Virus-neutralizing antibody titers against 8 avian adenovirus serotypes in breeder hens in Georgia by a microneutralization procedure.

Serums from 16 chicken-breeder flocks in Georgia were tested for virus-neutralizing antibody to 8 serotypes of avian adenovirus. Titers to all 8 serotypes were demonstrated in 8 of the flocks, titers to 7 in 6, and titers to fewer than 7 in the other 2 flocks. Although titers were high overall to some serotypes (types 2 and 8) and low to others (types 1, 4, and 5), with statistically significant differences between many titers, the data were difficult to interpret because of possible heterotypic responses of chickens infected with avian adeno-viruses. Used for titrations of serum antibody was a microneutralization procedure that is inexpensive. It proved also to provide reproducibility since titers from replicate tests differed by less than 3 twofold dilutions. In addition, there was a strong linear relation between titers obtained with the microneutralization procedure and a conventional plaque-assay titration procedure. The microneutralization procedure was less sensitive than the conventional procedure by a factor of about 5.5, but that was considered a disadvantage only with low-titered serums.