Differentiation of adenovirus hexon epitopes with monoclonal antibodies by gel diffusion assays.

Nine monoclonal antibodies (MAbs) directed against crystallized human adenovirus type 1 (Ad h 1) hexon were tested with purified homologous and heterologous hexon preparations by gel diffusion. Six MAbs formed a single line with the homologous hexon in a 2-well pattern, and 3 MAbs formed lines only in biclonal combinations with an appropriate MAb. All of the 6 precipitating MAbs formed a continuous line of complete identity when tested simultaneously against homologous and different heterologous hexons. With Ad h 1 hexon a line of double partial identity (double spur) was formed when some pair combinations of 2 MAbs were placed in 2 juxtaposed wells. Other MAbs in the adjacent wells formed a line of identity. The MAbs could be divided into 2 antibody groups (groups A and B) based on this phenomenon. Members of antibody groups A and B apparently identified 2 sterically distinct epitopes: one of them is presumably the genus-specific epitope of the hexons (group A) and the other(s) should be intertype-specific epitope(s). Thus, the gel diffusion method can be used for selecting pairs of MAbs for their specificity to sterically independent epitopes. Mixtures of 2 MAbs belonging to the different antibody groups formed double lines with Ad h 1 hexons. Members of group A showed some helper effect to the members of group B for their precipitin line formation.