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Serum Antibodies to Human Papillomavirus 16 Proteins in Women from Brazil with Invasive Cervical Carcinoma¹

Department of Pediatrics, Stanley Division of Developmental Neurovirology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287 [Y. S., B. C., R. P. V.]; Department of Preventive Medicine, Faculdade de Medicina, Universidade de Sao Paulo, 455 Sao Paulo-SP, CEP 01246, Brazil [J. E-N.]; Institut Catala d‘Oncologia, 08907, Barcelona Spain [F. X. B.]; Unit of Field and Intervention Studies, International Agency for Research on Cancer, Lyon 69372, France [N. M.]; Department of Pathology, Free University Hospital, Amsterdam 1081 HV, the Netherlands [J. M. M. W., C. J. L. M. M.]; and Department of Molecular Medicine and Immunology, Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland 21205 [K. V. S.]

	Abstract

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Serum samples from 194 cases and 217 controls participating in a case-control study of invasive cervical cancer in Brazil were examined for antibodies to human papillomavirus (HPV) 16 virus-like particles (VLPs) by ELISA. The prevalence of antibody in cases and controls was 47.4 versus 24.4% (P < 0.001). The prevalence was higher in women who had HPV-16 DNA in the genital tract (54.2%) than in those with other HPVs (36.8%) or no HPVs (44.8%), but the differences were not statistically significant. Among cases and controls, HPV-16 VLP antibodies were associated with a greater number of lifetime sexual partners (² for trend, P < 0.001). Among controls, age was inversely associated with HPV-16 VLP seroreactivity (² for trend, P = 0.019). The sera were previously tested for antibodies to HPV-16 E6 and E7 oncoproteins; there was no correlation between antibody titers to HPV-16 E6 or E7 and VLPs. The HPV-16 serological assays were compared as screening tests for invasive cervical cancer. The sensitivity and specificity estimates were 47.4 and 75.6% for HPV-16 VLP serology, 63.4 and 89.9% for either HPV-16 E6 or E7 serology, and 53.6 and 93.6% for high titers of either HPV-16 E6 or E7 or VLP antibodies. The utility of HPV-16 VLP ELISA as a screening test for invasive cervical cancer is limited by a high seroprevalence in women with probable prior exposure to HVP 16 but without disease.

	Introduction

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The etiological role of HPV³ infections in cervical cancer is now well established. The evidence that linked cervical cancers to HPVs is based almost exclusively on analyses of HPV DNA sequences in the uterine cervix. It has been more difficult to identify immunological markers of HPV infections and of HPV-associated invasive cervical cancer. Recently, several investigators have reported that HPV VLPs, prepared by expression of L1 or L1 and L2 genes in baculovirus or vaccinia virus systems, are suitable reagents for the measurement of antibody response to HPV infections in an ELISA (1, 2, 3) . The antibody response to HPV infections, as measured by ELISA with VLPs, is low titered and type specific but is not detectable in all individuals with documented infections (4, 5, 6) . In one study, the proportion of infected individuals who develop anti-VLP antibodies varied from 22% in women who had a transient infection to 83% in women who had a persistent infection (7) . Higher antibody response is also related to the presence of a higher amount of HPV DNA in the cervix (4 , 6) .

We have previously reported the results of a case-control study of invasive cervical carcinoma in Brazil in which cervical specimens were examined for HPV DNA and serum specimens were tested for antibodies to HPV-16 E6 and E7 proteins (8) . In the present study, we have tested the case and control sera for antibodies to HPV-16 VLPs to relate this serological response to case or control status, HPV type in the cervix, presence of antibodies to E6 and E7 proteins, disease stage, and risk factors for sexually transmitted infections. We also evaluated HPV serology as a screening test for cervical cancer, which could be used in situations in which more sophisticated technology is impractical and cervical specimens are not available.

