A. Specific response, following background subtraction, to a subset of recombinant vaccinia antigens on the micro-ELISA array using sera from a vaccinated individual (1/300). B. Following Cibacron Blue (F3GA)-agarose treatment of the sera to remove albumin, specific responses with background subtracted are also reduced indicating partial removal of the IgG component. C. Following pretreatment of the sera with Protein A-agarose removing the IgG component, all specific anti-vaccinia protein reactivity is removed. D. For this individual, the background independent of any antigen presence was high; removal of albumin reduced the background by almost 0.5, but reduced the IgG signal by a similar amount (see panel B). Removal of the IgG component alone eliminated the background entirely.