Table 3 Proteomic approaches for C. burnetii biomarker selection

Detection of specific markers for Cb isolates

MALDI-TOF MS

Cb: RSA493, BUD, Priscilla (CYSEE)

-

Optimization of method for typing Cb for specific strains or clinical isolates

RSA493-specific: CBU_1637, CBU_0401, CBU_0394, CBU_1592, CBU_1378, CBU_0403, CBU_0078, CBU_0961, CBU_1698, CBU_0644, CBU_1055 Priscilla-specific: CBU_0149, CBU_0438, CBU_0168, CBU_0745 BUD-specific: CBU_1989, CBU_2085

[20, 54]

Identification of Cb strains and isolates

MALDI-TOF MS

Cb: NMI, Australian QD, M44, KAV, PAV, Henzerling, Ohio (CYSEE)

-

Cb isolate typing or diagnosis

Mass spectral peaks (1000-6000 Da), species-selective and strain-specific

[55]

Proteome of Cb NM I

2-DE and nanoLC-ESI MS/MS, LC-MALDI TOF/TOF MS, MALDI-TOF MS

TPE Cb RSA493, NM I (CC)

-

Markers of early stage infection, and therapeutic or vaccine development

197 distinct proteins. Vir and Strep: CBU_0691, CBU_0683 SP: CBU_0091, CBU_0109, CBU_0395, CBU_0867, CBU_1221, CBU_1268, CBU_1718, CBU_1910

[19]

In silico prediction of OMPs and identification of Cb (NM I) LP

Bioinformatics

Cb RSA493 genome sequence

-

Vaccine development or serodiagnosis

21 predicted OMPs and 9 LP; LP: CBU_1190 (LolA), CBU_1829 (LolB)

[59]

Proteome of Cb strain NM phase II

2-DE, 2D SDS-tricine PAGE, MALDI-TOF

TPE Cb NM II (CC, Vero)

-

Markers of active Cb infection, serology or therapeutic development

Proteins involved in Cb pathogenesis and survival mechanisms (NM II)

[94]

Proteome of Cb I and II

LC-MS/MS

Cb NM I and II (CYSEE)

-

Phase I and phase II distinct biomarkers, serology or biotyping (blood transfusion)

150 proteins reported (pI > 9. 5); virulence type I and T4SS: CBU_0884, CBU_0085, CBU_0318, CBU_0744, CBU_1099, CBU_1352, CBU_0338, DotD protein (CBU_1643); Anks: CBU_0898, CBU_1482; 7 enzymes involved in LPS phase I synthesis: CBU_0676, CBU_0678, CBU_0674, CBU_0681, CBU_0682, CBU_0683, CBU_0691, CBU_0846, CBU_1657

[17]

Cb secretome

Tricine-SDS PAGE, ESI-MS/MS, bioinformatics

Cb NM II (CC, Vero)

Cytoplasmic fraction from infected Vero cells

Characterization of T4SS, drug development

50 T4SS effector candidates: CBU_1440, CBU_0312, CBU_1091, CBU_1386, CBU_1518, Orf145, QpH1_p21, CBU_1297, CburD_01001397

[33]

Two Cb strains, subproteome (OMPs) and candidate proteins for serodiagnosis

Tris-Tricine SDS-PAGE, doubled SDS-PAGE, IP 2-DE, MALDI TOF/TOF

Cb strains NM RSA 493 II (acute) and CbuG_Q212 II (chronic), (CC, Vero)

OMP-enriched fraction, 1 HS (chronic)

Subproteome of Cb, chronic Q fever markers

86 identified OMPs. SP: htpB, CBU_0236, CBU_0263, CBU_1471, CBU_0572, CBU_0235, CBU_1916, CBU_0612, CBU_0937

[56]

Immunoproteomics or serology

Candidate proteins for acute Q fever serodiagnosis

IP/serodiagnosis

17 Cb strains (CC) (BGM or L929)

RP ada (rada), AS immunized with rada

Marker of acute Q fever

adaA (CBU_0952)

