Figure 6.

Role of antibodies against recombinant proteins from immunized lambs in the inhibition of A. phagocytophilum infection of HL60 human cells. Sheep IgG antibodies against A. phagocytophilum MSP4 and MSP4-HSP70 recombinant proteins were obtained from control and immunized sheep at 0 and 94 dpi and used to characterize the inhibition of pathogen infection of HL60 human cells. Treatments included purified IgGs from rabbit pre-immune, anti-MSP4 and anti-HSP70 sera. Purified IgGs were mixed with A. phagocytophilum inoculum of human NY18 isolate for 60 min before being placed on the cell monolayers. A. phagocytophilum infection levels were determined by msp4 real-time PCR normalizing against human β-actin. Results were compared between groups treated with pre-immune/control and anti-MSP4/HSP70 antibodies by the Student's t-test with unequal variance (^*P < 0.05; N = 4 replicates per treatment).