Elevated Titer and Seropositivity of the Antibody to Human Papillomavirus E6 Protein in Cervical Cancer Patients

Abstract

Development of cervical cancer is associated with human papillomavirus (HPV) infection. However, data on comparison among the antibodies of anti-E6, anti-E7, and anti-L1 in the sera of patients with cervical cancer or HPV infection are very limited. In this study, we examined the expression of HPV-18 nonstructural proteins E6, E7, and the major capsid L1 protein in tissues from 25 patients with cervical cancer at stages ranging from Ib to IIa, based on the FIGO staging system. We also used ELISA to assess the antibodies against the HPV-18 E6, E7, and L1 proteins in the sera of these patients (patients) and in the sera of 20 healthy individuals (normal). Western blotting and immunohistochemical staining of these tissues confirmed the presence of the E6, E7, and L1 proteins. As compared to the normal controls, the patients' sera showed higher binding of the anti-E6, anti-E7, and anti-L1 antibodies. The anti-E6 and anti-E7 antibodies showed stronger binding than anti-L1 among all the 25 sera samples tested. The seropositive percentage of anti-E6 (88%) was higher than that of anti-E7 (32%) and anti-L1 (48%). These data suggest that elevated titer and seropositivity of the antibody to human papillomavirus E6 protein in the sera of cervical cancer patients. Interestingly, we also found that the 19 patients who indicated as anti-E6 seropositivity had a lower 5-year cumulate survival outcome.