Serological responses to papillomavirus group-specific antigens in women with neoplasia of the cervix uteri

Seric and local antibodies against a synthetic peptide of HPV16

An ELISA method was used to detect IgG and IgA directed against a synthetic peptide derived from the E2 ORF of the human papillomavirus (HPV) 16 in sera and in cervico-vaginal secretions from 20 women without evidence of HPV infection and from 41 women with histological diagnosis of HPV infection. The proportion of IgA positive sera (63.4% in the case-group vs. 20.0% in the control-group) and secretions (48.8% in the case-group vs. 15.0% in the control-group) was significantly higher in women with HPV infection and seemed to increase with the severity of the cervical lesion. Such a difference was not found for specific IgG. Comparing, for each patient, the antibody level in the serum and in the secretions, we found that the amount of IgA was at mean 2.4 times higher in the sera than in the secretions.

Antibodies against linear and conformational epitopes of human papillomavirus type 16 that independently associate with incident cervical cancer

In a seroepidemiological study of incident cervical cancer, 94 cases and 188 population-based controls were used to evaluate the disease-association of IgG and IgA antibody responses against 6 human papillomavirus (HPV) type-16 antigens. Nine of the tested antibody responses were positively associated with cervical cancer, with odds ratios (ORs) ranging from 2.5 to 15.0. The antibody responses most strongly associated with cervical cancer were IgA against E6:10, an epitope derived from the carboxyterminal part of the HPV16 E6 [OR = 15.0, confidence intervals (CI) = 5.9-48.6], IgG against HPV16 virus-like particles (OR = 9.5, CI = 3.9-28.0) and IgG against the E1:19 epitope in the middle part of the E1 protein of HPV16 (OR = 7.7, C1 = 3.9-16.5). When the 3 serological assays that showed the strongest association with cervical cancer were combined, positivity for 2 assays was found among 52% of cases at an OR of 29.9. We conclude that antibody responses to several linear and conformational HPV epitopes are independently associated with cervical cancer and that combined analysis of several HPV antibody responses can result in better predictive values for HPV-associated cancer.

Pathogenesis of genital HPV infection

Clinical, subclinical, and latent human papillomavirus (HPV) infections are distinguished from HPV-associated neoplasia. Besides HPV additional cofactors are necessary to transform HPV infected tissue to intraepithelial or invasive neoplasia. Risk factors for the presence of HPV are high number of sexual partners, early cohabitarche, young age at first delivery, suppression and alteration of immune status, young age and hormonal influences. While the fact of a high number of sexual partners exclusively increases the risk of HPV infection, it is not known whether the other factors lead to either an increased risk for HPV infection and/or to HPV-associated neoplasia. Subclinical and latent genital HPV infections are highly prevalent. The prevalence rate depends on the sensitivity of the HPV detection system used, on age and sexual activity of the population screened, and on the number of subsequent examinations performed for each subject. Sexual transmission is the main pathway for genital HPV's, however, vertical, peripartal, and oral transmission are also possible. Seroreactivity against genital HPV may be due to an active infection or the result of contact with HPV earlier in life. Antibodies against the HPV 16 E7 protein indicate an increased risk for cervical cancer. Compared with humoral response cellular immune response is probably more important for regression of genital HPV infection: impaired cellular response is characterized by depletion of T helper/inducer cells and/or Langerhans cells and impaired function of natural killer cells and/or the infected keratinocyte. In condylomata replication and transcription of viral nucleic acids and antigen production coincide with cellular differentiation. However, the interaction between HPV and the keratinocyte on a molecular level in subclinical and latent disease is not well understood. Regression or persistence of subclinical and latent genital HPV infections as observed in longitudinal investigations show a constant come-and-go of HPV presence. Subclinical or latent cervical infections with high-risk HPV types (such as HPV 16 and 18) have an increased risk for the development of HPV-associated neoplasia.

