Human Papillomavirus Antibody Reference Reagents for Use in Postvaccination Surveillance Serology

Centre for Infections, Health Protection Agency, London, United Kingdom.
Clinical and vaccine Immunology: CVI (Impact Factor: 2.37). 03/2012; 19(3):449-51. DOI: 10.1128/CVI.05641-11
Source: PubMed

ABSTRACT Suitably controlled serosurveillance surveys are essential for evaluating human papillomavirus (HPV) immunization programs. A panel of plasma samples from 18-year-old females was assembled, the majority of the samples being from recipients of the bivalent HPV vaccine. Antibody specificities were evaluated by three independent laboratories, and 3 pools that displayed no antibodies to any HPV type tested or intermediate or high levels of antibody to HPV16, HPV18, HPV31, and HPV45 were created. These pools will be useful as control reagents for HPV serology.

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    ABSTRACT: For middle and low-income countries, the cost of HPV vaccines remains challenging. We conducted an open-label nonrandomized clinical trial evaluating immune response to the HPV-16/18 AS04-adjuvanted vaccine administered on a standard (months (M) 0-1-6) versus extended schedule (M 0-6-60) at 7, 21, 60, 72 and 120 months post-vaccination. Participants were females recruited in Morelos, Mexico: 474 girls aged 9-10 years and 500 women aged 18-24 years receiving a standard schedule, and 1026 girls aged 9-10 years receiving an extended schedule (currently the girls in the extended schedule had received only the first 2 doses). This report presents the interim analysis results for non-inferiority between the regimes conducted with the current available data at 21 months after the first dose, with serum antibodies assessed by ELISA. A pre-stated margin of non-inferiority was defined by post-vaccination geometric mean titer (GMT) ratio (upper 95% confidence interval [CI]≤2.0) between the standard and the two-dose schedule in girls at month 21. Immune response to the vaccine was strongest in adolescent girls and in the 3-dose group. Statistical non-inferiority of the two-dose versus three-dose groups was demonstrated. At 21 months, comparing the adolescent 2-dose versus 3-dose groups, the GMT ratio and 95% CI were 1.66 (1.55-1.81) and 1.67 (1.51-1.86) for HPV16 and 18, respectively. The two-dose regimen was non-inferior when compared to the three-dose response in same-age girls and with women aged 18-24 years after 21 months of follow-up. The reduction in the number of doses from the current three-dose schedule may lower overall costs associated with the vaccination and increase accessibility and compliance with the recommended dosing of the HPV vaccine.
    Vaccine 12/2013; DOI:10.1016/j.vaccine.2013.11.059 · 3.49 Impact Factor
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    ABSTRACT: We assessed HPV 16 and 18 antibody responses of female subjects enrolled in a 2- vs. 3-dose quadrivalent HPV (Q-HPV) vaccine trial ( NCT00501137) using the Merck competitive Luminex (cLIA) and total IgG Luminex (TIgG) immunoassays, and a pseudovirus neutralizing antibody (PsV NAb) assay. Subjects were enrolled in one of three groups: (1) 9-13yr, 2 doses of Q-HPV at 0, 6 months (n=259); (2) 9-13yr, 3 doses at 0, 2, 6 months (n=260); and (3) 16-26yr, 3 doses at 0, 2, 6 months (n=305). Sera were collected from all subjects at baseline, months 7 and 24, and from half the subjects at months 18 and 36. High correlation was observed between all three assays. At month 36, HPV 16 antibodies remained detectable in all subjects by all assays, whereas 86.4%, 99.6% and 100% of subjects respectively were HPV 18 cLIA, TIgG and PsV NAb (partial neutralization endpoint) seropositive. The proportion seropositive for HPV 18 by cLIA at 36 months was not significantly different for 2-dose girls vs. 3-dose adults (85.9% vs. 79.4%; p=0.51), whereas the proportion for 3-dose girls was significantly higher than for 3-dose adults (95.3% vs. 79.4%; p<0.01). The HPV 18 seropositive proportions by the TIgG and PsV NAb (partial neutralization endpoint) assays were the same for all subjects. High baseline HPV 16 and HPV 18 seropositivity was observed for the TIgG assay and it is unclear if all the detected TIgG antibodies are type-specific and/or neutralizing. For the PsV NAb assay, 90% and partial neutralization geometric mean titres were consistently 2-8-fold higher than for 100% neutralization, which enabled detection of HPV 18 NAb in subjects who lost detectable cLIA antibodies over time. We conclude that the PsV NAb assay is more sensitive than the cLIA, and likely more specific than the TIgG assay.
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