Evaluation of alum-based adjuvant on the immunogenicity of salmonella enterica serovar typhi conjugates vaccines

Figures & data

Table 1. Characterization of vaccines based on WHO TRS 987.

		Vi-DT			Vi-TT
Item	Requirement	AlPO	AlOH	PBS	AlPO	AlOH	PBS
Sterility	Sterile	Sterile	Sterile	Sterile	Sterile	Sterile	Sterile
O-acetyl content (µmol/dose)	Min 0.085	69.67 ± 1.37	67.83 ± 1.13	69.00 ± 2.24	67.00 ± 0.45	66.83 ± 0.52	67.67 ± 0.93
Molecular Weight (kDa)	No requirement	1830.67 ± 18.25	1830.67 ± 18.25	1830.67 ± 18.25	1917.33 ± 36.40	1917.33 ± 36.40	1917.33 ± 36.40
pH	6.5 – 7.5	7.26 ± 0.03	7.17 ± 0.03	7.03 ± 0.02	7.23 ± 0.04	7.19 ± 0.01	7.04 ± 0.05
Endotoxin (EU/µg Vi)	No requirement	8.52 ± 0.52	8.39 ± 0.62	8.33 ± 0.54	9.49 ± 0.51	9.04 ± 1.10	9.49 ± 0.51
Vi content (µg/dose)	21.25 – 28.75	25.16 ± 0.91	25.56 ± 0.53	25.72 ± 0.90	25.10 ± 0.50	25.58 ± 0.20	25.23 ± 0.90
Free Vi (%)	No requirement	21.72 ± 2.11	21.40 ± 2.35	21.26 ± 2.14	21.80 ± 2.41	21.41 ± 2.70	21.67 ± 2.16
Osmolality (mosmol/Kg)	250 – 350	343.03 ± 2.64	345 ± 3.22	344.01 ± 2.35	341.33 ± 5.96	337.67 ± 4.93	340.33 ± 4.59
Identity	Polysaccharide +	Polysaccharide +	Polysaccharide +	Polysaccharide +	Polysaccharide +	Polysaccharide +	Polysaccharide +
Adsorption (%)	No Requirement	75.00 ± 1.79	84.33 ± 1.37	NP	11.00 ± 0.89	26.33 ± 1.37	NP

Vi-DT : Vi conjugated with Diphtheria Toxoid;

Vi-TT : Vi conjugated with Tetanus Toxoid;

AlPO : Adjuvant Aluminum phosphate;

AlOH : Adjuvant Aluminum hydroxide;

PBS : Phosphate Buffer Saline;

NP : Not performed.

Table 2. Anti-Vi IgG immune responses in mice.^a

	Level of Anti Vi IgG After 1st Injection^c			Level of Anti Vi IgG After 2nd Injection^c
Products^b	Geometric Mean Anti-Vi IgG (95% confidence interval)	Median^†	Average Rank^† (Overall 15.5)	Geometric Mean Anti-Vi IgG (95% confidence interval)	Median^†	Average Rank^† (Overall 15.5)
Vi-DT (AlPO)	23.851 ± 4.933	23.85	16.20	39.105 ± 18.266	39.10	13.80
Vi-DT (AlOH)	28.697 ± 3.995	28.70	20.60	43.953 ± 20.362	43.95	16.80
Vi-DT (PBS)	14.339 ± 1.190	14.34	3.00	22.526 ± 1.302	22.53	10.8
Vi-TT (AlPO)	49.219 ± 11.523	49.22	28.00	104.966 ± 80.648	104.97	23.00
Vi-TT (AlOH)	25.901 ± 1.765	25.90	17.20	137.008 ± 35.674	137.01	25.60
Vi-TT (PBS)	16.961 ± 0.350	16.96	8.00	17.337 ± 0.617	17.34	3.00
AlPO	0.034 ± 0.035	NA	NA	0.035 ± 0.039	NA	NA
AlOH	0.020 ± 0.000	NA	NA	0.020 ± 0.000	NA	NA

^† Test was done using Kruskal-Wallis test.

^a Six week old male and female mice were injected intramuscularly with two dose products, dose were given 0 and 2 weeks.

^b Vi-DT (AlPO) : Vi conjugated with Diphtheria Toxoid and added adjuvant Aluminum phosphate in the final product;

Vi-DT (AlOH) : Vi conjugated with Diphtheria Toxoid and added adjuvant Aluminum hydroxide in the final product;

Vi-DT (PBS): Vi conjugated with Diphtheria Toxoid and added Phosphate Buffer Saline in the final product;

Vi-TT (AlPO): Vi conjugated with Tetanus Toxoid and added adjuvant Aluminum phosphate in the final product;

Vi-TT (AlOH): Vi conjugated with Tetanus Toxoid and added adjuvant Aluminum hydroxide in the final product;

Vi-TT (PBS) : Vi conjugated with Tetanus Toxoid and added Phosphate Buffer Saline in the final product;

AlPO: Adjuvant Aluminum phosphate;

AlOH: Adjuvant Aluminum hydroxide.

^c Bleeds were taken at 2 (1^st) and 4 (2^nd) weeks and sera assayed for Vi antibodies.

Table 3. %CD4+ expressing IL4, IL2, IL10 and IFN-γafter receiving 2 doses of vaccines.

	%CD4+ (95% confidence interval)
Products^a	IL2	IL4^b	Aveage rank^† (Overall 15.5)	IL10	Aveage rank^† (Overall 15.5)	IFN-γ	Aveage rank^† (Overall 15.5)
Vi-DT (AlPO)	ND	53.4 ± 7.86	17.6	74.5 ± 19.7	17.4	91.4 ± 8.66	23.2
Vi-DT (AlOH)	0.68 ± 1.00	56.1 ± 7.86	20.2	88.5 ± 19.7	24.0	88.0 ± 8.66	18,8
Vi-DT (PBS)	1.39 ± 2.77	44,5 ± 10.4	10.4	71.6 ± 12.9	17.6	62,3 ± 18.9	7.4
Vi-TT (AlPO)	0.93 ± 1.00	49.1 ± 6.79	14.2	56.2 ± 11.2	8.3	90.6 ± 9.84	21.8
Vi-TT (AlOH)	1.43 ± 1.00	65.6 ± 9.25	26.4	56.2 ± 11.2	8.3	82.6 ± 7.23	15.8
Vi-TT (PBS)	0.38 ± 2.72	34.5 ± 2.83	4.2	71.2 ± 10.9	17.4	66.8 ± 0.50	6.0

^† Test was done using Kruskal-Wallis test.

^a Vi-DT (AlPO) : Vi conjugated with Diphtheria Toxoid and added adjuvant Aluminum phosphate in the final product;

Vi-DT (AlOH) : Vi conjugated with Diphtheria Toxoid and added adjuvant Aluminum hydroxide in the final product;

Vi-DT (PBS) : Vi conjugated with Diphtheria Toxoid and added Phosphate Buffer Saline in the final product;

Vi-TT (AlPO) : Vi conjugated with Tetanus Toxoid and added adjuvant Aluminum phosphate in the final product;

Vi-TT (AlOH) : Vi conjugated with Tetanus Toxoid and added adjuvant Aluminum hydroxide in the final product;

Vi-TT (PBS) : Vi conjugated with Tetanus Toxoid and added Phosphate Buffer Saline in the final product;

ND : Not Determined.

^b IL-4 : Interleukin 4;

IL-2 : Interleukin 2;

IL-10 : Interleukin 10;

IFN-γ : Interferon Gamma.