Blocking of immunofluorescence in the titration of membrane and intracellular reactive antibodies associated with herpesvirus of turkeys.

Blocking of the direct immunofluorescence (IF) reaction allowed titration of anti-membrane antigen (MA) or anti-intracellular antigen (IA) antibodies induced by herpesvirus of turkeys (HVT). The titers (blocking index) obtained by the blocking IF test were well correlated with those determined by the IF test. The results suggest that the blocking IF test was a simpler and better method for titration of a large number of serum samples from chickens infected with HVT.