TABLE 1.

A. phagocytophilum organisms in BALB/c mouse blood following homologous and heterologous challenge

Group no.	Original isolate	Challenge isolate	7 days PCH		14 days PCH		21 days PCH
			No. of PCR-positive mice (n = 6)	No. of organismsa	No. of PCR-positive mice (n = 6)	No. of organisms	No. of PCR-positive mice (n = 6)	No. of organisms
1	Dawson	None	0	0	0	0	0	0
2	Dawson	Dawson	6	3,944 ± 3,292	0	0	2	93 ± 144
3	Dawson	Gaillard	6	2,380 ± 2,626	3	196 ± 258	0	0
4	None	Dawson	6	11,893 ± 9,251	5	3,241 ± 6,723	6	5,150 ± 4,940
5	Gaillard	None	0	0	0	0	0	0
6	Gaillard	Gaillard	5	3,572 ± 5,083	3	213 ± 439	0	0
7	Gaillard	Dawson	6	1,156 ± 672	4	62 ± 55	0	0
8	None	Gaillard	6	62,563 ± 47,591	2	73 ± 150	5	6,409 ± 6,906

^aAverage number of A. phagocytophilum organisms per 100 μl of whole blood ± standard deviations.