An ELISA capture assay for the E7 transforming proteins of HPV16 and HPV18

ELISA capture assays were established for the E7 transforming proteins of HPV16 and HPV18, based on a range of previously characterised polyclonal and monoclonal antibodies. No cross-reactivity was observed in the ELISAs between HPV18 E7 and HPV16 E7. Immunoreactive E7 protein (iE7) was measured in a series of HPV-transformed cell lines, and ranged from 0.6 to 17.7 ng iE7/mg cell protein. iE7 was labile at 22 degrees C (t1/2 = 37 min) but relatively more stable at 4 degrees C (t1/2 = 210 min). HPV16 E7 protein at concentrations from 0.10 to 0.69 ng iE7/mg cell protein was detected in 5 of 13 smears from women with abnormal cervical cytology. Assay of E7 protein may play a role in the detection of HPV-induced cervical lesions with malignant potential.