title: Antibody avidity measurements in recipients of Cervarix vaccine following a two-dose schedule or a three-dose schedule.
abstract: The HPV-16/18 vaccine (Cervarix) is a prophylactic vaccine for the prevention of cervical cancer and contains recombinant virus-like particles (VLPs) assembled from the L1 major capsid proteins of human papillomavirus (HPV) strains 16 and 18. Although a correlate of protection has yet to be identified, HPV-specific antibodies are thought to prevent virus infection of the genital mucosa. Therefore, antigen-specific antibodies as assessed by ELISA or pseudovirion-based neutralisation assay are frequently measured in clinical trials to substantiate the immune responses induced by the vaccine. Measuring antigen-antibody binding avidities, which reflects the degree of affinity maturation in the B-cells, is another valuable method to assess the quality of the antibody responses. Here we describe the antigen-specific antibody avidities in samples taken from a clinical trial examining the feasibility of adopting a two-dose (Months 0 and 6) schedule for 9-14 year olds instead of the three-dose schedule (Months 0, 1 and 6). Antibody avidity (i.e. avidity index [AI]) was determined in the ELISA by the ratio of antibody concentrations in serum samples treated or not with the chaotropic agent NaSCN. Importantly, in the comparison between the groups of two-dose and three-dose recipients, no differences in AIs were observed at Months 7, 24 and 48. The results suggest that from Month 7 to 48, the quality of the antibody response in terms of avidity was similar in the two-dose recipients to that in the three-dose recipients. Hence these results support the adoption of a two-dose schedule in 9-14 year-old girls.
authors.affiliation: GlaxoSmithKline Vaccines, Rue de l'Institut 89, 1330 Rixensart, Belgium.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Boxus
authors.affiliation: GlaxoSmithKline Vaccines, Rue de l'Institut 89, 1330 Rixensart, Belgium.
authors.forename: Laurence
authors.initials: L
authors.lastname: Lockman
authors.affiliation: GlaxoSmithKline Vaccines, Rue de l'Institut 89, 1330 Rixensart, Belgium.
authors.forename: Michel
authors.initials: M
authors.lastname: Fochesato
authors.affiliation: GlaxoSmithKline Vaccines, Rue de l'Institut 89, 1330 Rixensart, Belgium.
authors.forename: Clarisse
authors.initials: C
authors.lastname: Lorin
authors.affiliation: GlaxoSmithKline Vaccines, Rue de l'Institut 89, 1330 Rixensart, Belgium.
authors.forename: Florence
authors.initials: F
authors.lastname: Thomas
authors.affiliation: GlaxoSmithKline Vaccines, Rue de l'Institut 89, 1330 Rixensart, Belgium. Electronic address: sandra.giannini@gsk.com.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Giannini
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D000915:Antibody Affinity; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007115:Immunization Schedule; D008875:Middle Aged; D030361:Papillomavirus Infections / Q000517:prevention & control; D053918:Papillomavirus Vaccines / Q000276:immunology*; D016032:Randomized Controlled Trials as Topic; D002583:Uterine Cervical Neoplasms / Q000517:prevention & control; D058425:Vaccines, Virus-Like Particle / Q000276:immunology; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D053918:Papillomavirus Vaccines; D058425:Vaccines, Virus-Like Particle; C510352:human papillomavirus vaccine, L1 type 16, 18
keywords: Antibodies; Avidity; Cervical cancer; Human papillomavirus; Vaccine