	Materials and Methods

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Study Subjects.
Serum collection and study design were described in detail in previous reports (8 , 9) . Briefly, cases were women, age 25–79 years, in Sao Paulo City, with newly diagnosed and histopathologically confirmed invasive cervical cancer and with no previous treatment for the disease. Cases were categorized in clinical stages following the Federation Internationale des Gynaecologistes et Obstetristes classification scheme as stage I (n = 42), stage II (n = 64), and stage III-IV (n = 70). For 18 cases, there was no information on stage of disease. Controls were women recruited from the same hospitals as the cases and were frequency matched to cases in 5-year age groups. Those who were admitted for treatment of a gynecological condition or who had a hysterectomy or conization were ineligible as controls. HPV diagnosis was performed by PCR on samples of exfoliated cells from the ecto- and endocervix collected on gynecological examination, using a combination of general and type-specific primers (10) .

Serum specimens were collected at the time of the gynecological examination, stored at -20°C, and available for 194 of 199 cases and 217 of 225 controls for this study.

VLP Production and Purification.
The baculovirus construct containing the L1 and L2 genes of HPV-16 was kindly provided by J. Schiller (National Cancer Institute, Bethesda, MD). Sf9 insect cells were grown in a spinner flask to a density of 2° 10⁶/ml at 27°C in 500 ml of Grace’s insect media (Invitrogen, San Diego, CA) with 10% fetal bovine serum, containing gentamicin and Fungizone of recommended concentrations. The cells from a 1-liter culture were infected with recombinant baculoviruses at a multiplicity of infection of 10 determined by plaque assay. After 1 h of incubation at room temperature, the cells were transferred to a total of 20 square tissue culture plates (245 x 245 mm; Nunc, Naperville, IL) containing 100 ml of Grace’s complete media with antibiotics in each plate. The infected cells were allowed to grow for 72 h at 27°C in a high-humidity incubator and harvested by gentle scraping with a pipette and pelleted by centrifugation. The VLPs were purified as described by Kirnbauer et al. (1) . Successful preparation of VLP was confirmed by electron microscopic examination as well as SDS-PAGE.

ELISA.
Sera were tested by ELISA for antibodies against HPV-16 VLP as described (6) . Briefly, wells of microtiter plates (Corning, Acton, MA) were coated with 50 µl of purified VLP at a concentration of 5 µg/ml in PBS (pH 7.4) and held overnight at 4°C. Fifty microliters of test sera diluted 1:10 in PBS containing 0.5% nonfat milk were added to each of two wells and incubated for 1 h at 37°C. Specific antibodies were detected with horseradish peroxidase-conjugated recombinant protein G (Zymed Laboratories, San Francisco, CA) diluted 1:10,000 in PBS and 0.05% Tween-20 after 30 min of incubation with freshly prepared 2,2'-azinobis(3-ethylbenzthiazoline sulfonic acid) and hydrogen peroxide solution (Kirkegaard and Perry, Gaithersburg, MD).

Seroreactivity was recorded as absorbance using a microtiter plate reader (Molecular Devices, Menlo Park, CA). The cutoff absorbance for seropositivity was determined by reference to previously tested negative control serum samples obtained from children and college age women at low risk for HPV infection (6) . Sera with A > 0.183 were scored positive.

Detection of Antibodies to HPV 16 E6 and E7 Proteins.
Antibodies were detected by radioimmunoprecipitation of full-length HPV 16 E6 and E7 proteins prepared by in vitro transcription and translation as described previously (8) .

Statistical Analysis.
The distributions of absorbance values were compared for cases and controls by Mann-Whitney U test (Kruskal-Wallis test for more than two groups). Frequencies were compared by ² test or Fisher’s exact test (two-tailed). ORs and 95% confidence limits were calculated as approximations of relative risks using unconditional logistic regression analysis. Relationship between VLP and E6 and E7 antibody reactions among cases and controls were analyzed by Spearman’s correlation.

