Identification of immunoreactive antigens of human papillomavirus type 6b by using Escherichia coli-expressed fusion proteins.

Human papillomavirus (HPVs) infect the genital epithelium and are found in proliferative lesions ranging from benign condylomata to invasive carcinomas. The immunological response to these infections is poorly understood because of the lack of purified viral antigens. In this study, bacterially derived fusion proteins expressing segments of all the major open reading frames (ORFs) of HPV type 6b (HPV-6b) have been used in Western blot (immunoblot) assays to detect antibodies directed against HPV-encoded proteins. The most striking reactivities present in sera from patients with genital warts were to the HPV-6b L1 ORF protein and, to a lesser extent, to the HPV-6b L2 ORF protein. Two cases of reactivity to HPV-6b E2 ORF were observed, but no reactivities were seen with other HPV-6b constructs. Two sera reacted with the HPV-16 L2 fusion protein, and two sera reacted with the HPV-16 E4 protein. The antibodies directed against the HPV-6b fusion proteins showed no cross-reactivity with comparable regions of the HPV-16 ORFs. This assay provides a useful approach for further studies of HPV serology.