title: A novel HPV 16 L1-based chimeric virus-like particle containing E6 and E7 seroreactive epitopes permits highly specific detection of antibodies in patients with CIN 1 and HPV-16 infection.
abstract: BACKGROUND
  The presence of IgG antibodies to HPV-16 L1-virus like particles (VLPs) in serum has been reported as a result of persistent exposure to the virus and as a marker of disease progression. However, detection of VLP-specific antibodies in sera does not always indicate a malignant lesion as positive results may also be due to a nonmalignant viral infection. Furthermore, malignant lesions are associated with an increased antibody titer for E6 and E7 proteins. The aim of this study was to develop an ELISA using a novel chimeric virus-like particle (cVLP) encoding an L1 protein fused with a string of HPV-16 E6 and E7 seroreactive epitopes to its C-terminus to be used for detection of HPV-16 specific antibodies in patients with cervical intraepithelial lesion grade 1 (CIN 1).
  
  
  RESULTS
  The sera of 30 patients with CIN 1 who also tested positive for HPV-16 DNA and of 30 age-matched normal donors negative for HPV infection were tested for the presence of IgG antibodies specific for either VLP-L1 (HPV-16 L1), gVLP (derived from Gardasil), or cVLP by ELISA. The cVLP-reactive sera yielded two distinct groups of results: (H) reactivity levels that presented very strong cVLP-specific titers, and (L) reactivity levels with significantly lower titers similar to those obtained with VLP-L1 and gVLP antigens. Additionally, the sera that presented the higher cVLP titers closely matched those that had significantly stronger reactivity to E6 and E7 epitopes. Interestingly, the samples with the highest titers corresponded to patients with the higher numbers of sexual partners and pregnancies. On the other hand only 4 out of the 12 sera that harbored antibodies with VLP neutralizing ability corresponded to the group with high cVLP antibody titers.
  
  
  CONCLUSIONS
  We report for the first time that chimeric particles containing HPV-16 L1 protein fused with E6 and E7 seroreactive epitopes enable much better detection of IgG antibodies in the sera of CIN 1 patients positive for HPV-16 infection than those obtained with VLPs containing only the HPV-16 L1 protein. We also found that the sera with higher cVLP antibody titers corresponded to patients with more sexual partners and pregnancies, and not always with to those with a high neutralizing activity. This novel assay could help in the development of a tool to evaluate cervical cancer risk.
authors.affiliation: Unidad de Investigación Médica en Enfermedades Oncológicas, IMSS, CMN SXXI, México. albertomon@yahoo.com
authors.forename: Alberto
authors.initials: A
authors.lastname: Monroy-García
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Gómez-Lim
authors.forename: Benny
authors.initials: B
authors.lastname: Weiss-Steider
authors.forename: Georgina Paz-de
authors.initials: GP
authors.lastname: la Rosa
authors.forename: Jorge
authors.initials: J
authors.lastname: Hernández-Montes
authors.forename: Karyna
authors.initials: K
authors.lastname: Pérez-Saldaña
authors.forename: Yessica S
authors.initials: YS
authors.lastname: Tapia-Guerrero
authors.forename: Mariel E
authors.initials: ME
authors.lastname: Toledo-Guzmán
authors.forename: Edelmiro
authors.initials: E
authors.lastname: Santiago-Osorio
authors.forename: Héctor I
authors.initials: HI
authors.lastname: Sanchez-Peña
authors.forename: María de Lourdes
authors.initials: Mde L
authors.lastname: Mora-García
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D036022:Capsid Proteins / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D005260:Female; D052162:Human papillomavirus 16 / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008875:Middle Aged; D009856:Oncogene Proteins, Viral / Q000276:immunology; D050725:Papillomavirus E7 Proteins / Q000276:immunology; D030361:Papillomavirus Infections / Q000175:diagnosis*; D011993:Recombinant Fusion Proteins / Q000276:immunology; D012097:Repressor Proteins / Q000276:immunology; D012680:Sensitivity and Specificity; D002583:Uterine Cervical Neoplasms / Q000821:virology*; D014773:Virology / Q000379:methods; D022701:Virosomes / Q000276:immunology; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D036022:Capsid Proteins; C068651:E6 protein, Human papillomavirus type 16; D018985:Epitopes, B-Lymphocyte; D007074:Immunoglobulin G; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D022701:Virosomes; C059731:oncogene protein E7, Human papillomavirus type 16; C063317:L1 protein, Human papillomavirus type 16