Table 1.
Type IV secretion (T4S) systems and disease manifestations
| Bacterial species | T4S system | Target-cell or host alterations | References |
|---|---|---|---|
| Conjugation | |||
| Escherichia coli F plasmid (IncF) | Tra | Genetic exchange | 2 |
| Escherichia coli RP4 (IncP) | Trb | Genetic exchange | 28 |
| Escherichia coli R388 (IncW) | Trw | Genetic exchange | 28 |
| Shigella Collb-P9 (IncI) | Tra | Genetic exchange | 28 |
| *Agrobacterium tumefaciens | VirB | Crown gall/genetic exchange | 11 |
| *Legionella pneumophila | Dot/Icm | Genetic exchange | 5 |
| DNA uptake and release | |||
| Campylobacter jejuni | Cjp/VirB | DNA uptake | 6 |
| Helicobacter pylori | ComB | DNA uptake | 18 |
| Neisseria gonorrhoeae | Tra | DNA release | 8 |
| Effector translocation | |||
| Agrobacterium tumefaciens | VirB | Crown gall | 11 |
| Helicobacter pylori | Cag | Gastritis, peptic ulcer | 4 |
| Bordetella pertussis | Ptl | Whooping cough | 45 |
| Legionella pneumophila | Dot/Icm | Legionnaire’s pneumonia | 5 |
| Brucella spp. | VirB | Brucellosis | 105 |
| Bartonella spp. | VirB, Trw | Cat-scratch, angiomatosis | 26,72 |
| ‡Actinobacillus | MagB | Periodontitis | 106 |
| ‡Ehrlichia spp. | VirB | Ehrlichiosis | 107 |
| ‡Wolbachia spp. | VirB | Host sexual alterations | 108 |
| ‡Rickettsia spp. | – | Epidemic typhus, Mediterranean spotted fever | 109 |
| ‡Xylella fastidiosa | VirB | Leaf scorch disease, citrus variegated chlorosis | 110 |
| ‡Coxiella burnetii | Dot/Icm | Q fever | 111 |
*
These systems have been shown to function both as conjugation machines, transferring DNA to bacterial recipients, and as effector translocators, delivering effector molecules to eukaryotic target cells during infection.
‡
These systems are presumed to be functional T4S systems on the basis of sequence similarities with conjugation systems.