Effect of Mycoplasma gallisepticum on genetically defined chickens.

Three parameters were used to measure differences between Arkansas progressor and regressor lines of chickens in response to Mycoplasma gallisepticum inoculations. The responses of regressor and progressor lines to M. gallisepticum did not differ as judged by antibody response, severity of airsacculitis, and resistance of tracheal ring tissue cultures from 20-day-old progressor and regressor chick embryos to M. gallisepticum.