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1.
Infect Immun ; 87(11)2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31427447

RESUMO

Coxiella burnetii is an obligate intracellular Gram-negative bacterium which causes human Q fever. An acidified citrate cysteine medium (ACCM-2) has been developed which mimics the intracellular replicative niche of C. burnetii and allows axenic growth of the bacteria. To determine if C. burnetii cultured in ACCM-2 retains immunogenicity, we compared the protective efficacies of formalin-inactivated C. burnetii Nine Mile phase I (PIV) and phase II (PIIV) vaccines derived from axenic culture 7, 14, and 28 days postvaccination. PIV conferred significant protection against virulent C. burnetii as early as 7 days postvaccination, which suggests that ACCM-2-derived PIV retains immunogenicity and protectivity. We analyzed the cellular immune response in spleens from PIV- and PIIV-vaccinated mice by flow cytometry at 7 and 14 days postvaccination and found significantly more granulocytes in PIV-vaccinated mice than in PIIV-vaccinated mice. Interestingly, we found these infiltrating granulocytes to be SSChigh CD11b+ CD125+ Siglec-F+ (where SSChigh indicates a high side scatter phenotype) eosinophils. There was no change in the number of eosinophils in PIV-vaccinated CD4-deficient mice compared to the level in controls, which suggests that eosinophil accumulation is CD4+ T cell dependent. To evaluate the importance of eosinophils in PIV-mediated protection, we vaccinated and challenged eosinophil-deficient ΔdblGATA mice. ΔdblGATA mice had significantly worse disease than their wild-type counterparts when challenged 7 days postvaccination, while no significant difference was seen at 28 days postvaccination. Nevertheless, ΔdblGATA mice had elevated serum IgM with decreased IgG1 and IgG2a whether mice were challenged at 7 or 28 days postvaccination. These results suggest that eosinophils may play a role in early vaccine protection against C. burnetii and contribute to antibody isotype switching.


Assuntos
Anticorpos Antibacterianos/sangue , Vacinas Bacterianas/imunologia , Coxiella burnetii/imunologia , Eosinófilos/fisiologia , Switching de Imunoglobulina/imunologia , Febre Q/prevenção & controle , Animais , Sistema Livre de Células , Imunidade Celular , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Baço/citologia , Vacinação
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