Table 1.

H. ducreyi mutants tested in the human challenge model.

Gene	Definition	Function	Results	Source of Mutant(Reference)
hhdB	secretion/activation of hemolysin	lyses fibroblasts	Virulent	Munson (20)
losB	D-glycero-D-manno-heptosyltransferase	extends LOS beyond KDO-triheptose-glucose	Virulent	Munson (21)
lst	lipooligosaccharide sialytransferase	adds sialic acid to major glycoform of LOS	Virulent	Munson (21)
ftpA	fine tangled pilus major subunit	unknown	Virulent	Spinola (22)
hgbA	hemoglobin binding outer membrane protein	heme/iron acquisition and transport from hemoglobin	Attenuated	Elkins (23)
momp	major outer membrane protein	OmpA homologue; minor role in fibronectin binding	Virulent	Spinola & Hansen (24)
pal	peptidoglycan associated lipoprotein	lipoprotein; OM stability	Attenuated	Spinola (25)
dsrA	ducreyi serum resistance A	OMP; major role in serum resistance	Attenuated	Elkins (26)
cdtC	cytolethal distending toxin	toxic for T cells, epithelial cells, fibroblasts	Virulent	Hansen (27)
cdtC/hhdB	double mutant, cytolethal distending toxin, hemolysin	toxic for T cells, epithelial cells, fibroblasts; lyses fibroblasts	Virulent	Hansen & Munson (27)
glu	glucosyltransferase gene	adds glucose to KDO-triheptose LOS core	Virulent	Campagnari & Munson (28)
sodC	superoxide dismutase C	detoxifies ROS for bacteria in phagolysosomes	Virulent	Kawula (29)
tadA	tight adherence protein A	type 1V secretion; secretion of Flp proteins	Attenuated	Hansen (30)
lspA1/lspA2	double mutant, large supernatant proteins	secreted proteins; prevent Fc-γRmediated phagocytosis	Attenuated	Hansen (31)
ompP2A/ompP2B	double mutant, porin proteins	encode known classical trimeric porins	Virulent	Campagnari (32)
dltA	ducreyi lectin A	OMP; partial serum resistance	Partially Attenuated	Elkins (33)
ncaA	necessary for collagen adherence	OMP; confers collagen binding	Attenuated	Kawula (34)
wecA	first enzyme in the ECA biosynthetic pathway	initiates synthesis of putative ECA glycoconjugate	Partially Attenuated	Munson (35)
tdX/tdhA	double mutant; ton B dependent receptors	heme uptake	Virulent	Elkins (36)
fgbA	putative fibrinogen binding adhesion	OMP that confers binding to fibrinogen	Partially Attenuated	Bauer & Janowicz (37)
luxS	homolog of V. harveyi luxS	Autoinducer; quorum sensing	Partially Attenuated	Hansen (38)
sapA	Susceptibility to antimicrobial peptides	Confers partial resistance to LL-37	Partially Attenuated	Bauer (39)
cpxA	Sensor kinase of CpxRA 2-component system	Uncontrolled activation of CpxR	Attenuated	Munson & Spinola (40)
flp-1,-2,-3	Fimbria-like proteins 1,2,3	Microcolony formation	Attenuated	Munson (41)
cpxR	Response Regulator of CpxRA system	Senses Extracytoplasmic Stress	Virulent	Hansen (42)
sapBC	Susceptibility to antimicrobial peptides	Confers resistance to LL-37	Attenuated	Bauer (43)
neuA	CMP sialic acid synthetase	Makes required substrate for all sialyltransferases	Virulent	Munson (44)
csrA	Carbon storage regulator	Post transcriptional regulator; affects mRNA stability and translation	Partially Attenuated	Spinola (45)
ompP4	OMP with homology to H. influenzae ompP4	putative lipoprotein expressed in vivo	Virulent	Janowicz (46)
hfq	Facilitates binding of sRNAs with mRNAs	Post transcriptional regulator	Attenuated	Spinola (47)
relA spoT double mutant	Encode enzymes for synthesis/hydrolysis of (p)ppGpp	Transcriptional regulator; mediates the stringent response to starvation	Partially Attenuated	Spinola (48)
35000HP∆PEA (HD0371, HD0852, HD1598 triple mutant)	Encode 3 putative PEA transferases	Alters LOS charge; confers resistance to α and β defensins	Virulent	Bauer (49)
dksA mutant	RNA polymerase (RNAP)-binding transcription factor	Co-regulator of RNAP with (p)ppGpp; has independent transcriptional effects	Partially Attenuated	Spinola (50)
35000HPhgbAII	class I hgbA allele replaced by a class II allele in 35000HP	Heme/iron acquisition; possible surrogate for class II strains for vaccine studies	Partially Attenuated	Leduc (51)