Expression of human papilloma virus type 16 antigens, specific targeting as well as formation of virus-like particles by HSV-1 amplicon vectors

Abstract

Expression of human papilloma virus type 16 (HPV16) antigens by herpes simplex virus type 1 (HSV-1)-based amplicon vectors was investigated. Amplicons were packaged using HSV-1 LaL, a virus with a floxed 'a' sequence, and the CRE recombinase-expressing cell line TE-CRE30. In amplicon-infected BHK-21 cells, a 60-mer E7 peptide was weakly expressed, but its expression was significantly improved using a transcription unit with humanized codons. In contrast, the HPV16 structural proteins L1 and L2, as well as L1 fusion proteins with E7, were expressed at high levels. L1 displayed nuclear and cytoplasmic localization, and L1-E7 fusion proteins with a synthetic nuclear localization signal (NLS) from simian virus 40 (SV40) accumulated in the nuclei. The self-assembly of L1 into virus-like particles (VLPs) in HSV-1 amplicon-infected cells was confirmed by electron microscopy and a specific antigen-capture ELISA. For targeting of herpes virions with HPV16 antigens, a 60-mer E7 peptide was fused to the herpesviral tegument protein VP22 and envelope glycoprotein C (gC). Both fusion proteins, VP22E7 and gCE7, were demonstrated to be associated with sucrose gradient-purified infectious HSV-1 virion particles.