Survey for serum neuraminidase, free and erythrocyte surface sialic acid from chickens vaccinated against Newcastle Disease and the unvaccinated chickens reared under semi-intensive management system

Abstract

The study was carried out to determine the levels of neuraminidase, erythrocyte surface and free serum sialic acid concentrations of chickens that were vaccinated against Newcastle Disease (ND) and unvaccinated chickens reared under semi-intensive management system in Zaria metropolis. A total of one hundred chickens, fifty each from vaccinated and unvaccinated flocks, randomly selected from ten backyard poultry farms were used for the study. Neuraminidase activity and concentrations of erythrocyte surface and free serum sialic acids were determined for each chicken, using thiobarbituric acid assay method. The values of Packed Cell Volume (PCV) and antibody titres to Newcastle Disease Virus (NDV) were also determined for each chicken by microhaematocrit and Haemagglutination Inhibition (HI) methods, respectively. The mean neuraminidase activity (4.514±1.70 μmol/min) and free serum sialic acid concentration (0.075±0.03 mg/ml) obtained from the vaccinated chickens were significantly higher (p<0.001) than the corresponding values of 1.870±0.16 μmol/min and 0.031±0.02 mg/ml recorded for the unvaccinated chickens. Similarly, the mean HI antibody titres of log2 5.66±3.56 obtained from the vaccinated chickens was significantly higher (p<0.001) than the values of log2 0.980±0.42 recorded for the unvaccinated chickens. On the other hand, there was no significant difference (p>0.05) between the mean erythrocyte surface sialic acid concentration of 0.045±0.01 mg/ml and 0.040±0.02 mg/ml obtained from vaccinated and unvaccinated chickens, respectively. It was concluded that chickens that were vaccinated against ND had significantly higher levels of neuraminidase activity and free serum sialic acid concentrations than the unvaccinated chickens. Further studies are required to isolate and characterize neuraminidase of field strains of NDV present in the area of study. This could possibly give further insight into the role (s) of this enzyme during vaccination of poultry with NDV vaccines. © Asian Network for Scientific Information, 2007.