Detection of antibodies against rhEPO in sera of cynomolgus macaques treated with pseudotyped AAV2CMVrhEPO vector. The animals in Figure 1 that developed anemia were evaluated for rhEPO antibodies. (A) AAV2/1, 17108. (B) AAV2/5, 17111. (C) AAV2/5, 17112. (D) AAV2/8, 17148. Growth inhibition of the EPO-dependent cell line HCD57 in the presence of a constant dilution of macaque serum is represented on the right y-axis (solid lines, ▪) as cell viability measured by cell proliferation assay. Binding of antibody to EPO and interference of its detection is illustrated on the left y-axis (dotted lines, □) as percentage of EPO detected in the presence of antisera in comparison with that detected in the standard EPO assay. Ten-fold diluted antisera were used for both assays. The impact of sera on these assays, drawn at different times following vector, are shown.