A phagocytophilum infection is severely compromised in Fuc-TIV^-/-/Fuc-TVII^-/- mice. (A) PCR amplification of A phagocytophilum DNA in the blood of Fuc-TIV^-/-/Fuc-TVII^-/- mice and wild-type mice. A murine blood sample previously determined to contain A phagocytophilum DNA served as a positive control (indicated as “+”). (B) Percentage of peripheral blood neutrophils with morulae containing A phagocytophilum. Data are presented as the mean percentage (± SD) of morulae-positive neutrophils. The difference in the percentages of neutrophils infected for wild type mice versus Fuc-TIV^-/-/Fuc-TVII^-/- mice was statistically significant on days 5, 7, and 21 after infection (^*P < .05). (C) Fc-Oxyburst assay of A phagocytophilum-infected murine leukocytes. Leukocytes from A phagocytophilum-infected Fuc-TIV^-/-/Fuc-TVII^-/- and control mice were incubated with Fc-Oxyburst immune complexes (10 μg/mL). The amount of oxidative species generated by the cells was measured as the fluorescence signal at 530 nm. Assays were performed in triplicate. Data are presented as the mean percentage (± SD) of NADPH oxidase competent cells. Representative data from at least 2 studies are presented.