Table 1.
Mechanisms of immune evasion of major spirochetal lipoproteins.
| Bacteria | Role in immune evasion |
|---|---|
| Borrelia burgdorferi | Antigenic variation [VlsE proteins (118, 120, 131–134), OspC (135)] |
| Evasion of complement-mediated lysis [OspE, Erp (136–138), CspA (139)] | |
| Impairment of neutrophil function (BBA57) (140) | |
| Oral treponemes (ex. Treponema denticola) | C3b inactivation (various lipoproteins) (141) |
| Borrelia recurrentis | Antigenic variation (variable large and small protein genes and Vmp variants) (19, 110) |
| Bind to complement regulatory proteins, i.e., CFH and CFHR-1 [FhbA, BhCRASP-1, and HcpA (142–145)] | |
| Borrelia turicatae | Antigenic variation (variable large and small protein genes and Vmp variants) (19, 110) |
| Inhibit C4bp and C1-Inh, the major inhibitors of the classical and lectin pathway of complement activation (CihC) (146) | |
| Binds to human complement regulators, Factor H, CFHR-1 (HcpA) (143) | |
| Borrelia hermsii | Antigenic variation (variable large and small protein genes and Vmp variants) (19, 110) |
| Bind to complement regulatory proteins, i.e., CFH and CFHR-1 [FhbA, BhCRASP-1, and HcpA (142–145)] | |
| Leptospira interrogans | Impairment of neutrophil function (LIC11207) (147) |
| Bind to complement regulators (LigA, LigB, Len A, Len B) (148) |
Antigenic variation in borrelias may result from recombination of variable large and small protein genes. Lipoproteins may also impair mechanisms of innate immunity such as neutrophil function and complement activation. These mechanisms allow the spirochete to evade the host’s immune response and persist in the mammalian host.
BBA57, Borrelia burgdorferi A57 protein; BhCRASP-1, Borrelia hermsii complement regulator-acquiring surface protein 1; C1-Inh, human C1 esterase inhibitor; CihC, C1-inhibitor and C4bp-binding protein; C4bp, C4b-binding protein; CspA, complement regulator-acquiring surface protein-1; Erp, OspE-F-related lipoprotein; FhbA, complement factor H-binding protein; HcpA, human complement regulator and plasminogen-binding protein; LIC11207, L. interrogans serovar Copenhageni (LIC) protein 11207; LigA, leptospiral immunoglobulin-like protein A; LigB, leptospiral immunoglobulin-like protein B; OspC, outer-surface protein C; OspE, outer-surface protein E; VlsE, variable major protein-like sequence E; Vmp, variable major lipoprotein.