Table 3.

Evaluation of Salmonella vaccine strains expressing antigen(s) of Y. pestis

Strain	Genotype	Antigen(s)	Immunization route	Protective efficacy	Reference
S. Typhimurium
SL3261	aroA	F1	i.v. or oral	i.v. immunization provides complete protection/oral immunization provides 90% protection against 50 LD50s of Y. pestis GB strain s.c. challenge	[289]
SL3261	aroA	F1/V fusion	i.v.	provides 85% protection against 50 LD50s of Y. pestis GB strain s.c. challenge	[170]
SL3261	aroA	F1 expressed under different promoters	oral	ND (serum antibody responses to F1 reported)	[290]
SL3261	aroA	LcrV	oral	provides 30% protection against 97 LD50s of Y. pestis GB strain s.c. challenge	[171]
SL3261 SLDAPD	aroA	F1	oral	oral immunization provides complete protection against 8.8 × 104 LD50s of Y. pestis GB strain s.c. challenge	[291]
H683	asd aroA	F1 and/or LcrV	oral	90% protection against ~1000LD50 Y. pestis 195/P s.c. challenge and 90% protection against ~100LD50 Y. pestis Madagascar	[119]
χ8501	hisG Δcrp-28 ΔasdA16	F1 or LcrV	i.n. or oral	3 doses of strain synthesizing F1 or LcrV provided 80% or 60% protection against 2×103 CFU of Y. pestis (Yokohama-R strain) i.p. challenge, respectively	[292]
χ8501	hisG Δcrp-28 ΔasdA16	Truncated LcrV (aa131-aa327) and Psn	oral	Truncated LcrV and Psn immunization provide 80% protection against 3000 CFU of Y. pestis CO92 and 75% protection against 1300 CFU of Y. pestis CO92 by s.c. challenge	[174]
χ9447	Complex genotypea Strain displays “regulated in vivo lysis”	LcrV196 on “runaway-like replication plasmid”	oral	Oral immunization provides 87.5% survival post-s.c. challenge with 4.49 ×102 CFU or 5.63×103 CFU of Y. pestis CO92. Oral immunization shows great efficacy with 75% and 50% survival post-i.n. challenge with 4.1×103 CFU or 4.4×104 CFU of Y. pestis CO92, respectively.	[293]
χ9558	Complex genotypeb	PsaA	oral	No protection against s.c. challenge with 4.49 ×102 CFU of Y. pestis CO92 and 25% protection against i.n. challenge with 4.1×103 CFU of Y. pestis CO92	[184]
χ8501	hisG Δcrp-28 ΔasdA16	Psn, HmuR, LcrV196 LcrV5214	oral	Immunization with the strain expressing Psn or LcrV196 afforded nearly full protection against s.c challenge and partial protection against i.n. challenge. While immunization with the strain expressing LcrV5214 or HmuR no protection against s.c. or i.n challenge.	[175]
χ9558	Complex genotypeb
S. Typhi
BRD1116	aroA aroC htrA	F1	i.n.	intranasal immunization provides 65% protection against 113 CFU of Y. pestis GB strain s.c. challenge	[176]
ACAM948CVD (CVD 9080)	htrA, aroC, aroD	F1	i.n.	~80% protection against i.v. challenge with 10,000 CFU of Y. pestis EV76 in 0.2 ml of sterile PBS. FeCl2 (40 μg/mouse) was administered i.p. immediately.	[177]
CVD 910FV	guaBA and htrA	F1, LcrV	i.n.	mice receiving the optimized bivalent vaccine were fully protected against lethal pulmonary challenge	[294]

Note: Y. pestis GB, LD₅₀ (s.c.) = 1CFU [285]; Y. pestis 195/P, LD₅₀ (s.c.) = 1CFU [295]; Y. pestis Madagascar, LD₅₀ (i.n.) ~100 CFU [295]; Y. pestis (Yokohama-R strain), LD₅₀ (i.p.) = 15 CFU [296]; Y. pestis EV76, LD₅₀ (i.v.) =56 CFU [177]; Y. pestis CO92, LD₅₀ (s.c.) =1.9 CFU, LD₅₀ (i.n.) ~250 CFU, LD₅₀ (aerosol) ~2100 CFU [65, 287, 288];

CFU: Colony forming units; LD₅₀: 50% lethal dose; s.c.: Subcutaneous; i.n.: Intranasal; i.v. Intravenous; i.p.: Intraperitoneal; ND: no detected.

^aΔpmi-2426 Δ(gmd-fcl)-26 ΔP_fur81::TT araC P_BAD fur ΔP_crp527::TT araC P_BAD crp ΔasdA21::TT araC P_BAD c2 ΔaraE25 ΔaraBAD23 ΔrelA198::araC P_BAD lacI TT ΔP_murA7::TT araC P_BAD murA ΔendA2311

^bΔpmi-2426 Δ(gmd-fcl)-26 ΔP_fur81::TT araC P_BAD fur ΔP_crp527::TT araC P_BAD crp ΔasdA27::TT araC P_BAD c2 ΔaraE25 ΔaraBAD23 ΔrelA198::araC P_BAD lacI TT ΔsopB1925 ΔagfBAC811