TABLE 2.

Requirement for encapsulation of BSA within various archaeosomes to achieve an elevated humoral response^a

Injection	BSA encapsulated	Archaeosome diam (nm)b	Anti-BSA titerc
			i.p.	i.m.
M. smithii-BSA	Yes	195 ± 77	3,443 ± 912d	909.8 ± 152d
M. smithii + BSA	No	207 ± 74	482.8 ± 127	323.9 ± 66.8
T. acidophilum-BSA	Yes	63 ± 33	1,007 ± 254d	1,925 ± 502d
T. acidophilum + BSA	No	99 ± 48	183.9 ± 65.7	271.1 ± 195
M. mazei-BSA	Yes	136 ± 59	919.3 ± 341d	1,631 ± 163d
M. mazei + BSA	No	132 ± 59	99.86 ± 8.59	12.46 ± 4.14
M. espanolae-BSA	Yes	196 ± 75	2,729 ± 581d	1,340 ± 122d
M. espanolae + BSA	No	200 ± 68	439.3 ± 68.0	202.6 ± 32.9
BSA + FA			7,588 ± 1,671	4,539 ± 349
BSA			151.7 ± 37.6	107.7 ± 48.9

^aBALB/c mice (four per group) were immunized on days 0 and 14 with archaeosomes containing encapsulated BSA (archaeosome-BSA) or with separate injections of the respective weights of empty archaeosome and BSA (archaeosome + BSA). For injections of nonencapsulated Ag, empty archaeosomes were given i.p. 7 h prior to a separate i.p. injection of BSA in PBS; for i.m. injections, BSA and empty archaeosomes were injected in separate haunches at about the same time. In all cases, 12.5 μg of BSA was administered per injection. Dry weights of archaeosomes in each immunization were 1.67 mg of M. smithii, 0.81 mg of T. acidophilum, 1.53 mg of M. mazei, and 1.35 mg of M. espanolae. T. acidophilum archaeosomes were prepared by hydration in PBS followed by French pressure cell treatment and centrifugation at 8,000 × g to discard the large archaeosomes. 

^bDiameter ± standard deviation. 

^cHumoral response (day 26) determined as titer (endpoint dilution at 0.3 optical density units) of IgG plus IgM antibodies in sera ± standard error of the mean. 

^dSignificantly different (P < 0.05) from value for the corresponding nonencapsulated group as calculated by Student's t test.