A micro-scale serum neutralisation test for the detection and titration of antibodies to chicken anaemia agent--prevalence of antibodies in Danish chickens.
A micro-scale screening neutralisation test (SNT) and a method for end point titration of sera for antibodies to chicken anaemia agent (CAA) were developed. All 25 known positive sera gave positive results by the SNT, while 24 of 25 sera, supposed to be negative according to an alternative neutralisation test method, gave negative results by the SNT. The remaining one sample was repeatedly positive by the SNT and by endpoint titration. A total of 1161 chicken serum samples from 97 flocks, representing the different categories of the commercial chicken population in all regions of Denmark, were tested for the presence of neutralising antibodies against CAA. Of these 861 (74%) samples representing 87 (90%) flocks gave positive results. Generally the proportions of positive samples per flock and positive flocks increased with increasing age of birds. Neutralising titres ranged from 3.1 to 5.8 log(10) per ml. Again values tended to increase with increasing age, though maternal levels in 1-day-old chicks were usually high.
Jørgensen
P H
PH
Institute of Avian Diseases, Langaa, Denmark.