Intracerebral infection of mice with ovine strains of Chlamydia psittaci: an animal screening test for the assay of vaccines.
Intracerebral inoculation of mice with the A22 strain of ovine C. psittaci gave a reproducible non-lethal infection; multiplication of the inoculum could be quantitated by titration of mouse brain extracts in tissue culture. Mice which had recovered from infection, or which had been inoculated subcutaneously with living organisms of A22 strain, showed solid resistance to intracerebral challenge infection. However, subcutaneous inoculation of formalin-inactivated chlamydia showed little protective effect unless given in very high dosage. Inactivated vaccines of the heterologous ZC113 strain gave better, but still incomplete, protection against A22 challenge infection than did the homologous inactivated vaccine. The implication of these findings is discussed. The mouse intracerebral protection test appears to be a suitable laboratory procedure for assessing the potency of vaccines against enzootic ewe abortion and for comparing the immunological cross-protection between the various strains of C. psittaci currently found in the natural disease in sheep.
D000818:Animals; D001428:Bacterial Vaccines / Q000276:immunology; D001927:Brain Diseases / Q000276:immunology / Q000382:microbiology / Q000628:therapy*; D002691:Chlamydophila psittaci / Q000276:immunology / Q000302:isolation & purification; D004353:Drug Evaluation, Preclinical; D007109:Immunity; D007167:Immunotherapy; D051379:Mice; D008815:Mice, Inbred Strains; D009956:Psittacosis / Q000276:immunology / Q000382:microbiology / Q000628:therapy*; D012756:Sheep / Q000382:microbiology*
D001428:Bacterial Vaccines