Table 1.
Overview of A. baumannii virulence factors reported in this review.
| Gene(s) | Virulence Factor(s) | Function(s) | Reference |
|---|---|---|---|
| K locus | capsule | Persistence | [44] |
| OC locus | Lipo-oligosaccharide (LOS) | Dryness resistance | [45] |
| csuA/BABCDE | Csu pili | Biofilm formation | [46] |
| bap | Bap | Biofilm formation | [47] |
| M215_09430 locus | Repeats-in-Toxin (RTX)-like domain | Biofilm formation | [12] |
| pgaABCD locus | PNAG | Biofilm formation | [48] |
| recA | RecA | DNA damage repair | [49] |
| katG | KatG | Oxidative stress resistance | [50] |
| katE | KatE | Oxidative stress resistance | [50] |
| abuO | AbuO (component of an ABC efflux pump) | Oxidative stress response | [51] |
| adeABC | AdeABC (RDN efflux pump) |
Osmotic stress resistance | [52] |
| emrAB | EmrAB (MFS efflux pump) |
Osmotic stress resistance | [53] |
| abeD | AbeD (component of an RND-type efflux pump) |
Osmotic stress resistance | [54] |
| amvA | AmvA (component of an MFS efflux pump) | Resistance to disinfectants | [55] |
| aceI | AceI (component of a PACE efflux pump) | Resistance to disinfectants | [56] |
| abaI | AbaI (component of the QS system) | Virulence, motility, conjugation, biofilm formation and host-pathogen interactions | [57] |
| abaR | AbaR (component of the QS system) | Virulence, motility, conjugation, biofilm formation and host-pathogen interactions | [57] |
| bfmS | BfmS | QS-regulated two-component system involved in biofilm formation | [58] |
| bfmR | BfmR | QS-regulated two-component system involved in biofilm formation | [58] |
| pilA | PilA (major pilin of type IV pili) |
Twitching motility and evasion of the host immune system | [59] |
| ompA | OmpA | Antibiotic- and serum-resistance, biofilm formation, host-interaction, cytotoxicity, interference with autophagy and apoptosis | [60,61,62,63,64,65,66,67] |
| carO | CarO | Resistance to carbapenems | [68,69,70] |
| omp33 | Omp33 (also known as Omp33-36 kDa or Omp34) |
Induction of apoptosis and modulation of autophagy | [71,72] |
| occAB1 | OccAB1 (also known as OprD-like or porinD) |
Uptake of antibiotics and iron, host-interaction | [70,73,74,75,76] |
| ompW | OmpW | Iron uptake and cytoxicity | [77] |
| Acinetobactin gene cluster | Acinetobactin | Iron chelator | [78] |
| Fimsbactins gene cluster | Fimsbactins A-F | Iron chelators | [78] |
| Baumannoferrin gene cluster | Baumannoferrin A-B | Iron chelators | [78] |
| fur | Fur | Iron metabolism transcriptional regulator | [79] |
| plc1 and plc2 | PLC | Lipolytic activity for iron acquisition | [80] |
| pld1-3 | PLD | Lipolytic activity for iron acquisition | [81] |
| oxyR | OxyR | ROS response regulator | [82] |
| soxR | SoxR | Superoxide response regulator | [83] |
| znuA, znuCB, znuD1 and znuD2 | ZnuA, ZnuB, ZnuC, ZnuD1 and ZnuD2 | Uptake of zinc | [84] |
| zur | Zur | Zinc metabolism transcriptional regulator | [84] |
| zigA | ZigA | Zinc metallo-chaperone | [85] |
| mumT | MumT | Uptake of manganese | [86] |
| pit | PIT system | Low affinity phosphate uptake system | [87] |
| pst operon | PstS | High affinity phosphate uptake system | [88] |
| phoB and phoR | PhoB and PhoR | Two-component regulatory system for phosphate uptake | [89] |
| hlyB, hlyD and tolC | HlyB, HlyD and TolC (T1SS) |
Secretion of proteins involved in biofilm formation and adhesion to pulmonary epithelia | [12] |
| gsp genes | T2SS | Secretion of proteins from the Sec or the Tat translocons | [90] |
| tra locus | T4SS | Conjugative transfer of DNA, plasmids, and other mobile genetic elements | [91] |
| AbfhaB and AbfhaC | AbFhaB and C (T5bSS) |
Adhesion to integrin and fibronectin | [92] |
| cdiA1, cdiB1, cdiA2 and cdiB2 | CdiA and B (T5bSS) |
Killing of bacterial competitors | [93] |
| ata | Ata (T5cSS) |
Adhesion to collagen I, III, IV, V and laminin | [94] |
| Core, accessory and regulatory genes | T6SS | Contact-dependent secretion of substrates into competitor bacterial or eukaryotic cells | [95] |
| None | OMVs | Long-distance delivery of multiple packaged virulence factors | [96] |