[Oral immunization against tetanus, using liposome-entrapped tetanus toxoid]

A study was made on oral immunization using a tetanus toxoid. Liposome entrapped tetanus toxoid (LTT) was p.o. administered to cats and serum antibody responses were examined. As a result it was known that the LTT antigen induced antibody production in the serum and that an antitoxin antibody titer higher than 0.1 IU/ml, a prophylactic level against tetanus, was produced. On the contrary to this, no antibody was detected in the group administered a tetanus toxoid alone throughout the test period. Also, when an absorbed tetanus toxoid (ATT) was booster-injected to cats p.o. primed with LTT, high responses of the secondary immunization were obtained. Moreover, in case LTT was p.o. administered as a booster antigen, the antitoxin titer in the serum showed a rapid, steep elevation. From these results it has been clarified that LTT on p.o. administration produces an antibody equivalent to the subcutaneous inoculation of ATT.