	Results

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Antibodies to HPV-16 VLP in Cases and Controls.
The distribution of A values in cases and controls is shown in Fig. 1 . The median A values (and interquartile range) for cases and controls were 0.165 (range, 0.099–0.356) and 0.118 (range, 0.080–0.182), respectively. The difference between the two distributions was significant by Mann-Whitney test (P < 0.001). Fig. 1 also showed that A values of 0.400 and above were found most frequently among cases; 46 of 194 (23.7%) case sera, and 13 of 217 (6%) control sera were strongly positive (P < 0.001). A values >0.776 were found exclusively in case sera, in 27 specimens. The cases and controls were also compared for the proportions of sera that were antibody positive (47.4 versus 24.4%; ² test, P < 0.001; OR, 2.8; 95% CI, 1.8–4.3). HPV-16 seropositivity was associated with cervical cancer even after controlling for HPV-16 DNA status (OR, 2.3; 95% CI, 1.3–4.2).

View larger version (18K): [in this window] [in a new window]   Fig. 1. Seroreactivity in HPV-16 VLP ELISA of 194 cervical cancer cases and 217 controls. The length of each box corresponds to the interquartile range, with the top boundary of the box representing the 75th and the bottom boundary the 25th percentile. The horizontal line in the box indicates the median value. The small bar at the end of the line extending upward from the box plot shows the 90th percentile. Outlier values are shown as open circles. The solid horizontal line extending across the graph marks the cutoff for positivity, and the dotted horizontal line marks the cutoff for strongly positive sera. When the sensitivity and specificity were calculated using various cutoff A values, similar ORs were obtained for case-control comparisons (0.183 A units [chosen cut point], OR, 2.8; 0.200 A units, OR, 2.5; 0.250 A units, OR, 2.4; 0.300 A units, OR, 2.8; and 0.350 A units, OR, 3.5).

View larger version (14K): [in this window] [in a new window]   Fig. 2. Seroreactivity in HPV-16 VLP ELISA of cervical cancer cases (A) and controls (B) by HPV DNA diagnosis. See legend to Fig. 1 for explanation of box plot diagrams.

VLP Antibody Response in Women with Selected Risk Factors for Cervical Cancer.
Cases and controls were examined for the relationship of VLP antibody prevalence and selected risk factors for cervical cancer (Table 2) . In both groups, antibody prevalence increased with increasing number of lifetime sexual partners (² for trend, P < 0.001). Age at first intercourse was not related to HPV-16 seropositivity among cases, but a nonsignificant inverse trend was observed among controls. Antibody prevalence was not significantly different in different age groups of cases. Among the controls, age was significantly inversely associated with HPV-16 seropositivity (² for trend, P = 0.019). There was no association between HPV-16 VLP seropositivity and stage of disease or histological diagnosis (data not shown).

HPV Serology as a Screening Test for Cervical Cancer.
The serological assays were also evaluated as screening tests for invasive cervical cancer (Table 4) . HPV-16 VLP serology had a sensitivity of 47.4% and a specificity of 75.6%, whereas HPV-16 E6 and E7 serology had a sensitivity of 63.4% and a specificity of 89.9%. If reactivity to any HPV-16 protein was considered indicative of the presence of cervical cancer, serology detected 80.2% of cases, but the specificity of the combined assays was low (68.7%). By adjusting the cutoff in each assay, it was possible to achieve a sensitivity of 53.6% and a specificity of 93.6% for high titers to at least one of the three antigens.

	Discussion

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The OR of 2.8 for the association of antibodies to HPV-16 VLPs and cervical cancer was less than that for antibodies to E6 (OR, 18.5) or E7 (OR, 9.1). The weaker association observed for antibody responses to VLPs can be accounted for largely by the higher seroprevalence to VLPs compared with E6 and E7 proteins, among controls. An antibody response to VLPs among controls is consistent with numerous studies showing that VLP antibodies are markers of HPV infection (4, 5, 6 , 16, 17, 18, 19, 20, 21, 22, 23) . Among cases, irrespective of their HPV DNA status, there was no correlation between seroreactivity to HPV-16 VLPs and HPV-16 oncoproteins. The reason for this is not clear, but it may reflect differences in the processes responsible for antibody responses to VLPs and to oncoproteins. E6 and E7 antibodies are known to be associated almost exclusively with invasive cervical cancer and to correlate with tumor burden. In contrast, antibodies to VLPs appear after infection and are probably related to the duration of vegetative DNA replication and expression of capsid proteins. Because the two processes are temporally disparate, it is not surprising that the antibody responses they induce are not correlated. A longitudinal study would be required to address the temporal relationship between antibody responses to different HPV proteins and stage of HPV infection.

