[Use of a concentrated and purified vaccine against chlamydial abortion in sheep].

Attempts were made to immunize sheep against chlamydial abortion with a purified, concentrated, and absorbed vaccine. The latter proved innocuous and unreactive, and was applied at rates of 0.5 to 1.00 cm3. It was found that at a single vaccination of the sheep with 0.5 cm3 as many as 91.42 per cent responded with the production of antichlamydial complement-fixing antibodies on the 45th day of 1:8 to 1:512 titers; 96.43 per cent of the animals responded on the 111th day, the titers ranging from 1:8 to 1:256. At twofold vaccination on the 1st and the 45th day with 0.5 and 1.00 cm3 vaccine, respectively, 100% of the sheep showed antibodies on the 111th day, the titers being within the 1:16 to 1:256 range 49.69 per cent showed antibodies on the 260th day within the 1:4 to 1:512 range. No abortions, stillbirths, and birth of underdeveloped lambs were seen.