title: A deletion and point mutation study of the human papillomavirus type 16 major capsid gene.
abstract: Recombinant human papillomavirus (HPV) virus-like particles (VLPs) made from the major capsid protein L1 are promising vaccine candidates for use as vaccines against genital and other HPV infections, and particularly against HPV-16. However, HPV-16 genotype variants have different binding affinities for neutralising mouse Mabs raised against HPV-16 L1 VLPs. This paper analyses, using a panel of well-characterised Mabs, the effects on the antigenicity of various C- and N-terminal deletants of HPV-16 L1 made in insect cells via recombinant baculovirus, of an A-->T mutation at residue 266 (A266T), and of a C-->G mutation at conserved position 428 (C428G). The effects of these changes on assembly of the variant L1s were studied by electron microscopy. Binding of Mab H16:E70 to A266T was reduced by almost half in comparison to wild type L1. Retention of the C-terminal region 428-483 was critical for the binding of conformation-specific Mabs (H16:V5, H16:E70, H16:U4 and H16:9A) whereas deletion of the nuclear localisation signal (NLS) or the C428G mutation or an N-terminal deletion (residues 2-9) did not affect the antigenicity. The N-terminal deletion resulted in a mixed population of 30 and 55nm VLPs, which differs from the same construct expressed in Escherichia coli, whereas pentamer aggregates resulted from deletion of the 428-465 region or the C428G mutation. The results have implications both for considering use of single-genotype HPV vaccines, and for design of novel second-generation vaccines.
authors.affiliation: Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Cape Town 7701, South Africa. arwind@science.uct.ac.za
authors.forename: Arvind
authors.initials: A
authors.lastname: Varsani
authors.forename: Anna-Lise
authors.initials: AL
authors.lastname: Williamson
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Jaffer
authors.forename: Edward P
authors.initials: EP
authors.lastname: Rybicki
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000914:Antibodies, Viral; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology; D036022:Capsid Proteins / Q000235:genetics* / Q000276:immunology*; D002460:Cell Line; D000939:Epitopes / Q000235:genetics / Q000276:immunology; D052162:Human papillomavirus 16 / Q000235:genetics* / Q000276:immunology*; D046529:Microscopy, Electron, Transmission; D017354:Point Mutation; D017384:Sequence Deletion; D018411:Spodoptera; D019065:Virus Assembly / Q000235:genetics
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D000939:Epitopes