Table 1.

Strategies for Persistence

Bacterial Pathogen	TLR evasion	Complement evasion	Secretion Systems
Brucella spp.	Modified lipid A moiety LPS (TLR4) Flagellin lacks TLR5 recognition moiety (TLR5) Btp1/TcpB protein degrades MAL (TLR2, TLR4)	O-antigen portion of LPS modification avoids C3 binding and release of anaphylatoxins C3a C5a	T4SS-mediated lysosome evasion and trafficking to endoplasmic reticulum
S. typhi	Expression of Vi-capsule (TLR4) TviA-mediated downregulation of flagellin (TLR5) TviA-mediated down regulation of T3SS1 (surface TLR2, TLR4)	Expression of Vi-capsule inhibits C3 binding and release of anaphylatoxins C3a C5a Vi-capsule inhibition of C3b binding and complement-mediated phagocytosis by neutrophils Vi-capsule inhibition of C5a-dependent neutrophils chemotaxis	T3SS1: downregulated during systemic infection T3SS2: mediates lysosome evasion and intracellular survival