title: Determinants of seropositivity among HPV-16/18 DNA positive young women.
abstract: BACKGROUND
  Not all women infected with HPV-16/18 have detectable levels of HPV-16/18 antibodies, those who seroconvert develop low antibody levels, and seroconversion occurs typically several months post-infection. We evaluated determinants of seropositivity among 646 women infected with HPV-16 and/or HPV-18.
  
  
  METHODS
  Data are from the enrollment visit of the NCI-sponsored Costa Rica HPV Vaccine Trial. Sera were tested for HPV-16/18 antibodies by ELISA; cervical specimens were tested for HPV DNA using HC2 and SPF10/LiPA25. Odds ratios (OR) and 95% confidence intervals (CI) were computed.
  
  
  RESULTS
  Among HPV-16/18 DNA positives, seropositivity was 63.0% and 57.5%, respectively. Among HPV-16 DNA positives, seropositivity increased with lifetime number of sexual partners (p-trend = 0.01). Women with abnormal cytology and/or high viral load had a 1.63-2.79-fold increase in the detection of antibodies compared to women with normal cytology/low viral load. Current users of oral contraceptives had a 1.88-fold (95%CI, 1.14-3.09) increased detection of antibodies and current users of injectables had a 3.38-fold (95%CI, 1.39-8.23) increased detection compared to never users. Among HPV-18 DNA positive women, seropositivity was associated with current oral contraceptive use (OR 2.47; 95%CI 1.08-5.65).
  
  
  CONCLUSIONS
  Factors associated with sustained HPV exposure (abnormal cytology, elevated HPV viral load, increasing lifetime partners) were predictive of HPV-16 seropositivity. Hormonal contraceptive use was associated with seropositivity suggesting an effect of hormones on immune responses to HPV. Patterns were less consistent for HPV-18. Follow up of incident HPV infections to evaluate seroconversion and their determinants is needed.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, USA. cporras@proyectoguanacaste.org
authors.forename: Carolina
authors.initials: C
authors.lastname: Porras
authors.forename: Christina
authors.initials: C
authors.lastname: Bennett
authors.forename: Mahboobeh
authors.initials: M
authors.lastname: Safaeian
authors.forename: Sarah
authors.initials: S
authors.lastname: Coseo
authors.forename: Ana Cecilia
authors.initials: AC
authors.lastname: Rodríguez
authors.forename: Paula
authors.initials: P
authors.lastname: González
authors.forename: Martha
authors.initials: M
authors.lastname: Hutchinson
authors.forename: Silvia
authors.initials: S
authors.lastname: Jiménez
authors.forename: Mark E
authors.initials: ME
authors.lastname: Sherman
authors.forename: Sholom
authors.initials: S
authors.lastname: Wacholder
authors.forename: Diane
authors.initials: D
authors.lastname: Solomon
authors.forename: Leen-Jan
authors.initials: LJ
authors.lastname: van Doorn
authors.forename: Catherine
authors.initials: C
authors.lastname: Bougelet
authors.forename: Wim
authors.initials: W
authors.lastname: Quint
authors.forename: Mark
authors.initials: M
authors.lastname: Schiffman
authors.forename: Rolando
authors.initials: R
authors.lastname: Herrero
authors.forename: Allan
authors.initials: A
authors.lastname: Hildesheim
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D002584:Cervix Uteri / Q000821:virology; D003364:Costa Rica / Q000453:epidemiology; D004279:DNA, Viral / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D052162:Human papillomavirus 16 / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D052161:Human papillomavirus 18 / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D030361:Papillomavirus Infections / Q000453:epidemiology* / Q000276:immunology / Q000821:virology; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D004279:DNA, Viral