Assessment of HPV 16 and HPV 18 antibody responses by pseudovirus neutralization, Merck cLIA and Merck total IgG LIA immunoassays in a reduced dosage quadrivalent HPV vaccine trial

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 (ClinicalTrials.gov 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.

Amino acid motifs in both the major and minor capsid proteins of HPV51 impact antigenicity and infectivity

“…These data also corroborate recent observations of poor concordance between the VLP ELISA and the pseudovirus neutralization assay for measuring NI antibodies (Safaeian et al, 2012) in contrast to the generally good concordance for measuring vaccine-induced typespecific antibody (Dessy et al, 2008;Krajden et al, 2014). On a technical level, these data suggest that pseudoviruses should be considered the preferred antigen for such studies.…”

“…A limited number of serological assays are available for measuring vaccine type-specific antibody responses, including an L1 VLP ELISA, a mAb competitive VLP assay and an L1L2 pseudovirus neutralization assay. Despite some discrepancies, overall inter-assay agreements are good (Dessy et al, 2008;Krajden et al, 2014). Natural infection (NI) studies usually compare the HPV DNA status of individuals with their respective antibody status in order to better understand the pathogen-host relationship.…”

“…Most of these studies have made use of an immobilized L1-based target (Carter et al, 2000;Castellsagué et al, 2014;Safaeian et al, 2010;Syrjänen et al, 2009;Wilson et al, 2013;Xi et al, 2002), whilst a few have used an L1L2 pseudovirus neutralization assay (Lin et al, 2013;Ochi et al, 2008;Pastrana et al, 2004). Inter-assay agreements for measuring NI antibody responses appear to be quite poor (Safaeian et al, 2012), in contrast to studies of vaccine antibody responses (Dessy et al, 2008;Krajden et al, 2014). There also appears to be a poor correlation between the presence of HPV DNA and type-specific antibody in contemporary samples (Carter et al, 2000;Ochi et al, 2008;Pastrana et al, 2004;Syrjänen et al, 2009;Wilson et al, 2013).…”

Immunogenicity of quadrivalent HPV and combined hepatitis A and B vaccine when co-administered or administered one month apart to 9–10 year-old girls according to 0–6 month schedule

“…The assay performance was validated using 140 blinded specimens which were previously 21 HPV antibody titers are reported in Luminex Units (LU). Anti-HBs was measured by the MONOLISA Anti-HBs EIA and MONOLISA Anti-HBs Calibrator Kit (Bio-Rad Laboratories).…”

Naturally Occurring Major and Minor Capsid Protein Variants of Human Papillomavirus 45 (HPV45): Differential Recognition by Cross-Neutralizing Antibodies Generated by HPV Vaccines

“…HPV PsVs have been used widely to monitor antibody responses to vaccines and natural infection (18,22,32,39,40), as well as to elucidate steps in the entry process (41). Nevertheless differences between how PsVs behave in vitro and how authentic HPV45 lineage variants behave in vivo are uncertain, although this is a limitation of all PsV-based systems.…”