The analysis of HPV-16 VLP antibodies in relation to risk factors for cervical cancer showed that seroprevalence markedly increased with an increasing number of lifetime sexual partners. Among controls, seroprevalence increased from 16% in subjects with one partner to 58% in those with more than four partners, and among cases, it increased from 34% in subjects with one partner to 73% in subjects with four or more partners. This pattern has been a consistent finding in epidemiological studies using VLP-based ELISA and would be expected for a sexually transmitted infectious agent (6 , 16 , 20 , 23) . The trend was seen in cases irrespective of the presence or absence of HPV-16 infection detected by PCR (data not shown). This observation implies that multiple sex partners and, consequently, the opportunity for multiple exposures to HPV-16 is a determinant of HPV-16 VLP seroreactivity independent of a persistent HPV-16 infection. A possible explanation for this is that repeated exposure to HPV-16 capsid proteins after a transient infection with HPV-16 further stimulates antibody production.

The use of molecular diagnostic techniques, particularly HPV DNA assays, in cervical cancer screening programs is currently under active consideration. Assays for HPV DNA are attractive screening tests because most, if not all, cervical cancers contain HPV genomes. Because HPV infections occur primarily in young, sexually active women, the specificity of PCR in older women at risk for cervical cancer is high. We compared three serological assays as screening tests for invasive cervical cancer. Nearly half of the cervical cancer cases were detected by HPV-16 VLP serology (47.4%), and almost two-thirds were detected by HPV-16 E6 and E7 serology (63.4%). The specificity of HPV 16 VLP serology was poor for a screening test (75.6%), and that of HPV-16 E6 and E7 serology was fair (89.9%). The optimal performance of serological assays was achieved by a combination of high titers of antibody to any of the three proteins (sensitivity, 53.6%; specificity, 93.6%). One caveat to the use of E6 and E7 serology for screening is that E6 and E7 antibodies are markers of invasive cervical cancer but not of high-grade squamous intraepithelial lesions (24) . Therefore, serological testing for E6 and E7 antibodies would not identify women with preinvasive disease. Although the HPV-16 VLP ELISA had a sensitivity of only 50%, testing for reactivity to VLPs of other oncogenic types would most likely increase the sensitivity of VLP serology. However, the specificity of VLP serology would be low, resulting in many false-positive results if the test were used for cancer screening. An effective and commonly used strategy in this situation is to combine a sensitive screening test with a highly specific confirmatory test. This strategy has been used successfully for HIV diagnosis by using ELISA for screening and Western blot for confirmation (25) . VLP serology could, for example, be combined with a confirmatory PCR. Given the limited value of cytology in underdeveloped countries and the difficulties in obtaining cervical smears, it is worthwhile to consider the value of serological assays in cervical cancer screening programs in these regions.

	Footnotes

 
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ Supported by NIH Grant AI42058.

² To whom requests for reprints should be addressed, at The Johns Hopkins Hospital, Blalock Building, Room 1111, 600 North Wolfe Street, Baltimore, MD 21287. E-mail: rviscidi{at}welchlink.welch.jhu.edu

³ The abbreviations used are: HPV, human papillomavirus; VLP, virus-like particle; OR, odds ratio; CI, confidence interval.

Received 3/ 2/99; revised 7/21/99; accepted 7/28/99.

