TABLE 1.

Pathogens with T3SSs and their effects on the host

PathogenT3SS componentsHostsRelationship with hostsDiseases caused by agent
Structural proteins/ translocatorsEffectors
Yersinia species (Y. pestis, Y. enterocolitica, Y. pseudotuberculosis)Ysc injectisome, YopB, YopD, LcrVYopH, -E, -T, and -O and YpkA, -P/J, and -MHumans, cattle, rodents, fleas (Y. pestis)PathogenPlague (bubonic, pneumonic, and septicemic) (Y. pestis), enterocolitis and mesenteric lymphadenitis (Y. enterocolitica and Y. pseudotuberculosis)
Salmonella enterica serovars (Typhimurium, Typhi, Paratyphi, Sendai, Dublin, and Choleraesuis)SPI1, PrgK, PrgH, InvG (ring base), PrgI (needle), and SipB/C/D (putative translocators); SPI2, Ssa proteins (apparatus), Ssc proteins (effector chaperones), SsrAB (regulators), and SseB/C/D (translocators)SPI1, AvrA, SipA/B/C/D, SlrP, SseK, SopA/B/D/E/E, and SptP; SPI2, SpiC, SseF/G/I/J, SlrP, SspH1/H2, SifA, SifB, PipB/B2, SseK1/K2, GogB, and SopD2Humans, rodents, chickens, cows, and pigsPathogen (in humans, rodents, cows, and pigs), innocuous carriage (in chickens and some human cases)Enterocolitis in humans and typhlitis and typhoid-like disease in mice (serovar Typhimurium), enteric fever in humans (serovars Typhi, Paratyphi, and Sendai), intestinal inflammation and bacteremia in cows (serovar Dublin), septicemia in pigs (serovar Choleraesuis)
EPEC/EHECEspA/B/D (translocators)Tir, Map, Nle's, EspF/G, Cif, Orf3Humans, cows, calvesPathogen (in humans and calves), innocuous carriage (in cows)Intestinal inflammation and bloody diarrhea (EPEC/EHEC), possibility of renal failure and septic shock (EHEC)
Shigella species (S. dysenteriae, S. flexneri, S. boydii, and S. sonnei [multiple serotypes])Mxi/Spa (apparatus), IpaB/C (translocators), IpgC (IpaB/C chaperone)IpaA/B, C terminus of IpaC, VirA, IpaH, Osp's, IpgB1Humans (only known reservoir)PathogenBacillary dysentery (shigellosis), sporadic dysentery pandemics (S. dysenteriae)
Bordetella species (B. pertussis, B. parapertussis, and B. bronchiseptica)aBopB, BopD (potential translocators)BopCHumans, dogs, pigsPathogenWhooping cough (B. pertussis and B. parapertussis [milder with B. parapertussis]), kennel cough in dogs, atrophic rhinitis in swine, possible respiratory illness in humans (B. bronchiseptica)
Pseudomonas aeruginosa PopB and PopD (translocators), PcrV, SpcU (chaperon for ExoU)ExoS, ExoT, ExoU, ExoYPart of normal flora in up to 20% of humans, common in the environmentOpportunistic and nosocomial pathogenPneumonia (common cause of hospital-acquired pneumonia and occasionally of community-acquired pneumonia), chronic airway infection in cystic fibrosis, urinary tract infections in long-term care facilities, various other clinical infections (e.g., endocarditis) in immunocompromised patients
Burkholderia pseudomallei T3SS-1, T3SS-2, T3SS-3 (Bsa)BopAB (putative), BopE (T3SS-3)Environmental isolate, humansHuman pathogenMelioidosis, community-acquired bacteremias and pneumonias
Vibrio parahaemolyticus, V. choleraeT3SS1 (V. parahaemolyticus), T3SS2 (V. parahaemolyticus and V. cholerae)VP1680 (T3SS1), VopA (T3SS2)Aquatic isolate, humansHuman pathogensNoninflammatory secretory diarrhea (V. cholerae), inflammatory diarrhea with potential systemic spread (V. parahaemolyticus)
Chlamydia speciesYscN (ATPase), LcrH1 and -2 and SycE (chaperones), LcrE (structural “lid”)IncA and additional Inc proteins, Cpn0909, Cpn1020Obligate intracellular pathogens, infectious bodies found in the environmentHuman pathogens (C. trachomatis and C. pneumoniae), bird pathogen (C. psittaci)Sexually transmitted infection (C. trachomatis), pneumonia (C. pneumoniae), psittacosis in birds (C. psittaci)
  • a Also carry the T3SS components BopN and Bsp22 (whose functions are unknown).