Table 2.
Overview on experimentally identified rickettsial immunogens, their localization, and recognition by B and/or T cells. The table provides an overview of so-far-known antigens from rickettsiae and orientia, their localization and function, and whether they are recognized by B and/or T cells. OM: outer membrane, IM: inner membrane, C: cytoplasm, P: periplasm, EC: extracellular, √: experimentally proven recognition. Empty fields: not described.
| Rickettsial | Localization | Function | Recognition by | ||
|---|---|---|---|---|---|
| Immunogens | B | CD4+ | CD8+ | ||
| Sca0 (OmpA) | OM | adhesion and invasion | √ | √ | |
| Sca1 | OM | adhesion and invasion | √ | ||
| Sca2 | OM | adhesion and invasion | √ | ||
| Sca3 | OM | adhesion and invasion | √ | ||
| Sca4 | C | binds and activates vinculin [107] | √ | ||
| Sca5 (OmpB) | OM | adhesion and invasion | √ | √ | √ |
| Adr1 | OM | adhesion and invasion, binds vitronectin, confers resistance to complement-mediated killing [108,109] | √ | ||
| Adr2 | OM | adhesion and invasion, binds vitronectin, confers resistance to complement-mediated killing [110] | √ | √ | √ |
| TolC | OM | adhesion and invasion of vascular endothelial cells [111] | √ | ||
| OmpW | OM | adhesion and invasion of vascular endothelial cells [111] | |||
| Porin-4 | IM/OM/EC | export of glycostructures (eg. LPS O-antigen) | √ | ||
| YbgF | OM/C | tol-pal system protein | √ | √ | √ |
| GroEL | C/OM } | 60 kDa heat shock protein, molecular chaperone; surface-exposed [105,106,112] |
√ | ||
| PrsA | OM/C | Parvulin-like peptidyl-prolyl cis-trans isomerase (Parvulin-like PPIase), protein export protein | √ | ||
| RplY | C/OM | 50S ribosomal protein L25/general stress protein Ctc | √ | ||
| RpsB | C/OM | 30S ribosomal protein S2 | √ | ||
| SurA | C/OM | chaperone SurA, parvulin-like peptidyl-prolyl isomerase | √ | ||
| RP403 | C/OM | RecB family exonuclease | √ | ||
| RP598 | C/OM | transcription repair coupling factor | √ | ||
| RP739 | IM | ADP/ATP carrier protein (tlc5) | √ | ||
| RP778 | C/OM | DNA polymerase III a chain (dnaE) | √ | ||
| RP884 | C | ferrochelatase (hemE) | √ | ||
| Orientia immunogens | Localization | Function | B | CD4+ | CD8+ |
| Sta22 | OM | TSA47, transposase/DegP-like serin protease | √ | √ | |
| Sta47 | C/P | TSA56, multi-pass membrane protein | √ | ||
| Sta56 | OM | autotransporter protein | √ | √ | |
| ScaA | OM | autotransporter protein | √ | √ | √ |
| ScaC | OM | autotransporter protein | √ | ||
| ScaD | OM | autotransporter protein | √ | ||
| ScaE | C/OM | TSA47, transposase/DegP-like serin protease | √ | ||