Paired Chicken and Mammalian Erythrocyte Indicator Systems for Haemagglutination Test and Diagnosis of Newcastle Disease
AbstractThree levels of erythrocytes suspensions, 1.5%, 1% and 0.5% respectively from goat and guinea pig, were compared to conventional 0.5% chicken erythrocytes, in an attempt to investigate the suitability for the two sources of mammalian erythrocytes as indicators for Newcastle disease virus haemagglutination (HA) tests. The results showed that the guinea pig erythrocytes, were associated with the same HA titre (8 log 2); with HA times being 30, 50 and 35 minutes respectively and elusion times were 120, 85 and 105 minutes respectively. The data therefore established biometric and qualitative similarities between the control and these two test dilutions of erythrocytes. In HI tests on sera from commercial poultry, the guinea pig indicator was consistently associated with 2 to 5 fold higher HI titres than the other indicators in some of the flocks tested. A retrospective flock health analysis revealed that the higher titres were associated with confirmable Newcastle Disease (ND) outbreaks in the affected flocks. These findings therefore suggested that the use of standardised guinea pig erythrocytes in parallel with chicken erythrocytes as indicators, might facilitate field ND diagnosis and thus obviate the problem posed by the delay in the requirement for paired sera from acute and convalescent phases of outbreaks in vaccinated flocks, as in existing procedure. The generally recognised simplicity and economy of HI serology would continue to favour its application in preference to other laborious and complicated virologic techniques, especially in medium scale laboratories, as well as in rural developmental and epidemiologic studies.
Key Words: Mammalian erythrocytes, haemagglutination tests, diagnosis, Newcastle disease.
Trop. Vet. Vol.22: (1) 26-32 (2004)