The Haemagglutination Spectrum of Psittacine Beak and Feather Disease Virus in Brazilian Psittacine Birds
Paula Soares, Marta B.Guimaraes, and Edison L.Durigon
Department of Microbiology, Institute of Biomedical Science, University of São Paulo, São Paulo (Brazil)
Key words: Avian, Psittacine, Haemagglutination spectrum, Psittacine Beak and Feather Disease virus, PBFD virus, Circovirus
Abstract. Erythrocytes of Blue and Gold Macaws (Ara ararauna), Red-shouldered Macaws (Ara nobilis), Blue-fronted Amazon Parrots (Amazona aestiva), and Orange-winged Amazon Parrots (Amazona amazonica) were tested for agglutination in the presence of psittacine beak and feather disease (PBFD) virus. The haemagglutination assay technique used a 1% erythrocyte suspension in phosphate-buffered saline (PBS, pH 7.2). The virus was aliquoted at a 1:1000 dilution. The viral suspension was applied in two-fold dilutions up to 1/32, and the plates were incubated at 37oC for 45 minutes . Agglutination activity was not detected in any of the 23 specimens that were tested.
Introduction
Psittacine beak and feather disease virus (PBFDV) is a non-enveloped single stranded DNA virus of the Circoviridae family associated with feather dystrophy and loss in clinically affected birds. 2,4-9 Circoviruses are named from their unique circular DNA genomes. 1,10,11 PBFDV has been shown to haemagglutinate erythrocytes from the Goffin's Cockatoo (Cacatua goffini), Galah (Eolophus roseicapillus), guinea pig, some geese (Anser anser), Eastern Slender-billed Corella (Cacatua tenuirostris), some Sulphur-crested Cockatoos (Cacatua galerita), Gang Gang Cockatoo (Callocephalon fimbriatum), and Major Mitchell’s Cockatoo (Cacatua leadbeateri). 6-9 The present study describes the agglutination activity of PBFDV with erythrocytes from four different Brazilian species of psittacine birds.
Materials and Methods
Erythrocyte preparations: Blood samples for HA assay were taken from four different psittacine species by radioulnar venipuncture and stored in a equal volume of Alserver’s solution at 4°C for up to 10 days, following the procedure of Raidal and Cross. 8 Any haemolysed blood was discarded. Prior to use, erythrocytes were washed three times in PBS and then diluted to a concentration of 1%. Blood was collected from 2 Red-shouldered Macaws (Ara nobilis), 2 Orange-winged Amazon Parrots (Amazona amazonica), 8 Blue and Gold Macaws (Ara ararauna), and 11 Blue-fronted Amazon Parrots (Amazona aestiva).
Haemagglutination assays: The HA tests were performed as described by Raidal, et al and Mochizuki and coworkers. 3,6 The antigen was used at a 1:1000 dilution and was stored at -70oC until use. Haemagglutination was tested at pH 5.0 to 8.0 in PBS. Thirty mL of PBS was deposited in each well. Next, 30 mL of PBFDV (aliquoted at 1:1000) was deposited in the first line of the plate. Subsequently, two-fold dilutions were made to a final dilution of 1/32. The 1% erythrocyte suspensions were then added to each well and the plate was incubated at 37oC for 45 minutes. Following incubation, agglutination activity was evaluated by visual inspection.
Results
Haemagglutination spectrum: Erythrocytes from the four 4 species of psittacine birds that were tested exhibited no agglutination activity in the presence of the PBFDV. These data are presented in Table 1.
| Table 1. Haemagglutination spectrum of PBFDV in four species of Brazilian psittacine birds |
| Psittacine species |
Number of specimens |
Spontaneous agglutination
of erythrocytes |
Agglutination activity
in presence of PBFDV |
| Amazona aestiva |
11 |
not present |
not present |
| Amazona amazonica |
2 |
not present |
not present |
| Ara ararauna |
8 |
not present |
not present |
| Ara nobilis |
2 |
not present |
not present |
Discussion
The results of this study show that erythrocytes from these Brazilian psittacine birds did not demonstrate agglutination activity in the presence of the PBFDV. However, because we know that hemagglutination activity may vary among individuals, we cannot say that these species as a whole are not erythrocyte-sensitive to PBFDV. Further insight into hemagglutination activity will be gained by testing erythrocytes from more individuals and different species of Brazilian psittacine birds. Such studies will help to confirm or refute the haemagglutination spectrum of PBFDV in various species of Brazilian birds.
Acknowledgments
We would like to thank Drs. Ken Latimer and Branson Ritchie from the College of Veterinary Medicine, University of Georgia, for providing the circovirus for HA testing; the board of directors and veterinarian Liliane of "Parque Ecológico do Tietê" for the psittacine birds; and also FAPESP (Fundação de Apoio à Pesquisa do Estado de São Paulo) for financial support.
References
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