Comparison Of Four Anti-Avian IgY Secondary Antibodies Used In Western Blot And Dot-Blot ELISA To Detect Avian Bornavirus Antibodies In Four Different Bird Species

Escandon, Paulina; Heatley, J Jill; Berghman, Luc R; Tizard, Ian; Musser, Jeffrey MB

In 2008, avian bornavirus (ABV) was discovered to be the causative agent of Parrot bornavirus syndrome (PaBVs), formerly known as macaw wasting disease, proventricular dilatation disease or PDD, enteric ganglioneuritis and encephalitis, and avian ganglioneuritis. [1] [2] [3] Since then, multiple ABV genotypes have been recognized in over 80 different species such as psittaciformes, passeriformes, and waterfowls. 4 Diagnosis of PaBVs includes clinical signs and radiological changes, detection of viral antigen, viral RNA or ABV antibodies, gross pathology, and histopatholgy. [5] [6] [7] [8] Sampling for histopathology and tissue immunoassays, especially of nervous tissues, is not practical in living birds, thus these tests are more commonly used in post-mortem diagnosis. Reverse transcriptase polymerase chain reaction (RT-PCR) can utilize less invasive samples such as feather follicles, feces/urine, and cloacal swabs, 5, 7, [9] [10] [11] [12] [13] however sensitivity will vary due to intermittent viral shedding. [13] [14] [15] Immunologic testing comparing ABV specific antigens found that the viral nucleoprotein is immunodominant and hence the best antigen to use in a microtiter plate ELISA and in fluorescent antibody assays. 9, 16 A mixed anti-avian species IgY secondary antibody is often used in ABV serologic tests. 8, 9, [17] [18] [19] [20] The anti-bird secondary antibody, produced in goats using immunoglobulins from the White-crowned sparrow, Ringed turtle dove, domestic chicken, and Muscovy duck, a has been used in other ELISAs for the detection of arboviruses, flaviviruses, alpha-viruses, and poxviruses. [21] [22] [23] [24] The advantage of an anti-bird secondary antibody is the range of species that can be tested. This anti-bird secondary antibody has been used in serologic tests for the detection of antibodies in psittacine birds, even though the immunogen used to stimulate this secondary antibody did not contain antibodies from psittaciformes. Anti-passerine IgY secondary antibody produces better results than the anti-bird IgY secondary antibody or the anti-chicken IgY secondary antibody for serologic assays on passerine birds. 25 This suggests that species-specific secondary antibodies may provide more sensitive results in immunologic assays than commercially available mixed species anti-bird secondary antibody. In assays that employ short antigen-antibody incubation times, such as dot-blot or lateral flow ELISAs, a species-specific secondary antibody may be more useful when testing psittacine birds. Additionally due to the large variety of avian species susceptible to ABV infection, a low affinity of the secondary antibody could result in erroneous test results. The goal of this study was to evaluate the specificity of different avian secondary antibodies used in Western blot and dot-blot ELISA to detect ABV antibodies in the plasma of Blue and gold macaw (Ara ararauna), Cockatiel (Nymphicus hollandicus), Monk parakeet (Myiopsitta monachus), and Mallard (Anas platyrhynchos).