The malaria blood stage antigen PfCyRPA formulated with the TLR-4 agonist adjuvant GLA-SE elicits parasite growth inhibitory antibodies in experimental animals

Table 3 Humoral immune responses elicited in New Zealand rabbits by adjuvanted formulations of recombinant PfCyRPA

Adjuvant	Dose of adjuvant	Dose of PfCyRPA (µg)	Rabbit #	ELISA serum endpoint titer	Concentration of purified IgG giving half-max binding in ELISA [µg/mL]	GIA IC₅₀ [mg/mL]
GLA-LSQ	25 µg GLA; 10 µg QS-21	40	1	2,048,000	0.65	2.1
GLA-LSQ	25 µg GLA; 10 µg QS-21	40	2	2,048,000	0.31	1.6
GLA-SE	25 µg GLA; 2% squalene	40	1	8,192,000	0.11	1.0
GLA-SE	25 µg GLA; 2% squalene	40	2	2,048,000	0.33	0.3
GLA-Alum	25 µg GLA; 500 µg Alum	40	1	2,048,000	0.43	3.3
GLA-Alum	25 µg GLA; 500 µg Alum	40	2	2,048,000	0.61	3.7
No adjuvant	–	40	1	128,000	1.34	N/A
No adjuvant	–	40	2	1000	16.51	N/A

Shown are ELISA IgG endpoint titers of individual serum samples collected after the third immunization and the concentration of purified total IgG that gives half-maximal binding in ELISA. GIA IC₅₀ values: The concentrations of purified IgG giving 50% growth inhibition in GIA were determined in a standardized [³H]-hypoxanthine incorporation assay. Shown are mean values of two independent assays (Fig. 2i–l)

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