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

Abstract

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<0?0001) between PCR and HA testing of feather samples and PCR-negative birds were 12?7 times more likely to have HI antibody than PCR-positive birds. False-positive HA results with titres up to 1 : 320 were identified in six feather samples that were PCR negative; the haemagglutination detected in these samples was not inhibited by anti-BFDV antisera and was removed by filtration through a 0?22 mm filter. Similarly, one false-negative PCR result was detected in a feather sample that had a high HA titre (>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.

Evidence of Psittacine Beak and Feather Disease Virus Spillover Into Wild Critically Endangered Orange-Bellied Parrots (Neophema Chrysogaster)

“…The discovery of two divergent circovirus genotypes with different host affinities in two sibling Swift Parrot nestlings that had died acutely from PBFD in Tasmania demonstrates the likelihood of infection following shared nest-hollow use by different parrot species (Khalesi et al, 2005). The Swift Parrot is uniquely analogous to the Orange-bellied Parrot in that it is a small endangered migratory psittacine that breeds in nest hollows in Tasmania.…”

“…Blood taken at the nest prior to collection was positive on PCR for BFDV, whereas feathers did not cause hemagglutination (HA) and no response was observed on hemagglutination inhibition (HI) assay of serum. The PBFD diagnostic assays were carried out by the Veterinary Diagnostic Laboratory, Charles Sturt University, following published methods (Ypelaar et al, 1999;Khalesi et al, 2005). These tests have formed the basis for intensive monitoring of wild Orange-bellied Parrots for BFDV since 2000.…”

Phylogenetic analysis of beak and feather disease virus across a host ring-species complex

“…Seroprevalence was assayed using hemagglutination inhibition as described in ref. 45. See SI Materials and Methods for a detailed description of these techniques.…”

Molecular Diagnosis of Beak and Feather Disease in Native Brazilian Psittacines

“…BFDV infection of New World psittacines may result in clinical disease (Phalen, 2006;Piçarra, 2009), reducing their chances of survival in the wild, as previously documented in New Zealand psittacines (New Zealand, 2012). However, efficient immune response may result in a latent subclinical infection, which may become clinically apparent only under stressful conditions (Dahlhausen & Radabaugh, 1997;Khalesi et al, 2005;Phalen, 2006;Piçarra, 2009).…”