Figure 2. . . Western blot analyses, using recombinant P44-1 protein (rP44-1) and Anaplasma phagocytophilum–infected THP-1 cells as antigens, of serum samples from 2 men, case-patients 1 and 2, who had A. phagocytophilum infection, Kochi Prefecture, Japan. The Escherichia coli, which produced rP44-1, was kindly provided by Yasuko Rikihisa (Ohio State University, Columbus, OH, USA). The rP44-1 and the rabbit hyperimmune serum (positive control serum) were prepared as described (11,12). Results for a negative control (human serum sample) are included. The primary human serum samples tested were diluted 200- to 400-fold; rabbit serum sample (positive control) was diluted 2,000-fold. The goat antihuman IgG and IgM alkaline phosphatase conjugates (Life Technologies, Grand Island, NY, USA) were used as secondary antibodies. Days represent days after symptom onset. rP, rP44-1 antigen; In, infected THP-1; Un, uninfected THP-1 cells.