	References

Top Abstract Introduction Materials and Methods Results Discussion References

 

1. Kirnbauer R., Taub J., Greenstone H., Roden R., Durst M., Gissmann L., Lowy D. R., Schiller J. T. Efficient self-assembly of human papillomavirus type 16 L1 and L1–L2 into virus-like particles. J. Virol., 67: 6929-6936, 1993.[Abstract/Free Full Text]
2. Zhou J., Sun X. Y., Stenzel D. J., Frazer I. H. Expression of vaccinia recombinant HPV 16 L1 and L2 ORF proteins in epithelial cells is sufficient for assembly of HPV virion-like particles. Virology, 185: 251-257, 1991.[Medline]
3. Rose R. C., Bonnez W., Reichman R. C., Garcea R. L. Expression of human papillomavirus type 11 L1 protein in insect cells: in vivo and in vitro assembly of viruslike particles. J. Virol., 67: 1936-1944, 1993.[Abstract/Free Full Text]
4. Kirnbauer R., Hubbert N. L., Wheeler C. M., Becker T. M., Lowy D. R., Schiller J. T. A virus-like particle enzyme-linked immunosorbent assay detects serum antibodies in a majority of women infected with human papillomavirus type 16. J. Natl. Cancer Inst., 86: 494-499, 1994.[Abstract/Free Full Text]
5. Carter J. J., Koutsky L. A., Wipf G. C., Christensen N. D., Lee S. K., Kuypers J., Kiviat N., Galloway D. A. The natural history of human papillomavirus type 16 capsid antibodies among a cohort of university women. J. Infect. Dis., 174: 927-936, 1996.[Medline]
6. Viscidi R. P., Kotloff K. L., Clayman B., Russ K., Shapiro S., Shah K. V. Prevalence of antibodies to human papillomavirus (HPV) type 16 virus-like particles in relation to cervical HPV infection among college women. Clin. Diagn. Lab. Immunol., 4: 122-126, 1997.[Abstract]
7. Wideroff L., Schiffman M. H., Nonnenmacher B., Hubbert N., Kirnbauer R., Greer C. E., Lowy D., Lorincz A. T., Manos M. M., Glass A. G., Scott D. R., Sherman M. E., Buckland J., Lowy D., Schiller J. Evaluation of seroreactivity to human papillomavirus type 16 virus-like particles in an incident case-control study of cervical neoplasia. J. Infect. Dis., 172: 1425-1430, 1995.[Medline]
8. Sun Y., Eluf-Neto J., Bosch F. X., Munoz N., Booth M., Walboomers J. M., Shah K. V., Viscidi R. P. Human papillomavirus-related serological markers of invasive cervical carcinoma in Brazil. Cancer Epidemiol., Biomarkers & Prev., 3: 341-347, 1994.[Abstract]
9. Eluf-Neto J., Booth M., Munoz N., Bosch F. X., Meijer C. J., Walboomers J. M. Human papillomavirus and invasive cervical cancer in Brazil. Br. J. Cancer, 69: 114-119, 1994.[Medline]
10. van den Brule A. J., Meijer C. J., Bakels V., Kenemans P., Walboomers J. M. Rapid detection of human papillomavirus in cervical scrapes by combined general primer-mediated and type-specific polymerase chain reaction. J. Clin. Microbiol., 28: 2739-2743, 1990.[Abstract/Free Full Text]
11. Nonnenmacher B., Hubbert N. L., Kirnbauer R., Shah K. V., Munoz N., Bosch F. X., de Sanjose S., Viscidi R., Lowy D. R., Schiller J. T. Serologic response to human papillomavirus type 16 (HPV-16) virus-like particles in HPV-16 DNA-positive invasive cervical cancer and cervical intraepithelial neoplasia grade III patients and controls from Colombia and Spain. J. Infect. Dis., 172: 19-24, 1995.[Medline]
12. Luxton J. C., Rose R. C., Coletart T., Wilson P., Shepherd P. S. Serological and T-helper cell responses to human papillomavirus type 16 L1 in women with cervical dysplasia or cervical carcinoma and in healthy controls. J. Gen. Virol., 78: 917-923, 1997.[Abstract]
