INDUCTION OF PROVENTRICULAR DILATATION DISEASE BY GANGLIOSIDE INOCULATION IN HEALTHY COCKATIELS (NYMPHICUS HOLLANDICUS)

Proventricular dilatation disease (PDD) has been identified in parrots since the 1970s but only recently have Parrot bornaviruses (PaBV) been correlated with this condition.1,2,3 This association has not been sufficient to elucidate the pathogenesis of this disease process as not all birds infected with PaBV develop PDD. Conversely, not all birds affected with PDD test positive for PaBV. An autoimmune mechanism (production of autoreactive antiganglioside antibodies), similar to the Guillain-Barrè Syndrome in humans, was proposed in the pathogenesis of PDD1,6. To demonstrate the role of gangliosides in this pathology, a preliminary study was conducted. A group of five, 9 month old PaBV free Cockatiels (Nymphicus hollandicus) were inoculated with parrot derived gangliosides. Gangliosides were extracted from the brains of an Umbrella cockatoo (Cacatua alba) and an African gray parrot (Psittacus erithacus) with chloroform-methanol–distilled water according to the method of Vorwerk7. Both donor birds and the pooled ganglioside extract tested negative for PaBV. Four cockatiels were injected with 0.1 ml of ganglioside extract in the pectoral musculature once every 30 days for 3 treatments. One control cockatiel was injected with 0.1 ml of physiological saline only. All inoculated birds demonstrated a 10-25% body weight loss ninety days following the last inoculation whereas the control bird exhibited a 20% weight gain. One inoculated cockatiel died of “classic” PDD 5 months after the last inoculation. This preliminary study highlights the possibility of developing PDD without the presence of PaBV in healthy parrots and the role of gangliosides in the pathogenesis of the disease.