Fig 1.

Neutralization of HPV16 (filled circles), HPV18 (filled triangles), HPV31 (open circles), HPV45 (open triangles), and control BPV (asterisks) pseudoviruses by using individual plasmas. HPV16, HPV18, and BPV neutralization titers were assembled using data generated by both laboratories A and B, while HPV31 and HPV45 titers were determined by laboratory A only. Negative values (<40) were assigned a titer of 20, and a maximum level was assigned when titers were ≥10,000. Plasma samples are arranged according to whether they were selected for inclusion in the high HPV16/18 (P02, P06, P09, P14, P22, P24, and P25), intermediate HPV16/18 (P18 and P21), and HPV-negative (P03, P04, P12, and P19) antibody pools.