title: Comparisons of VLP-Based ELISA, Neutralization Assays with Native HPV, and Neutralization Assays with PsV in Detecting HPV Antibody Responses in HIV-Infected Women.
abstract: OBJECTIVE
  Human papillomavirus (HPV)-associated cancers are important public health problems in HIV-infected people. Assays based on HPV virus-like particles (VLP) and pseudoviruses (PsV) are commonly used to examine HPV antibody responses in HIV-infected people, but neutralization assays with native HPV have not been utilized and a comparison of these three assays is lacking. We evaluated the agreement of assays using VLP, native HPV and PsV in detecting HPV16 and 18 antibodies in HIV-infected women.
  
  
  METHODS
  The VLP-based ELISA (VLP-ELISA) was used to detect antibody responses to HPV16 and 18 and cottontail rabbit papillomavirus (CRPV) VLP antigens. Neutralization assays with native HPV (NA-HPV) and with PsV (NA-PsV) were conducted to examine HPV16 or 18 neutralizing antibodies. Intra class correlation coefficients (ICC) and kappa coefficients were used to assess the agreements of seropositivity between the assays.
  
  
  RESULTS
  The seroprevalence detected by the VLP-ELISA, NA-HPV and NA-PsV in 94 HIV-infected women was 35%, 51% and 27% for HPV16 and 14%, 44% and 21% for HPV18. Cross-reactivity between HPV16 and HPV18 was 0.35, 0.04 and 0.33 (kappa coefficients) for the VLP-ELISA, NA-HPV and NA-PsV. The agreements of seropositivity between the three assays were low. Six women who were HPV16 DNA positive were seropositive by the NA-HPV but only two were HPV16 seropositive by the VLP-ELISA or NA-PsV. One HPV18 DNA positive woman was seropositive by all three assays. Repeated tests indicated excellent reproducibility of the NA-HPV.
  
  
  CONCLUSIONS
  HPV serology results vary across different assays. The NA-HPV appears to be a sensitive and reliable approach in detecting natural HPV antibodies in HIV-infected women. The NA-HPV can be applied in both HPV natural history studies and vaccine studies in HIV-infected people.
authors.affiliation: Department of Medicine, The Pennsylvania State University College of Medicine, USA ; Department of Public Health Sciences, The Pennsylvania State University College of Medicine, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Du
authors.affiliation: Department of Pathology, The Pennsylvania State University College of Medicine, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Brendle
authors.affiliation: Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, USA.
authors.forename: Janice
authors.initials: J
authors.lastname: Milici
authors.affiliation: Department of Public Health Sciences, The Pennsylvania State University College of Medicine, USA.
authors.forename: Fabian
authors.initials: F
authors.lastname: Camacho
authors.affiliation: Department of Medicine, The Pennsylvania State University College of Medicine, USA.
authors.forename: John
authors.initials: J
authors.lastname: Zurlo
authors.affiliation: Department of Pathology, The Pennsylvania State University College of Medicine, USA.
authors.forename: Neil
authors.initials: N
authors.lastname: Christensen
authors.affiliation: Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Meyers
keywords: ELISA; HIV-infected women; Human papillomavirus; Neutralization assay; Pseudoviruses; Virus-like particles