Immunological methods have been used to detect an oncoprotein associated with human papillomaviruses (HPV) that cause cervical cancer.
Immunological detection of the E7 oncoprotein is an attractive alternative for triage of suspicious and borderline cytology to highlight and identify the often-rare dysplastic cells present in a cell scrape.
Scientists at the University of Gothenburg (Sweden) raised monoclonal antibodies against the E7 oncoprotein, which is an absolute prerequisite of malignant transformation and the protein is expressed at increasing levels during cancer development.
Antibodies specific for the E7 protein of oncogenic HPV types were selected using immunological methods such as enzyme-linked immunosorbent assay (ELISA), Western blot, immunocytochemistry and flow cytometry. Phage display was used to identify antibody epitopes thereby predicting and verifying antibody specificity.
Two of the antibodies, recognizing HPV16 and HPV18 E7 demonstrated strong staining of dysplastic cells in HPV-positive specimens in immunocytochemistry and could have the potential to be used in a clinical setting. Since the antibodies detect the protein in Liquid-based cytology, which normally leaves residual sample after standard cytology, E7 testing can easily be performed without recalling the patient for additional sampling. About 250 women in Sweden still die every year due to cervical cancer, while another 500 develop the cancer, regardless of intensive screenings.
Maria Lidqvist, a doctoral student at the Sahlgrenska Academy (Gothenburg, Sweden) who presented this new technique in her thesis, said, “Around 70% of all cervical cancer cases are caused by two specific virus types, known as HPV16 and HPV18. We have developed a method that identifies proteins of these or oncogenic viruses in cells, enabling a more objective interpretation of the test results. Monoclonal antibodies against human papillomavirus E7 oncoprotein can be used for diagnosis of cervical neoplasia and cancer. This method can hopefully produce a more reliable diagnosis in uncertain cases and reduce the number of missed cancer cases, as well as the number of women who have to be recalled because of cell samples that are difficult to interpret.”