Liver functional enzymes. The levels of liver functional enzymes (A, glutamic oxaloacetic [GOT]; B, glumatic pyruvic transaminase [GPT]) in the sera of mice infected with NK19_mouse (as a representative of mouse-derived strains, white circles) or NK19_soil (as a representative of soil-derived strains, gray circles) were measured (N = 6, duplicate). After 2 d, no data were collected from the mice infected with NK19_mouse because all the mice died. After 14 d of primary infection with NK19_soil (arrows), the mice were reinfected with a mouse-derived strain (NK19_mouse, white triangles; NKcd_mouse, white squares) or a soil-derived strain (NK19_soil, gray triangles; NKcd_soil, gray squares).