the Loriidae, Cacatuidae and Psittacidae. The GenBank/EMBL/DDBJ accession numbers for the novel BFDV ORF V1 sequences determined in this study are DQ016388–DQ016396.