Exploratory Study on Th1 Epitope-Induced Protective Immunity against Coxiella burnetii Infection

Abstract

Coxiella burnetii is a Gram-negative bacterium that causes Q fever in humans. In the present study, 131 candidate peptides were selected from the major immunodominant proteins (MIPs) of C. burnetii due to their high-affinity binding capacity for the MHC class II molecule H2 I-Ab based on bioinformatic analyses. Twenty-two of the candidate peptides with distinct MIP epitopes were well recognized by the IFN-γ recall responses of CD4+ T cells from mice immunized with parental proteins in an ELISPOT assay. In addition, 7 of the 22 peptides could efficiently induce CD4+ T cells from mice immunized with C. burnetii to rapidly proliferate and significantly increase IFN-γ production. Significantly higher levels of IL-2, IL-12p70, IFN-γ, and TNF-α were also detected in serum from mice immunized with a pool of the 7 peptides. Immunization with the pool of 7 peptides, but not the individual peptides, conferred a significant protection against C. burnetii infection in mice, suggesting that these Th1 peptides could work together to efficiently activate CD4+ T cells to produce the Th1-type immune response against C. burnetii infection. These observations could contribute to the rational design of molecular vaccines for Q fever.

From Q Fever to Coxiella burnetii Infection: a Paradigm Change

“…Indeed, it has been shown that virulent C. burnetii induces a Th1 protective immune response, in contrast to avirulent variants (267). Some epitopes of C. burnetii, identified by bioinformatics, are able to stimulate Th1 T cells (268). There is converging evidence that IFN-␥ makes macrophages resistant to C. burnetii.…”

Rapid and Visual Detection ofCoxiella burnetiiUsing Recombinase Polymerase Amplification Combined with Lateral Flow Strips

“…The recombinant plasmid was diluted into a series of concentrations from 1 × 10 4 copies/ μ L to 1 copy/ μ L with Elution buffer (TaKaRa MiniBEST Plasmid Purification Kit Ver.4.0) and added to the optimized RPA reaction system as templates to evaluate the detection limit of the method for detection of positive plasmid. The genomic DNA of C. burnetii was diluted into a series of dilutions with human blood DNA solution and the DNA copies were evaluated using RT-qPCR as described previously [ 5 , 22 ]. Primers and probe sequences used in RT-qPCR were indicated in Table 1 .…”

“…Its broad host range includes domestic and wild animals as well as humans [ 2 , 3 ]. Acute Q fever is usually transmitted to humans by inhalation of aerosols generated by infected animals and may progress to chronic disease complicated by endocarditis, chronic hepatitis, and/or osteomyelitis [ 4 , 5 ], which are sometimes incurable [ 6 , 7 ].…”

Development of a rapid and visual nucleotide detection method for a Chinese epidemic strain of Orientia tsutsugamushi based on recombinase polymerase amplification assay and lateral flow test

“…Genomic DNA was extracted from O. tsutsugamushi, S. aureus, and S. suis using the QIAamp Blood and Tissue Mini DNA kit (Qiagen, Valencia, CA, USA). For quality control, genomic DNA from R. rickettsii, C. burnetii, R. heilongjiangensis, R. sibirica, S. aureus, and S. suis was detected using RT-qPCR, as described previously (Gong et al, 2015;Niu et al, 2008;Qi et al, 2013;Xiong et al, 2017;Xiong et al, 2014;Yu-Xin et al, 2010;Zhu et al, 2012), to be 10 5 copies/ml to 10 8 copies/ml.…”