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. 2012 Jul;19(7):1075–1082. doi: 10.1128/CVI.00139-12

Table 2.

In vitro neutralization titers for sera from immune animalsa

Assay and serum pool Neutralization titer for virus
HPV16 HPV31 HPV33 HPV45 HPV58
L2-based assay
    PBS, pool 1 <50 <50 <50 <50 <50
    PBS, pool 2 <50 <50 <50 <50 <50
    HPV16 VLP, pool 1 172,080 <50 <50 <50 <50
    HPV16 VLP, pool 2 306,550 <50 <50 <50 <50
    L2 11-88×5, pool 1 7,500 50 4,315 2,780 5,370
    L2 11-88×5, pool 2 13,760 765 4,130 2,640 4,025
    L2 11-88×5, pool 3 4,095 <50 <50 365 700
    L2 11-88×5, pool 4 10,730 7,865 27,145 7,805 13,820
    L2 11-88×5, pool 5 20,900 2,600 1,605 5,890 3,395
    L2 11-88×5, pool 6 27,630 480 210 5,005 10,940
    L2 11-88×5, pool 7 3,420 190 22,385 1,375 1,140
L1-based assay
    PBS, pool 1 <50 <50 <50 <50 <50
    PBS, pool 2 <50 <50 <50 <50 <50
    HPV16 VLP, pool 1 7,600 <50 <50 <50 <50
    HPV16 VLP, pool 2 60,605 <50 <50 <50 <50
    L2 11-88×5, pool 1 <50 <50 <50 <50 <50
    L2 11-88×5, pool 2 <50 <50 <50 <50 <50
    L2 11-88×5, pool 3 <50 <50 <50 <50 <50
    L2 11-88×5, pool 4 <50 <50 50 50 <50
    L2 11-88×5, pool 5 <50 <50 <50 50 <50
    L2 11-88×5, pool 6 <50 <50 50 <50 <50
    L2 11-88×5, pool 7 <50 <50 150 50 <50
P value, 1-7 (L2-based vs L1-based assay) 0.001 0.011 0.012 0.002 0.001
a

Cross-neutralization titers obtained with “L1-based” and “L2-based” assays. Sera were obtained from mice that had been immunized with L2 (11-88×5) and shown to be immune to in vivo challenge with HPV16, -31, -45, or -58. Sera from 5 animals that underwent identical treatment were pooled and assessed for in vitro neutralization with the newly described L2-based neutralization assay or the “L1-based” assay. As specificity controls, pooled sera from HPV16 VLP-immunized animals were also assayed. The assay was performed in duplicate, and the average titer is shown. Triplicate experiments were not possible due to limited sample volume. The bottom row indicates the P value of the difference between the two groups of 7 pools for each virus type. Titers that were found to be <50 were assigned a value of 25 for statistical analysis. The P value is based on the Mann-Whitney test with Gaussian approximation.