Expression of the full-length products of the human papillomavirus type 6b (HPV-6b) and HPV-11 L2 open reading frames by recombinant baculovirus, and antigenic comparisons with HPV-11 whole virus particles.

The L2 open reading frames (ORFs) of human papillomavirus (HPV) types 6b and 11 were expressed as full-length non-fusion proteins in Spodoptera frugiperda (Sf-9) cells using recombinant baculovirus. Both proteins were detected on Western blots as immunoreactive bands which migrated with apparent Mrs of 76K and 78K, respectively, and contained both cross-reactive and type-specific epitopes, as determined by polyclonal antisera directed against defined subregions of the HPV-6b and HPV-11 L2 ORFs. In addition, the minor capsid protein of HPV-11 particles co-migrates with the HPV-11 L2 ORF product and is immunoreactive with HPV-11 L2-specific antisera. These observations indicate that the anomalous electrophoretic mobilities of papillomavirus L2 ORF proteins can be explained without invoking post-transcriptional processing events and that the minor capsid protein of HPV-11 is antigenically and biophysically related to the HPV-11 L2 ORF product.