Passive Antibacterial Immunization in Conjunctival Diphtheria in Guinea Pigs.

In a previous paper (Hirose et al., 1962) it was reported that guinea pigs highly immunized against a bacterial suspension of Corynebacterium diphtheriae resisted to a challenge by the conjunctival method (Murata et al., 1959) with a toxinogenic virulent strain without even traces of antitoxic immunity, while a passive transfer of the immunity failed. The reason for this failure may have been due to the fact that the immune serum did not contain enough antibody necessary to protect the conjunctival infection. This may have been plausible, since the antibacterial immunity was not easily established even by active immunization and it was necessary to immunize animals repeatedly over several months. In addition, the heterologous serum used in the former experiments may have been unfavorable for the passive transfer. Therefore, it was tried to use a homologous serum for the passive transfer of the antibacterial immunity. A pooled homologous antibacterial serum was prepared by repeated subcutaneous injections into guinea pigs of a formolized suspension of C 4 strain, an atoxinogenic Corynebacterium diphtheriae. A heterologous serum was produced by immunizing a rabbit by several intravenous injections with the same suspension. Agglutinin titers of the sera against C 4 strain were 1: 1280 for the former and 1: 2560 for the latter. The method of challenge was followed as described before except that the inoculum was