Neutralizing capacity of the induced antisera. Neutralization of KoRV by rat sera after immunization with recombinant rgp70/p52 protein (A), recombinant zp15E protein (B) and both proteins together (C). The titers of neutralizing antibodies in the sera from goats immunized with rgp70/p52, and rp15E are shown in (D). A serum obtained by immunization with the recombinant rp27Gag (which is not neutralizing) was included for comparison. The dashed line indicates 50% neutralization.