Comparison of poly(A).poly(dT) and poly(I).poly(dC) as immunogens for the induction of antibodies to RNA-DNA hybrids.

A goat immunized with poly(A).poly(dT) produced three distinct antibody populations. The major one was specific for RNA-DNA hybrids and was purified from precipitates made with poly(I).poly(dC). It also reacted with hybrids of mixed base composition made with E. coli RNA polymerase. The other populations were purified with poly(A).poly(U) or poly(dT). Three rabbits also produced mainly hybrid-specific antibody in response to poly(A) . poly(dT). A goat immunized with poly(I).poly(dC) formed antibodies reactive with poly(I) and others reactive with poly(dC) but none specific for hybrid structure. Three rabbits did not respond to poly(I).poly(dC). Measurements of reactions with anti-inosine sera, thermal denaturation and sensitivity to S1 nuclease indicated that poly(I).poly(dC) is a less stable helix than poly(A).poly(dT) or poly(I).poly(C). Poly(A).poly(dT) is the more suitable synthetic immunogen for the production of hybrid-specific antibodies.