Detection of E5 oncoprotein in human papillomavirus type 16-positive cervical scrapes using antibodies raised to synthetic peptides

Polyclonal antibodies were raised to partial and full-length synthetic peptides of human papillomavirus type 16 (HPV-16) E5. Antisera specificity for HPV-16 E5 was demonstrated by their ability to recognize not only their peptide immunogens but also full-length peptide and a glutathione S-transferase-E5 fusion protein. The most reactive antiserum, PE-6, raised to a full-length peptide, was used in Western blot analysis to identify HPV-16 E5 protein from exfoliated cervical cells. A strong, single band at approximately 20K was detected in two of six HPV-16-positive samples from women with a history of low-grade cervical intraepithelial neoplasia. The apparent M(r) by SDS-PAGE suggests that HPV-16 E5 forms homodimers in vivo, but not through cysteine linkage.