Previous studies showed that PAV3 does not exhibit crossreactivity with AdHu5 or BAV3 neutralizing antibodies [20, 21] . Additionally, PAV3 was not neutralized by the lowest dilution of 1:4 from 50 randomly selected human sera [20] In order to further address neutralization of PAV3 by an extended number of human sera, human Ig made of pooled sera from 10,000-60,000 individuals was evaluated. AdHu5, used as a control, was neutralized at the highest dilution of 1:160 (6.25610 23 mg/ml human Ig). In contrast, neutralization of PAV3 was not detected at 1:20 (5.061022 mg/ml), the lowest dilution tested. Previous studies showed little cross-reactivity between cell-mediated immune responses against AdHu5 and PAV3 [22] .