SUMMARY: The susceptibility of inbred strains of mice to infection by phase I , the aetiological agent of Q fever, was investigated by evaluating morbidity, mortality, antibody production and proliferative responses of splenic lymphocytes. Among the 47 strains of mice tested for morbidity and mortality to infection, 33 were resistant, 10 were of intermediate sensitivity, and four were sensitive. A/J mice exhibited the highest mortality, and surviving mice of this strain yielded high concentrations of viable rickettsiae from essentially all organs for more than 3 weeks after inoculation. However, A/J mice developed a protective immune response after vaccination with inactivated cells. Induction of gross pathological responses and antibody production were similar in sensitive mice (strain A/J) and resistant mice (strain C57BL/6J). The LD of phase I for A/J mice was about 1000-fold lower than that for the more resistant C57BL/6J mice. Mice of both strains developed antibody titres against phase I cells, phase II cells, and phase I lipopolysaccharide after the injection of one or more viable phase I organisms of ; five or more rickettsiae caused splenomegaly that was almost proportional to the infecting dose. Suppression of proliferative responses of splenic lymphocytes to concanavalin A, a T-cell mitogen, was apparent after infection of sensitive A/J mice with as few as one to five phase I micro-organisms. However, suppression of proliferation of splenic lymphocytes from resistant C57BL/6J mice required 10 phase I .


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error