Papillomaviruses replicate in stratified epithelia of skin and mucosa. Infection with certain human papillomavirus (HPV) types is the main cause of anogenital neoplasia, in particular cervical cancer. Early events of papillomavirus infectivity are poorly understood. While heparan sulfate proteoglycans (HSPGs) mediate initial binding to the cell surface, the class of proteins carrying heparan sulfates has not been defined. Here we examined two processes of papillomavirus infection, attachment of virus-like particles (VLP) to cells and infection with authentic HPV type 11 (HPV11) virions. Of the HSPGs, syndecan-1 is the major epithelial form and is strongly upregulated in wound edge keratinocytes. We employed K562 cells, which lack HSPGs except minor amounts of endogenous betaglycan, and stable clones that express cDNAs of syndecan-1, syndecan-4, or glypican-1. Binding of VLP correlated with levels of heparan sulfate on the cell surface. Parental K562 bound HPV16 VLP weakly, whereas all three K562 transfectants demonstrated enhanced binding, with the highest binding capacity observed for syndecan-1-transfected cells, which also expressed the most HSPG. For HPV11 infectivity assays, a high virion inoculum was required to infect K562 cells, whereas ectopic expression of syndecan-1 increased permissiveness eightfold and expression of syndecan-4 or glypican-1 fourfold. Infection of keratinocytes was eliminated by treatment with heparitinase, but not phospholipase C, further implicating the syndecan family of integral membrane proteins as receptor proteins. Human keratinocytes with a homozygous deletion of ␣6 integrin are permissive for HPV11 infection. These results indicate that several HSPGs can serve as HPV receptors and support a putative role for syndecan-1, rather than ␣6 integrin, as a primary receptor protein in natural HPV infection of keratinocytes.Papillomaviruses comprise a large group of species-and tissue-specific DNA tumor viruses found in higher vertebrates from chaffinches to humans and include more than 90 known human papillomavirus (HPV) genotypes. Papillomaviruses cause mainly benign epithelial papillomas or warts on skin and mucosa (condylomata acuminata). Several high-risk HPV types, most often HPV type 16 (HPV16), are the primary etiologic agents for anogenital malignancy, in particular cervical cancer, which is the second most common cause of cancerrelated deaths in women worldwide (41, 57). The papillomavirus virion consists of a nonenveloped capsid comprised of the L1 major and L2 minor structural proteins surrounding a minichromosome of ϳ8 kb of double-stranded closed circular and histone-associated DNA. Even in the absence of other viral proteins, the L1 protein self-assembles into empty capsids or virus-like particles (VLP) (24). Subunit vaccines based on VLP have been developed, and prophylactic immunizations have demonstrated safety and efficacy in preventing papillomavirus infection and associated neoplasia (18,23,25,28,44).Papillomaviruses do not complete their life cycle leading to pr...

Genomes of human papillomaviruses (HPV) are common in biopsies from non-melanoma skin cancers but are also found on healthy skin and it is possible that HPV positivity in tumor biopsies by PCR may merely reflect contamination of the lesion surface. To investigate this issue, 229 immunocompetent patients were tested for HPV DNA in swab samples collected on top of skin tumors and in biopsies of the same tumors, obtained after stripping with tape to remove superficial layers. HPV DNA was detected on top of 69% (159 of 229) of the lesions, and in 12% (28 of 229) of the stripped biopsies (p<0.001). The difference was seen for all four types of tumors studied. Seborrheic keratosis had 79% (34 of 43) HPV positivity on top of lesions versus 19% (eight of 43) in biopsies; actinic keratosis had 83% (38 of 46) HPV positivity on top versus 11% (five of 46) in biopsies; basal cell carcinoma had 63% (69 of 109) on top versus 8% (nine of 109) in biopsies and squamous cell carcinoma had 58% (18 of 31) on top versus 19% (six of 31) in biopsies. HPV DNA is common in superficial layers of lesions, but is not necessarily present throughout tumors.

