Nine overlapping peptides (20 amino acid) covering the entire sequence of early antigen E7 of human papillomavirus type 16 (HPV-16) were synthesized and tested as antigens with human sera in ELISA. Five of these peptides (no. 1 to 5 counting from the N terminus of the E7 protein) reacted with a pool of sera from HPV-16-infected individuals (as determined by molecular hybridization with their biopsy specimens); one (no. 5) was also reactive with pools of HPV-18- and HPV-6- or 11-infected individuals. Sera from 24 patients with cervical intraepithelial neoplasia (CIN) and from 29 invasive cervical carcinoma (INCA) patients were tested for the presence of antibodies reactive with peptides, no. 1 to 4 covering amino acids 1 to 50 and with peptide no. 5 covering amino acids 41 to 60. Only one of the sera from CIN patients was reactive with peptides no. 1 (amino acids 1 to 20) and no. 4 (amino acids 31 to 50). However, the majority of these sera reacted with peptide no. 5. The occurrence of this antibody was only slightly less frequent in sera from healthy subjects compared to CIN patients. On the other hand, sera from the INCA patients were reactive with the peptides no. 1 to 3 more frequently than the sera from matched control subjects. Positive reactions of sera from INCA patients were most frequently seen with no. 2; 24% of these sera but only 7% of the controls were reactive with no. 2 peptide. The present data suggest that no. 1 to 3 are HPV-16-specific, whereas no. 5 is broadly cross-reactive.
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