Comparison of the Efficacies of Different ELISA formats in Sero-detection of Antibodies to HPV 16 E7 Oncoprotein

Different formats-the indirect ELISAs with either peptide or the E7 whole protein as antigens and the more recent GST-E7 capture ELISA have been employed in sero-epidemiological studies for the determination of HPV infection. Further, several studies have attempted to correlate seroprevalence with prognosis and/or early diagnosis of cancer. This study compares the efficacy of ELISA in sero-detection when different forms of the E7 antigen viz., E7 peptides, E7 wholeantigen, and GST-E7 fusion protein are used. The sera samples collected from hospital-visiting women were grouped into two categories“suspect” negative (n=20; from women 18 years of age and negative for HPV 16 L1 antibodies determined by the VLP ELISA) and “suspect” positive (n=40; from women whose corresponding Pap smear samples showed presence of HPV 16 DNA and serum showed sero-positivity for HPV 16 L1 antibodies). The suspect negative sera showed absorbance readings below the respective cut-off points in all formats of the ELISA. However the suspect positive samples showed varied results with ∼4%, ∼20% and ∼73% of samples showing absorbance readings above the cut-off in the E7 Peptide, E7 whole-antigen and GST-E7 capture ELISAs respectively. The results indicate that the GST-E7 based capture ELISA might be best suited for use in the sero-detection of antibodies in individuals with unknown disease or infection status.