13. Sasagawa T., Inoue M., Lehtinen M., Zhang W., Gschmeissner S. E., Hajibagheri M. A., Finch J., Crawford L. Serological responses to human papillomavirus type 6 and 16 virus-like particles in patients with cervical neoplastic lesions. Clin. Diagn. Lab. Immunol., 3: 403-410, 1996.[Abstract]
14. Park J. S., Park D. C., Kim C. J., Ahn H. K., Um S. J., Park S. N., Kim S. J., Namkoong S. E. HPV-16-related proteins as the serologic markers in cervical neoplasia. Gynecol. Oncol., 69: 47-55, 1998.[Medline]
15. Rose R. C., Bonnez W., Da Rin C., McCance D. J., Reichman R. C. Serological differentiation of human papillomavirus types 11, 16 and 18 using recombinant virus-like particles. J. Gen. Virol., 75: 2445-2449, 1994.[Abstract/Free Full Text]
16. Dillner J., Kallings I., Brihmer C., Sikstrom B., Koskela P., Lehtinen M., Schiller J. T., Sapp M., Mardh P. A. Seropositivities to human papillomavirus types 16, 18, or 33 capsids and to Chlamydia trachomatis are markers of sexual behavior. J. Infect. Dis., 173: 1394-1398, 1996.[Medline]
17. Wikstrom A., Van Doornum G. J., Kirnbauer R., Quint W. G., Dillner J. Prospective study on the development of antibodies against human papillomavirus type 6 among patients with condyloma acuminata or new asymptomatic infection. J. Med. Virol., 46: 368-374, 1995.[Medline]
18. Wikstrom A., Van Doornum G. J., Quint W. G., Schiller J. T., Dillner J. Identification of human papillomavirus seroconversions. J. Gen. Virol., 76: 529-539, 1995.[Abstract/Free Full Text]
19. Eisemann C., Fisher S. G., Gross G., Muller M., Gissmann L. Antibodies to human papillomavirus type 11 virus-like particles in sera of patients with genital warts and in control groups. J. Gen. Virol., 77: 1799-1803, 1996.[Abstract/Free Full Text]
20. Carter J. J., Wipf G. C., Hagensee M. E., McKnight B., Habel L. A., Lee S. K., Kuypers J., Kiviat N., Daling J. R., Koutsky L. A., Watts D. H., Holmes K. K., Galloway D. A. Use of human papillomavirus type 6 capsids to detect antibodies in people with genital warts. J. Infect. Dis., 172: 11-18, 1995.[Medline]
21. Heim K., Christensen N. D., Hoepfl R., Wartusch B., Pinzger G., Zeimet A., Baumgartner P., Kreider J. W., Dapunt O. Serum IgG, IgM, and IgA reactivity to human papillomavirus types 11 and 6 virus-like particles in different gynecologic patient groups. J. Infect. Dis., 172: 395-402, 1995.[Medline]
22. Svare E. I., Kjaer S. K., Nonnenmacher B., Worm A. M., Moi H., Christensen R. B., van den Brule A. J., Walboomers J. M., Meijer C. J., Hubbert N. L., Lowy D. R., Schiller J. T. Seroreactivity to human papillomavirus type 16 virus-like particles is lower in high-risk men than in high-risk women. J. Infect. Dis., 176: 876-883, 1997.[Medline]
23. Wideroff L., Schiffman M. H., Hoover R., Tarone R. E., Nonnenmacher B., Hubbert N., Kirnbauer R., Greer C. E., Lorincz A. T., Manos M. M., Glass A. G., Scott D. R., Sherman M. E., Buckland J., Lowy D., Schiller J. Epidemiologic determinants of seroreactivity to human papillomavirus (HPV) type 16 virus-like particles in cervical HPV-16 DNA-positive and-negative women. J. Infect. Dis., 174: 937-943, 1996.[Medline]
24. Viscidi R. P., Sun Y., Tsuzaki B., Bosch F. X., Munoz N., Shah K. V. Serologic response in human papillomavirus-associated invasive cervical cancer. Int. J. Cancer, 55: 780-784, 1993.[Medline]
25. Coutlee F., Viscidi R. P., Yolken R. Assays for the diagnosis of HIV infections Broder S. Merigan T. C. Bolognesi D. eds. . Textbook of AIDS Medicine, : 651-663, Williams & Wilkens Baltimore 1994.

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