Multiple conformational epitopes are recognized by natural and induced immunity to the E7 protein of human papilloma virus type 16 in man

The reactivity of sera from patients with cervical cancer with the E7 prote in of human papilloma virus type 16 (HPV16) was estimated using a novel non -radioactive immunoprecipitation assay and four established protein-and pep tide-based immunoassays. Six of 14 sera from patients with cervical cancer and 1 of 10 sera from healthy laboratory staff showed repeated reactivity w ith E7 in at least one assay. Four of the 7 reactive sera were consistently reactive in more than one assay, but only one was reactive in all four ass ays. Following immunization with E7, 2 of 5 patients with cervical cancer h ad increased E7-specific reactivity, measurable in one or more assays. No s ingle assay was particularly sensitive for E7 reactivity, or predictive of cervical cancer. Mapping of E7 reactivity to specific E7 peptides was unsuc cessful, suggesting that natural or induced E7 reactivity in human serum is commonly directed to conformational epitopes of E7, These results suggest that each assay employed with is study measures a different aspect of E7 re activity, and that various reactivities to E7 may manifest following HPV in fection or immunization. This finding is of significance for monitoring of E7 immunotherapy and for serological screening for cervical cancer. Copyrig ht (C) 2000 S.Karger, AG. Basel.