[31, 63]

Identification of Cb cell-variant-specific common SCV/LCV proteins

IP (2-DE, MALDI-TOF)

Purified SCVs and LCVs

HS (convalescent-phase, acute Q fever), AS from infected or vaccinated guinea pigs

Subunit vaccines or serodiagnostics for acute Q fever, unique SCV/LCV markers

Proteins that are differentially expressed in SCV and LCV forms. SP: CBU_1718, CBU_0236, CBU_0229, CBU_1943, CBU_1416, CBU_0952, CBU_0963, CBU_0737, CBU_0497, CBU_1200

[31]

SP for serodiagnosis of Q fever endocarditis

IP (2-DE/MALDI-TOF)

TPE Cb NM II (CC, Vero)

HS (acute Q fever or IE Q fever)

Markers of chronic Q fever (IE), serodiagnosis

CBU_0612, CBU_0480

[57]

Identification of Cb proteins reacting with Cb mAbs

IP (2-DE/MALDI-TOF) RP-based ELISA

TPE Cb NM II (CC, Vero)

Specific mAbs; HS acute or chronic (IE)

Markers of chronic Q fever (IE), serodiagnosis

Q fever markers (general): CBU_1910, CBU_0236 Chronic Q fever marker (IE): CBU_0937

[58]

SP for early serodiagnosis of Q fever

IP (2-DE, LC-MS/MS) (pH 5-8, pH 3-10; phase I and phase II antigens )

TPE Cb NM I and II (CC, L929), Cb NM RSA493 I (CYSEE)

AS from immunized guinea pigs

Markers of early stage acute Q fever, serodiagnosis or vaccine development

Phase-I-specific SP: CBU_1706, CBU_12190, CBU_0495, CBU_0780, CBU_0955, Phase-II-specific SP: CBU_1290, CBU_0235, CBU_0215, CBU_0572, CBU_1398, CBU_0236, CBU_0092, CBU_1241, CBU_1396, CBU_1227, CBU_0481, CBU_0299, CBU_0481, CBU_0495, CBU_0482, CBU_0937, CBU_0236

[68]

RP-based approaches

Candidate RPs for Q fever vaccine development and serodiagnosis

TAP products and expression of selected SP

HS (acute, chronic phase vaccine)

Serodiagnosis or vaccine development

SP: CBU_0008, CBU_0381, CBU_0612, CBU_0781, CBU_1115, CBU_1143, CBU_1157, CBU_1249, CBU_1853, CBU_1869 Top candidates: CBU_0781 (AnkG), CBU_1115 (lipoprotein), CBU_1143 (YajC)

[66]

Candidate RPs for Q fever vaccine development and serodiagnosis

Protein microarray

HS Q fever (general)

Markers of Q fever (general)

SP: CBU_1910, CBU_0891, CBU_0109, CBU_1143, CBU_0612, CBU_0092, CBU_0545, CBU_1398, CBU_0630, CBU_1513, CBU_1719, CBU_0229, CBU_0653

[69]

Candidate RPs for Q fever vaccine development and serodiagnosis

ELISA (HS), ELISPOT (AS)

11 RPs, Cb NM RSA493 I

HS Q-fever (IFA-positive, convalescent), HS chronic (transgenic mice, immunized with Cb NM RSA493 I)

Subunit vaccine development, serodiagnosis

SP: CBU_1910, CBU_1716, CBU_612, CBU_718, CBU_311

[67]

Identification of Cb SP

IP (2D, LC-MS), tripartite fusion RP

TPE Cb (I and II Henzerling strain) (CC, Vero)

HS Q fever (general)

Serodiagnosis or vaccine development

SP: CBU_0091, CBU_0109, CBU_0395, CBU_0867, CBU_1221, CBU_1268, CBU_1718, CBU_1910 Six RP(Cb II): GroEL, Com1, RecA, EF-Tu, OmpA-like and FtsZ

[65]