TABLE 1

Virulence factors of Bartonella spp.

Virulence factor(s)Direct function(s)Contribution(s) to pathogenesis
Trimeric autotransporter adhesins (BadA, Vomps)Bacterial autoaggregation, attachment to extracellular matrix, host cell binding via β1-integrins, activation of HIF-1 and NF-κB, inhibition of macrophage phagocytosisStable interaction with host cell as basis for further manipulation, secretion of proangiogenic cytokines
VirB/D4 type IV secretion system, Bartonella effector proteinsInhibition of apoptosis, proinflammatory activation, modulation of angiogenesis, invasome formationSetup and control of intracellular niche
Unknown factor (probably surface protein)Activation of cellular signaling via β1-integrinsTriggering host cell invasion in course of invasome formation
Outer membrane proteinsActivation of NF-κB signaling, host cell adhesionSecretion of MCP-1 and upregulation of E-selectin and ICAM-1 (as part of proangiogenic signaling?)
Secreted factor (GroEL)Unknown, activation of Ca2+ signaling?Inhibition of apoptosis and mitogenic stimulation of host cells
Trw type IV secretion systemAdhesion to erythrocyte surfaceEnabling erythrocyte invasion (lineage 4)
DeforminFormation of invaginations in erythrocyte membranesEnabling erythrocyte invasion
FlagellationMechanical force?Invasion of erythrocytes (lineages 1-3)
Invasion-associated locus (IalAB)UnknownInvasion of erythrocytes
LipopolysaccharidesInvisibility to TLR4, antagonizing TLR4 signalingImmune evasion and immunomodulation
AutotransportersUnknown, cohemolysin activity (Cfa)?Unknown
Filamentous hemagglutininsUnknownUnknown
Hemin binding proteinsHemin binding, fibronectin binding (HbpA)Host cell adhesion?, formation of a heme surface layer (antioxidant barrier? nutritive reservoir?)
OMP43Fibronectin binding, host cell bindingHost cell adhesion?