Antigenic determinants of adenovirus capsids. I. Measurement of antibody cross-reactivity

Evidence is presented that the type-specific antibody to the adenovirus hexon is not simply the antibody with the highest activity for cross-reactive determinants, but is a distinct, minority population that recognizes seperate determinants. To quantify it, we have developed an inhibition method with radio-immunoprecipitation (RIP) as a sensitive assay for the type-specific antibody that remains after all the excess of cross-reactive antibody has been blocked by heterologous antigen. During the primary response, 0.1 to 1% of antibody to types 2 or 5 hexon is type-specific, but after boosting, this population may reach 10 to 20%. Antibody to fiber is more than 70% type-specific during primary and secondary responses. The cross-reacting antibody can be removed on immunoabsorbent columns without affecting the virus neutralization titer of the serum.