Figure 2. Specificity of salivary sIgA against RgpA domains. Recombinant catalytic domain of RgpA (RgpA Cat, lane 1), 44-kDa adhesion hemagglutinin domain (HGRP 44, lane 2), and 15-, 17-, and 27-kDa hemagglutinin domains (HGRP 15–27, lane 3) with histidine tags were separated by SDS-PAGE and transferred to PVDF membrane. Blotted membrane was blocked with phosphate-buffered saline containing 3% bovine serum albumin, reacted with peroxidase-conjugated anti-mouse IgA and developed. Blotted lanes 1, 2, and 3 were probed with saliva from mice immunized nasally with rgpA-HVJ envelope vector.