Recombinant Antigens E6 and E7 of Human Papilloma Virus Type 16: Preparation, Purification, and Assessment of the Immunogenicity and Antitumor Effects In Vivo

The recombinant proteins E6-CBD and E7-CBD, which are antigens E6 and E7 of human papillomavirus type 16 (HPV16), were connected by a glycine-serine spacer with the cellulose-binding domain (CBD) of Anaerocellum thermophilum in preparations obtained via synthesis in a heterologous expression system in Escherichia coli . A simple, effective, one-step technology for the isolation and purification of recombinant proteins E6-CBD and E7-CBD has been developed. The presence of antigenic properties in the obtained protein preparations was confirmed via Western blot. Three variants of immunogenic compositions with the recombinant proteins E6-CBD and E7-CBD and a three-dose immunization scheme have been developed. The immunogenicity was assessed in the BALB/c mice, and the antitumor effect of immunogenic compositions was studied on an experimental model of BALB/c mice with HPV16-associated tumors. It is shown that E6-CBD and E7-CBD are highly immunogenic and have antitumor effects in vivo. Both proteins, E6-CBD and E7-CBD, must be present to achieve the highest efficiency as part of the immunogenic composition. The obtained HPV16 recombinant antigens E6-CBD and E7-CBD can be used in two ways: ( a ) in clinical practice as the main specific components of therapeutic vaccines for the treatment of HPV16-associated neoplastic lesions of various localizations (cervical cancer, carcinoma of the anogenital tract, oropharynx) and ( b ) in diagnostics for the development of diagnostic kits to detect antibodies to E6 and E7 oncoproteins in patients with HPV16-associated malignant neoplasms.