Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, USA.
Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, USA
Infect Immun. 2019 Oct 18;87(11). doi: 10.1128/IAI.00376-19. Print 2019 Nov.
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 and allows axenic growth of the bacteria. To determine if cultured in ACCM-2 retains immunogenicity, we compared the protective efficacies of formalin-inactivated 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 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 SSC CD11b CD125 Siglec-F (where SSC 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 and contribute to antibody isotype switching.
是一种专性细胞内革兰氏阴性菌，可引起人类 Q 热。已开发出一种酸化柠檬酸盐半胱氨酸培养基（ACCM-2），该培养基模拟了的细胞内复制生态位，并允许细菌的纯培养生长。为了确定在 ACCM-2 中培养的是否保留免疫原性，我们比较了福尔马林灭活的 9 英里 1 期（PIV）和 2 期（PIIV）疫苗在接种后 7、14 和 28 天的保护性功效，这些疫苗分别来自纯培养。PIV 在接种后 7 天即可提供针对强毒的显著保护，这表明 ACCM-2 衍生的 PIV 保留了免疫原性和保护力。我们通过流式细胞术在接种后 7 和 14 天分析了 PIV 和 PIIV 疫苗接种小鼠脾脏中的细胞免疫反应，发现 PIV 疫苗接种小鼠中的粒细胞明显多于 PIIV 疫苗接种小鼠。有趣的是，我们发现这些浸润的粒细胞是 SSC CD11b CD125 Siglec-F（其中 SSC 表示高侧散射表型）嗜酸性粒细胞。与对照相比，在 PIV 疫苗接种的 CD4 缺陷型小鼠中，嗜酸性粒细胞的数量没有变化，这表明嗜酸性粒细胞的积累依赖于 CD4 T 细胞。为了评估嗜酸性粒细胞在 PIV 介导的保护中的重要性，我们接种并挑战了嗜酸性粒细胞缺陷型 ΔdblGATA 小鼠。与野生型相比，ΔdblGATA 小鼠在接种后 7 天接受挑战时疾病明显更严重，而在接种后 28 天接受挑战时则没有明显差异。然而，无论在 7 天还是 28 天接种后接受挑战，ΔdblGATA 小鼠的血清 IgM 升高，IgG1 和 IgG2a 降低。这些结果表明，嗜酸性粒细胞可能在早期疫苗对的保护中发挥作用，并有助于抗体同种型转换。
