A Chlamydia from the peritoneal cavity of mice.

During continuous intraperitoneal passage of liver and spleen suspension in normal stock mice, a syndrome developed which involved ascites and certain other visceral changes but seldom clinical illness and never fatality. From these mice, a chlamydia was established in yolk sacs of chick embryos and in tissue cultures. This agent readily infects mice when inoculated intranasally but is without effect intracerebrally. It has very low pathogenicity for guinea pigs and is resistant to sodium sulfadiazine. These characteristics, together with results of serum neutralization tests, indicate that the agent is different from the Nigg and DeBurgh strains of mouse pneumonitis.