| Abstract: | Specific antibodies were investigated in serums of chicks vaccinated with live vaccine and revaccinated with inactivated vaccine against the infectious bursal disease virus, using three methods. An ELISA technique was used to determine antibody titres at a fourfold serum dilution; the reaction was evaluated visually. The results were compared with the titres of neutralizing antibodies and percentage of samples with precipitin activity (Fig. 1). The average values of neutralizing antibody titres and ELISA titres were found to have an analogical pattern; a decrease in maternal antibodies on the first days of chick life and an increase in the antibodies after vaccination, accompanied by an increase in precipitin activity, were typical in these tests. Using the different ELISA technique, 138 samples of fowl serum were examined (Fig. 2). The high correlation, r = 0.85, was found between the ELISA titres determined by visual reading of the reaction within the fourfold serum dilutions and the absorbance values determined at single serum dilution. Applying a spectrophotometer programme, a scale of antibody quantification was made up pursuant to the intensity of immunoenzymatic reaction. For the purposes of method reproducibility, the evaluation was made within the average values of absorbance of positive serum on the one hand and of negative serum on the other. The span of these values was divided into ten equal parts, designated by degrees 0 to 9. Corresponding degrees of positivity were assigned to the examined samples in dependence on the determined value of absorbance (Fig. 3). The correlation r = 0.61 was found between the ELISA values and the titres of neutralizing antibodies.(ABSTRACT TRUNCATED AT 250 WORDS) |
