Electron microscopic investigations of the interaction between the T2-phage and its IgG-and IgM-antibodies.

The morphology of the antigenic T2 bacteriophage, when complexed with its IgG and IgM antibodies, was investigated with the aid of the electron microscope. The surface of T2 contains at least two distinct antigenic substances located at the head membrane and at the tail. Antibodies directed against the antigenic head membrane formed bridges between two adjacent phage heads. IgG antibodies were observed combined by one of their short ends to the head membrane, and tangles of antibody molecules were sometimes noted on the head membrane. A combining site of the IgM antibody linked to a phage head was occasionally detected. Neutralizing antibodies against T2 reacted with the distal portion of the phage tails. A few IgM antibody molecules were found which appeared to plug the tail base plate. Tail fibers of T2 were prepared and injected into rabbits for production of specific, neutralizing antibodies. One percent IgG antifiber antibody had a neutralization rate constant, K, around 290, and 0.2% IgM antifiber antibody had an average K value of 1.9. Those specific, neutralizing antibodies were detected at the tail fibers of neutralized T2 phages.