Cutaneous human papillomaviruses (HPV) are common in nonmelanoma skin cancers, benign skin lesions, and healthy skin. Increased seroprevalences for cutaneous HPV among nonmelanoma skin cancer patients have been described. To determine whether antibodies to cutaneous HPV are related to presence of the virus and/or to skin disease, we collected serum and biopsies from both lesions and healthy skin from 434 nonimmunosuppressed patients (72 squamous cell carcinomas, 160 basal cell carcinomas, 81 actinic keratoses, and 121 benign lesions). Biopsies were analyzed for HPV DNA by PCR, cloning, and sequencing. Serum antibodies to the major capsid protein L1 of HPV 1,5,6,8,9,10,15,16,20,24,32,36,38, and 57 as well as to the oncoproteins E6 and E7 of HPV 8 and 38 were detected using a multiplexed fluorescent beadbased assay. Type-specific seroprevalence among patients with the same type of HPV DNA (sensitivity of serology) varied from 0% to at most 28%. Presence of HPV DNA and antibodies to the same HPV type was not significantly correlated. However, seropositivity to any HPV type was significantly more common among patients positive for HPV DNA of any HPV type (odds ratio, 1.90; 95% confidence interval, 1.55-2.34). Seroprevalences were similar among the different patient groups but was, for most HPV types, somewhat higher among squamous cell carcinoma patients than among basal cell carcinoma patients (P < 0.01). In conclusion, additional studies are required to clarify the biological meaning of seropositivity as a marker of cutaneous HPV infection and skin disease. (Cancer Epidemiol Biomarkers Prev 2008;17(1):189 -95)

Peptides of the papillomavirus L2 minor capsid protein can induce antibodies (Ab) that neutralize a broad range of human papillomavirus (HPV) genotypes. Unfortunately, L2 is antigenically subdominant to L1 in the virus capsid. To induce a strong anti-L2 Ab response with cross-neutralizing activity to other mucosal types, chimeric virus-like particles (VLP) were generated in which HPV16 L2 neutralization epitopes (comprising L2 residues 69-81 or 108-120) are inserted within an immunodominant surface loop (between residues 133 and 134) of the L1 major capsid protein of bovine papillomavirus type 1 (BPV1). These chimeras self-assembled into pentameric capsomers, or complete VLP similar to wild type (wt) L1 protein. Immunization of rabbits with assembled particle preparations induced L2-specific serum Ab with titers 10-fold higher than those induced by cognate synthetic L2 peptides coupled to KLH. Antisera to both chimeric proteins partially neutralized HPV16 pseudovirions, confirming that both HPV16 L2 peptides define neutralization epitopes. When analyzed for the ability to cross-neutralize infection by authentic HPV11 virions, using detection of early viral RNA by RT-PCR-assays as the readout, immune serum to chimeric protein comprising L2 residues 69-81, but not 108-120, was partially neutralizing. In addition, mouse-antiserum induced by vaccinations with synthetic L2 peptide 108-120, but not 69-81, was partially neutralizing in this assay. Induction of cross-neutralization Ab by L2 epitopes displayed on chimeric VLP represents a possible strategy for the generation of broad-spectrum vaccines to protect against relevant mucosal HPV and associated neoplasia.

Neutralization capsid epitopes are important determinants for antibody-mediated immune protection against papillomavirus (PV) infection and induced disease. Chimeric L1 major capsid proteins of the human PV type 16 (HPV-16) and the bovine PV type 1 (BPV-1) with a foreign peptide incorporated into several capsid surface loops self-assembled into pentamers or virus-like particles (VLP). Binding patterns of neutralizing monoclonal antibodies (MAb) and immunization of mice confirmed (i) that regions around aa 282-286 and 351-355 contribute to neutralization epitopes and identified the latter region as an immunodominant site and (ii) that placing a foreign peptide in the context of an assembled structure markedly enhanced its immunogenicity. Pentamers disassembled from wild-type HPV-16 and BPV-1 VLPs displayed some of the neutralization epitopes that were detected on fully assembled VLPs, but were deficient for binding a subset of neutralizing MAb that inhibit cell attachment.Papillomavirus (PV) infections are widespread in animals and humans, causing mostly benign epithelial proliferations, papillomas or warts, of the skin and mucous membranes (Howley, 1991 ;Lowy et al., 1994 ; zur Hausen, 1991). Infection with oncogenic types, most often human PV type 16 (HPV-16), has been aetiologically associated with the development of anogenital malignancies, in particular cervical cancer (zur Hausen, 1994). PVs are nonenveloped " 8 kb double-stranded DNA viruses with a T l 7 icosahedral symmetry and a