Antibodies against papillomavirus antigens in cervical secretions from condyloma patients

Samples of cervical secretions and serum from 30 women with genital condylomas and 30 age-matched controls were tested for the presence of immunoglobulin A (IgA) and IgG antibodies against a panel of papillomavirus-derived antigens. The same cervical samples were also analyzed for presence of human papillomavirus (HPV) DNA by Southern blotting and polymerase chain reaction. By Southern blotting HPV DNA was detected in 8 of 30 patients with condylomas and 2 of 30 controls, and by the polymerase chain reaction HPV DNA was detected in 14 of 30 patients with condylomas and 5 of 30 controls. A total of 18 of 29 patients with condylomas and 8 of 28 controls had IgA antibodies in cervical secretions to an E2 synthetic peptide, and 17 of 29 patients with condylomas and 5 of 28 controls had local IgA antibodies to an E7 peptide (P < 0.025 and P < 0.005, respectively). The results suggest that measurement of local antibody production against selected HPV antigens may be useful in the study of HPV immunology and, possibly, for the diagnosis of HPV infection.

Pre- and posttreatment serum antibody responses to HPV 16 E2 and HSV 2 ICP8 proteins in women with cervical carcinoma

Serum antibodies to early proteins of human papillomavirus type 16 (HPV 16 E2 protein) and herpes simplex virus type 2 (HSV 2 ICP8) can be measured by ELISA. In the serum of 122 newly diagnosed cervical carcinoma patients and age-matched controls, enhanced IgA antibody levels to an HPV-16 E2 protein derived peptide no. 245 indicated a 9.5-fold (95% confidence limits 2.8-57.2) relative risk of cervical carcinoma. No significant risk was found with a corresponding HPV 6 E2 peptide or HSV 2 ICP8. To evaluate the HPV 16 E2 peptide as a possible tumor marker for cervical carcinoma serial postoperative serum samples were tested from 27 women with cervical carcinoma. Antibody responses to the HPV 16 E2 peptide depended on the clinical stage. Stage I and II patients showed decreasing posttreatment IgA and/or IgG antipeptide antibody levels. Stage III and IV patients initially showed decreasing antipeptide antibody levels followed by increasing levels. These patients also showed increasing IgG antibody levels to the HSV 2 ICP8. However, increasing antibody levels to the HPV 16 E2 peptide indicated significantly (P less than 0.05) worse 2-year disease free survival (recurring disease) than did stable or decreasing antibody levels. The results suggest that serum antipeptide antibodies to the HPV 16 E2 peptide no. 245 can be used for the monitoring of cervical carcinoma.

Dot blot hybridization in detection of human papillomavirus (HPV) infections in the oral cavity of women with genital HPV infections

The presence of human papillomavirus (HPV) types 2, 6, 7, 11, 13 and 16 DNA in cytologic scrapings of oral mucosa was studied in 309 women with genital HPV infections. The objective was to test the usefulness of oral mucosal scrapings (3 sequential swabs) in HPV DNA detection by dot blot hybridization. Based on hybridization with the 32P-labelled Alu-repeat probe, most samples contained more than 10(5) cells, which is an adequate number of cells for dot blot hybridization. Hybridization with 32P-labelled HPV DNA probes showed that 3.8% of the 309 women had an oral HPV infection. Of these, only 2 had clinical lesions indicative of HPV. All other oral HPV positive subjects had clinically healthy mucosa. HPV 6 was the most common (3.1%) type, followed by HPV 11 and 16 (1.1%). In 3 cases the genital mucosa harboured the same HPV type as found in the oral cavity. The results indicate that oral mucosal scraping results in adequate number of cells for dot blot hybridization with HPV DNA. Although the method is likely to result in an underestimation of latent and subclinical HPV infections, it is useful for studying the clinical HPV infections as well as other viral infections known to be present in exfoliated cells.

