Role of antibody in Coxiella burnetii infection.

BALB/c mice infected with Coxiella burnetii phase I developed a state of acquired resistance which could be detected during week 2 postinfection. Immune serum, administered to normal mice 24 h before challenge with C. burnetii, appeared to accelerate the development of resistance. An increased clearance rate could be measured in these serum recipients 1 week postinfection. Simultaneous administration of immune serum and C. burnetii did not affect the normal clearance rate of rickettsiae from the spleens of infected mice during week 1, but enhanced clearance of the organism by 14 days postchallenge. Passive transfer of immune serum 24 h after challenge of normal mice with viable C. burnetii had no effect on rickettsial growth within the spleens of animals treated in this fashion. Treatment of athymic mice with immune serum 24 h before challenge with C. burnetii had no effect on rickettsial multiplication within the spleens of these T-cell-deficient animals.