TABLE 8.

Protective efficacy of sera from mice immunized with PspA-cytokine fusions after challenge with capsular type 3 strain WU2^a

Route of injection	Antigen	Serum dilutionb	Results of pneumococcal challenge
			No. of days alive	No. alive:no. dead	P value vs PspA onlyc
s.c.	PspA (amino acids 1–243)	1:5	2, 2, 2, 2	0:4	NA
		1:10	2, 2, 2	0:3
		1:30	2, 2, 2, 2	0:4
	PspA–IL-2	1:5	>21, >21, >21, >21	4:0	0.0007
		1:10	2, >21, >21	2:1	0.033
		1:30	>21, >21, >21, >21	4:0	0.0007
		1:90	>21, >21, >21, >21	4:0	0.0007
i.n.	PspA (amino acids 1–243)	1:5	2, 2, 2, 3	0:4	NA
		1:10	2, 2, 2	0:3
		1:30	2, 2, 2, 2	0:4
	PspA–GM-CSF	1:5	>21, >21, >21, >21	4:0	0.0007
		1:10	>21, >21, >21	3:0	0.033
		1:30	2, >21, >21, >21	3:1	0.088
		1:90	>21, >21, >21, >21	4:0	0.0007
None (Ringer’s solution)			2, 2, 2, 2, 3	0:4	NS

^aIgG antibody levels (micrograms/milliliter) to PspA in immune serum produced by immunization with PspA (s.c.), PspA-IL2 (s.c.), PspA (i.n.), and PspA-GMCSF (i.n.) were <0.3, 400, <0.3, and 156, respectively. Levels for IgA were <0.3, 8.5, <0.3, and 14.5; levels for IgM were <0.5, 2.7, <0.5, and 2.6. 

^bSera were diluted in Ringer’s solution. 

^cCalculated versus pooled PspA only for the same injection route by Fisher’s exact test; NA, not applicable; NS, not significant, P ≥ 0.05.