Antigenic and immunogenic epitopes shared by human papillomavirus type 16 and bovine, canine, and avian papillomaviruses

All types of papillomaviruses (PV) share common, so-called group-specific epitopes. To identify the major group-specific epitopes, we immunized 26 guinea pigs or rabbits with purified bovine PV type 1 (BPV), canine PV, or avian PV from the common chaffinch. The resulting hyperimmune sera, as well as a commercially available rabbit antiserum to BPV and seven monoclonal antibodies to BPV, were tested in an enzyme-linked immunosorbent assay with a set of 66 overlapping 20-amino-acid peptides representing the complete sequence of the major capsid proteins (L1 and L2) of human PV type 16 (HPV 16). Sera from the same animals before immunization were used as controls. The minimal reactive epitopes within each peptide were further characterized by testing of truncated peptides. The cross-reactive epitopes were clustered in two regions of L1, an internal region (at positions 171 to 235), which contained three epitopes, and the more reactive region at the carboxy terminus (at positions 411 to 475), which contained six epitopes. The most reactive of the HPV 16 broadly cross-reactive epitopes was a carboxy-terminal epitope which had the sequence DTYRF and which reacted with nine of the antisera to BPV, canine PV, or avian PV, with the commercially available rabbit antiserum to BPV, and also with a mouse monoclonal antibody to BPV. Antipeptide antisera to all of the HPV 16 L1 peptides and to the most antigenically reactive of their truncated analogs were made in guinea pigs. Antipeptide antisera reactive with BPV were obtained for three of the cross-reactive epitopes, and one of these antisera allowed highly sensitive detection of group-specific PV antigen by immunoperoxidase staining.

Genitoanal papillomavirus infection: diagnostic and therapeutic objectives in the light of current epidemiological observations

During the past decade a wide span of heterogeneity has been demonstrated for human papillomaviruses (HPVs), and some basic properties of the HPV genome have been revealed. The use of hybridization assays for HPV DNA detection in infected epithelia, and the recent introduction of synthetic HPV peptides for detection of type-specific circulating antibodies, have resulted in a major rethinking of HPV epidemiology. Recent data indicate that various HPVs may be transmitted perinatally during early infancy and that a long latency with periodic reactivation seems to be quite common. The present review attempts to assess recent epidemiological data with the concept of genitoanal papillomavirus infection (GPVI) as a predominantly sexually transmitted disease. Some diagnostic and therapeutic aspects are outlined with a pragmatic approach to the clinical relevance of GPVI.

Mapping of linear epitopes of human papillomavirus type 16: the E1, E2, E4, E5, E6 and E7 open reading frames

Certain types of human papillomavirus (HPV), especially HPV type 16, are associated with proliferative lesions of the cervix uteri that can progress to malignancy. In order to map the linear epitopes of the HPV-encoded proteins, we have synthesized the predicted amino acid sequences of the open reading frames (ORFs) in the early region of HPV 16, as a set of 94 synthetic 20-residue peptides overlapping each other with 5 amino acids. The peptides were tested for reactivity with IgA, IgG and IgM antibodies in the sera of 30 patients with HPV 16-carrying cervical neoplasia. The EI ORF had only low immunoreactivity, but several relatively minor epitopes were identified in the carboxyterminal part. The E2 ORF was found to contain several epitopes that were highly immunoreactive with a majority (up to 87%) of the cervical cancer patients' sera. The E4 ORF had one major, regularly IgA- and IgG-reactive epitope, whereas the E5 and E6 ORFs had only a few minor epitopes. The E7 ORF had several epitopes that were highly immunoreactive, but only with a minority of patients' sera. The 10 most immunoreactive peptides were also analyzed for immunoreactivity with 60 control sera, of which 22 were derived from patients with parotid gland tumors and 38 were derived from healthy volunteers. Most of the peptides were also immunoreactive with the control sera. However, the IgA antibodies, and to some extent the IgG antibodies, were found at much lower levels among the controls.