FIG. 9.

PCR detection of E. chaffeensis 16S rDNA fragment in the blood of E. chaffeensis-challenged mice previously immunized with rP28 or nonimmunized. Template DNAs were prepared from blood buffy coats (0.2 ml) of all challenged mice. The arrow shows the E. chaffeensis-specific 16S rDNA fragment (389 bp) obtained by PCR amplification. Lanes: 1, positive control (with a total DNA from DH82 cells infected with E. chaffeensis as the template); 2, negative control (PCR without template); 3 to 6, nonimmunized mice; 7 to 11, immunized mice; 12, 1-kb DNA ladder marker (GIBCO).