Electron-microscopic study of the serological affinity between the antigenic components of phages T4 and DDVI

In an investigation of the antigenic fine structure of phages T4 and DDVI with the use of the neutralization reaction and electron-microscopic observation of the phage-antibody complexes, it has been possible to establish that the head of phage T4 consists of proteins which have antigenic determinants of two types: The first type is identical to the antigens of the head of phage DDVI, and the second type is apparently absent in phage DDVI. The phage DDVI head contains mostly determinants which are common to the phage T4 head, since it was not possible to detect antigenically specific components in the phage DDVI head. The tail sheaths of phage T4 and DDVI appear to be identical in the antigenic respect. A difference has been observed in the fibers and the base plates of the phages investigated. The presence of the following three types of antigens has been established: 1) common to phages T2, T4, and DDVI, 2) common to phages T4 and DDVI, and 3) specific for each phage investigated.