TABLE 1.

Virulence factors encoded by chromosomal Shigella PAIs

PAIGene(s)Biochemical activityVirulence function(s)Reference(s)
SHI-1 sigA Immunoglobulin A-like cytopathic proteaseIntestinal fluid accumulation, cytopathic toxin 5
pic Serine protease, mucinaseMucus permeabilization, serum resistance, hemagglutination 105
set1A, set1BEnterotoxin ShET1Intestinal fluid accumulation, development of watery diarrhea 70, 71
SHI-2 iucA to iucD, iutASiderophore (aerobactin) production and transportIron acquisition 177, 182, 322
shiD UnknownColicin I and colicin V immunity
shiA UnknownDownregulation of inflammation by suppression of T-cell signaling 116, 117
SHI-3 iucA to iucD, iutAAerobactin production and transportIron acquisition (found only in S. boydii) 227
SHI-O gtrA, gtrB, gtrVModification of O antigens, serotype conversionEvasion of host immune response 113, 115
SRL fecA to fecE, fecI, fecRFerric dicitrate uptakeIron acquisition 154, 314
tetA to tetD, tetREfflux systemTetracycline resistance
cat AcetyltransferaseChloramphenicol resistance
oxa-1 β-LactamaseAmpicillin resistance
aadA1 AdenylyltransferaseStreptomycin resistance