Constructing conjugate vaccine against Salmonella Typhimurium using lipid-A free lipopolysaccharide

Table 1 Carbohydrate-to-protein molar ratio and estimated conjugation number of the synthesized PS − protein conjugates

Entry	PS–protein conjugate^a	PS μg/mL (μM)^b	Protein μg/mL (μM)^c	Conjugation number^d
1	7a (BSA)^e	168.7 (1.97)	62.4 (0.95)	2–3 (2.1)^d
2	7a (BSA)^f	98.2 (4.27)	13.2 (0.20)	20–23 (21.8)^d
3	7b (OVA)^e	342.2 (3.99)	123.0 (2.80)	1–2 (1.4)^d
4	7c (FliC)^{f, g}	168.4 (7.32)	24.0 (0.47)	14–17 (15.6)^d
5	8a (BSA)^f	94.1 (4.09)	13.8 (0.21)	18–21 (19.5)^d
6	8b (FliC)^{f, h}	235.5 (10.24)	83.1 (1.63)	5–7 (6.3)^d
7	9a (BSA)^f	95.4 (4.15)	15.2 (0.23)	17–19 (18.0)^d
8	9b (FliC)^{f, h}	221.0 (9.61)	96.8 (1.90)	4–6 (5.1)^d

^a PS−protein conjugates prepared from S. Typhimurium LFPS, and isolated by FPLC−SEC
^b Data derived from PSA assay by calibration of the absorbance at 490 nm
^c Data derived from BCA assay by calibration of the absorbance at 562 nm based on the molecular weights of OVA (44 kDa), BSA (66 kDa) and FliC (51 kDa)
^d Estimated number of LFPS on each PS–protein conjugate. Data in parenthesis are calculated from the molar ratio of PS over protein
^e The PS−protein conjugate was prepared from fraction-1 LFPS with a median molecular weight of 85.8 kDa
^f The PS−protein conjugate was prepared from unfractionated LFPS with average molecular weight of 23 kDa
^g Conjugate 7c was prepared by the coupling reaction of PS−A−B/Np with FliC
^h The azido-modified FliC was prepared by site-selective method, and used in synthesis of 8b and 9b

ISSN: 1423-0127