TABLE 1.

Parasite dissemination in IE-LACK transgenic mice during the early phase of infection

Organ	No. of positive mice/no. of mice testedb at:
	20 h		38 h		3 days		6 days
	IE-LACK	BALB/c	IE-LACK	BALB/c	IE-LACK	BALB/c	IE-LACK	BALB/c
Spleen	0/2	1/2	1/9	7/9	1/2	2/2	2/2	2/2
Liver	0/2	0/2	0/9	5/9	0/2	1/2	1/2	2/2

^aIE-LACK transgenic mice and BALB/c mice were infected with 2 × 10⁶ stationary-phase L. major promastigotes subcutaneously into both footpads. At different times after infection, spleens and livers from individual mice were harvested and analyzed for the presence of parasites using PCR as described earlier (8). Briefly, DNA was isolated from tissue homogenates using the InstaGene DNA purification matrix. To detect Leishmania DNA from live parasites by PCR, two primers (primer 1, 5′-GTGGGGAGGGGGCGTTCT-3′; primer 2, 5′-ATTTTACACCAACCCCCAGTT-3′) were used for amplification of the 120-bp fragment of the minicircle kinetoplast DNA of L. major. Briefly, 20 μl of extracted DNA were mixed with 0.5 pmol of each primer, a 200 μM concentration of each deoxynucleoside triphosphate, 50 mM KCl, 1.5 mM MgCl₂, 10 mM Tris-HCl (pH 9.0), and 0.1 U of Taq DNA polymerase in a total volume of 100 μl. The sample was submitted to 27 cycles of amplification (94°C for 30 s, 50°C for 45 s, 72°C for 60 s) in an automated DNA, thermal cycler (Perkin-Elmer Cetus). PCR products were analyzed by gel electrophoresis in a 2% agarose gel. 

^bThat is, the number of mice in which L. major was detected by PCR/the total number of tested animals.