Effect of Antigenic Stimulation on the Specificity of Antibody Produced by Rabbits Immunized with Bacteriophage MS-2 Free

Repeated immunization of rabbits with the RNA coliphage MS-2 resulted in the appearance of an increasing amount of neutralizing antibodies that showed an increased rate of association (i.e., affinity) with the homologous phage antigen. There was a progressive narrowing of the specificity of the antibodies produced after each antigenic stimulation as evidenced by a decrease in the extent of cross-reactions observed with related heterologous RNA phages. These results are discussed in relation to the nature of the antibody response and the antigenic structure of phage MS-2.