title: Generation and neutralization of pseudovirions of human papillomavirus type 33.
abstract: Since human papillomaviruses (HPV) cannot be propagated in cell culture, the generation of infectious virions in vitro is a highly desirable goal. Here we report that pseudovirions can be generated by the assembly of virus-like particles (VLPs) in COS-7 cells containing multiple copies of a marker plasmid. Using recombinant vaccinia viruses, we have obtained spherical VLPs of HPV type 33 (HPV-33) which fractionate into heavy and light VLPs in cesium chloride density gradients. VLPs in the heavy fraction (1.31 g/cm3) carry the plasmid in DNase-resistant form and are capable of transferring the genetic marker located on the plasmid to COS-7 cells in a DNase-resistant way (pseudoinfection). The minor capsid protein L2 is not required for encapsidation but is essential for efficient pseudoinfection. Antiserum to HPV-33 VLPs inhibits VLP-mediated DNA transfer with high efficiency. Antisera to VLPs of HPV-18 and HPV-16 are not neutralizing, although the HPV-16 antiserum exhibited some cross-reactivity with HPV-33 VLPs in an enzyme-linked immunosorbent assay. In a cell binding assay, the titer of the HPV-33 VLP antiserum was 1:200 compared to the neutralization titer of 1:10(5). This indicates that neutralization is essentially due to the inhibition of cellular processes after VLP binding to cells. The encapsidation of marker plasmids into VLPs provides a sensitive and fast assay for the evaluation of neutralizing potentials of antisera against papillomavirus infections.
authors.affiliation: Institute for Medical Microbiology and Hygiene, University of Mainz, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Unckell
authors.forename: R E
authors.initials: RE
authors.lastname: Streeck
authors.forename: M
authors.initials: M
authors.lastname: Sapp
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D019556:COS Cells; D002213:Capsid / Q000235:genetics / Q000378:metabolism; D036022:Capsid Proteins; D004279:DNA, Viral / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D006801:Humans; D009500:Neutralization Tests; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism; D027383:Papillomaviridae / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D014771:Virion; D019065:Virus Assembly
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D004279:DNA, Viral; D009856:Oncogene Proteins, Viral; C080100:oncogene viral capsid protein L2, human papillomavirus type 33; D003850:Deoxyribonuclease I