TABLE 2.

NO₂⁻ and TNF-α production in J774.A1 cells infected with different strains of Brucella or coinfected with B. suis GFP and a Brucella rough mutant

Infectiona	Production ofb:
	NO2− at 48 h (μM)	TNF-α at 24 h (ng/ml)
B. suis 1330	1.9 ± 0.5*	0.7 ± 0.5*
B. suis manb	27.7 ± 1.7†‡	28.7 ± 1.5†‡
B. melitensis 16M	3.0 ± 1.1*	0.5 ± 0.3*
B. melitensis R5	22.0 ± 3‡§	10.0 ± 2‡§
B. melitensis B3B2	16.3 ± 3.7‡§	30.7 ± 1.4‡§
B. suis GFP	2.3 ± 0.5*	0.5 ± 0.2*
B. suis GFP + manb	24.8 ± 0.9∥	24.9 ± 5.3∥
B. suis GFP + B. melitensis B3B2	18.2 ± 3.7∥	27.8 ± 2.5∥
E. coli LPS + IFN-γ	43.2 ± 3.1‡	37.5 ± 3.1‡
None	0.2 ± 0.2	0.7 ± 0.4

^aJ774.A1 cells (10⁶/well) were infected (or not) with different smooth or rough Brucella strains (MOI = 40) or cultured with 100 ng of E. coli LPS plus 2 U of mouse recombinant IFN-γ per ml. In parallel experiments, cells were infected with B. suis GFP (MOI = 40) in the absence or presence of B. suis manb (or B. melitensis B3B2) (MOI = 40). At the indicated periods of time, cell supernatants were harvested and their NO₂⁻ or TNF-α contents were determined (21). The data presented are means ± standard deviations of three different experiments. Comparisons between different assays were performed by using unpaired Student's t tests.

^b*, not significant compared to nontreated cells; †, P < 0.001 compared to B. suis 1330; ‡, P < 0.001 compared to nontreated cells; §, P < 0.001 compared to B. melitensis 16M; ∥, P < 0.001 compared with values obtained in infections with B. suis GFP alone.