Serologic Response of Chickens Vaccinated with Inactivated Preparations of Mycoplasma gallisepticum

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Abstract
Several lots of inactivated M. gallisepticum (MG) vaccine were prepared from 1% suspensions of the R strain. Portions were inactivated with 0.1% .beta.-propiolactone at room temperature (24.degree. C) for 3 h and other portions were agitated with 0.5% formalin at 37.degree. C for 3 h. Part of each lot was processed to provide oil-emulsion preparations with various ratios of aqueous phase to oil phase. Tween 80 was added to the aqueous phase of most vaccines and Arlacel 80 was added to the oil phase before final blending. The resulting hemagglutination-inhibition (HI) titers decreased in magnitude and duration in the following order: aqueous phase to oil phase ratios of 1:2, 1:4 and 1:1 followed by 25% Al(OH)3 and aqueous vaccines. There was little difference in HI response of young broiler and egg-laying-type chickens injected by the intra-foot-pad or s.c. routes with 0.5-ml doses of vaccines inactivated by formalin or .beta.-propiolactone. Less than 0.25 ml was inadequate, and more than 0.5 ml was not greatly better. Two doses 8 wk apart produced higher HI titers over a longer period than did a single dose. All of the water-in-oil vaccine emulsions were stable for at least 60 days at 37.degree. C. No visible tissue reactions were produced by any of the vaccines studied.