Psittacosis Vaccines Prepared from Chick Embryo Tissues

[摘要] 1. 1. Psittacosis (strain 6 BC) vaccines have been prepared which, following 3 intraäbdominal injections of 0.5 ml each, protected 75 percent or more mice against intraäbdominal challenges of 10,000 to 1,000,000 LD50 of the virus, and conferred definite protection against small challenges (1 to 10 MLD) by the respiratory and intracerebral routes.2. 2. The best vaccines were prepared from infected yolk-sacs by a procedure which involved lyophilization prior to ether extraction. Such vaccines were extremely rich in elementary bodies.3. 3. The immunizing potency of vaccines appeared to be related to their elementary body content.4. 4. The complement-fixing antigenic titer of vaccines appeared to have no relation to immunizing potency.

[学科分类] 生物科学（综合）