Table 1. Differential expression of Y. pestis pathogenesis-related genes in the flea.

Gene or system	Description/function	Expression level in flea relative to*:
		Flow cell	Exp. phase	Stat. phase	Bubo
Outer surface components
caf1R	F1 capsule gene regulator	f	f	f	−2.4
caf1M	F1 capsule periplasmic chaperone	f	f	f	−20
caf1A	F1 capsule outer membrane usher	7.1	5.3	4.0	−36
caf1	F1 capsule subunit protein	6.8	5.0	4.5	−42
pla	plasminogen activator	0.9	1.0	0.8	−1.5
yadB	YadA-like protein	f	f	f	1.1
yadC	YadA-like protein	2.7	3.3	1.9	f
psaE	pH 6 antigen regulator	−4.4	−7.9	−20	−12.6
psaF	pH 6 antigen hypothetical protein	1.2	1.0	−2.7	−0.8
psaA	pH 6 antigen fimbrial subunit	ns	ns	ns	b
psaB	pH 6 antigen chaperone	ns	ns	ns	ns
psaC	pH 6 antigen usher	3.4	3.4	2.5	−0.6
lpxP	hexaacylated lipid A synthesis	2.2	3.4	3.2	1.8
msbB	hexaacylated lipid A synthesis	1.5	1.6	1.4	2.2
Iron acquisition systems
Ybt	yersiniabactin siderophore, 10 genes	1.5–4.2	−1.4–1.8	−4.6–1.0	−15–−84
Yfe	ABC iron transporter, 5 genes	−1.4–1.8	−1.6–1.3	−1.4–1.6	−1.2–−14
Toxins
yitR	positive regulator of yitABC	10.3	47	23	f
yitABC	insecticidal-like toxin complex	5.6–11	21–27	8.8–10	17–25
yipB	insecticidal-like toxin complex	4.0	10	5.6	2.2
Global regulatory systems
rovA	regulator of virulence factors	−7.3	−6.6	−5.9	−1.4
rovM	repressor of rovA	9.1	7.1	5.9	11.1
phoP	regulator of PhoPQ regulon	2.1	2.2	2.2	2.3
Other
mgtC	survival in macrophages	3.0	5.9	4.3	10.0
mviM	Salmonella mouse virulence factor	2.4	2.9	1.5	2.9

*: f, expression detected in flea but not comparison condition; b, expression detected in bubo but not flea; ns, no expression detected in flea or comparison condition.