Particle-Mediated Gene Delivery and Human Skin: Ultrastructural Observations on Stratum Corneum Barrier Structures

The particle-mediated delivery systems are becoming a clinically relevant tool in dermatology and immunology. We investigated the qualitative ultrastructural morphology of skin following pressure-driven delivery of gold particles to ex vivo human breast skin, at different pressures ranging from 350 to 1,000 psi. Pressures of 800 and 1,000 psi appear to be more effective, as indicated by distribution of particles in the viable epidermis and dermis. Particle bombardment of the skin with gold beads caused microwounds that spanned the stratum corneum (SC). The SC lipids did not reseal these wounds in the SC after 24 h in organ culture. The implications of particle-mediated delivery to permeability barrier functions of the SC are discussed.

Optimization of cottontail rabbit papilloma virus challenge technique

Disease induced by Cottontail Rabbit Papilloma Virus (CRPV) scarification in domestic rabbits shares many attributes with disease induced by human papilloma virus (HPV). CRPV induces squamous papillomas in domestic rabbits, of which approximately 70% transform into invasive carcinomas. In advanced tumors, virus is often undetectable, and occasionally, some rabbits undergo spontaneous regression of papillomas. Techniques utilized to scarify rabbit skin are diverse, often labor intensive and time consuming with the possibility for significant variability. Using four unique infection techniques, resultant papilloma incidence, time to onset, and total papilloma volumes were compared to determine an optimal challenge method. Five rabbits were each infected with CRPV via a tattoo gun with and without ink, an intradermal injection, manual use of a tattoo needle, or a sterile blade followed by manual use of a tattoo needle. Papilloma formation was monitored weekly after inoculation for 6 weeks. CRPV papillomas began as pinpoint foci at 3 weeks post challenge and grew exponentially throughout the course of measurement. Individual foci coalesced rapidly to form larger papilloma aggregates. Although intradermal injection was well tolerated and easily performed, it was the worst method of papilloma production (2.2 mm(3) at 6 weeks). The best method, a sterile blade followed by manual use of a tattoo needle, produced significantly larger papillomas over all time periods (>1100 mm(3) at 6 weeks, P<0.01). Inoculation of CRPV using this method produces highly repeatable papillomas beginning 3 weeks post-infection.

High and low levels of cottontail rabbit papillomavirus E2 protein generate opposite effects on gene expression

The papillomavirus E2 protein plays an important role in viral transcriptional regulation and replication. We chose to study the cottontail rabbit papillomavirus (CRPV) E2 protein as a transcriptional regulator because of the availability of an animal model for papilloma formation, which may be relevant for human papillomavirus (HPV) infection and replication. We studied the effect of expression levels of E2 on the long control region, which contains transcriptional promoter and enhancer elements, and synthetic E2-dependent artificial promoters in which the E2 was the dominant factor in the transcriptional activation. These experiments indicated that high levels of E2 were inhibitory and low levels were stimulatory for transactivation. In addition, we showed that the complex formed between CRPV E2 and the cognate binding site was less stable than the complex formed between HPV E2 and the same cognate binding site. Furthermore, we showed that CRPV E2 binding to its transcriptional regulatory sequence was stabilized by other proteins such as E1, which produced increments in transcriptional activation of E2-dependent genes. The data may be used to define conditions in which the rabbit model can be used for the screening of drugs which are inhibitory to the HPV and CRPV replication and gene expression.

Granulocyte-macrophage colony-stimulating factor priming plus papillomavirus E6 DNA vaccination: effects on papilloma formation and regression in the cottontail rabbit papillomavirus--rabbit model

A cottontail rabbit papillomavirus (CRPV) E6 DNA vaccine that induces significant protection against CRPV challenge was used in a superior vaccination regimen in which the cutaneous sites of vaccination were primed with an expression vector encoding granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that induces differentiation and local recruitment of professional antigen-presenting cells. This treatment induced a massive influx of major histocompatibility complex class II-positive cells. In a vaccination-challenge experiment, rabbit groups were treated by E6 DNA vaccination, GM-CSF DNA inoculation, or a combination of both treatments. After two immunizations, rabbits were challenged with CRPV at low, moderate, and high stringencies and monitored for papilloma formation. As expected, all clinical outcomes were monotonically related to the stringency of the viral challenge. The results demonstrate that GM-CSF priming greatly augmented the effects of CRPV E6 vaccination. First, challenge sites in control rabbits (at the moderate challenge stringency) had a 0% probability of remaining disease free, versus a 50% probability in E6-vaccinated rabbits, and whereas GM-CSF alone had no effect, the interaction between GM-CSF priming and E6 vaccination increased disease-free survival to 67%. Second, the incubation period before papilloma onset was lengthened by E6 DNA vaccination alone or to some extent by GM-CSF DNA inoculation alone, and the combination of treatments induced additive effects. Third, the rate of papilloma growth was reduced by E6 vaccination and, to a lesser extent, by GM-CSF treatment. In addition, the interaction between the E6 and GM-CSF treatments was synergistic and yielded more than a 99% reduction in papilloma volume. Finally, regression occurred among the papillomas that formed in rabbits treated with the E6 vaccine and/or with GM-CSF, with the highest regression frequency occurring in rabbits that received the combination treatment.

Induction of E6/E7 expression in cottontail rabbit papillomavirus latency following UV activation

Latent human papillomavirus (HPV) infections are widespread in the genital and respiratory tracts and are a source of recurrent disease. This study used a cottontail rabbit papillomavirus (CRPV) model to determine the presence of E1, E6, and E7 transcripts in latent infection and to determine the temporal change in transcripts following UV activation. We found E1 transcripts in all latently infected sites but no detectable E6 and E7 transcripts, consistent with our earlier studies of HPV6/11 latency. These results suggest that this transcription pattern is broadly characteristic of latent papillomavirus infections. E6/E7 transcripts were detectable within 1 week of irradiation, with maximal induction (approximately 40% of sites) at 2 weeks postirradiation. Papillomas were induced in approximately 26% of irradiated sites after a 3- to 5-week lag. Sites that did not form papillomas by 3 months after irradiation were CRPV DNA positive but E6/E7 RNA negative. Thus, only a subset of latent infections can be induced to express E6/E7 transcripts and form papillomas. We propose that CRPV can be used to study the molecular processes regulating papillomavirus activation.

Intracutaneous vaccination of rabbits with the E6 gene of cottontail rabbit papillomavirus provides partial protection against virus challenge

DNA vaccination of rabbit skin with the L1 gene of cottontail rabbit papillomavirus (CRPV) has previously been shown to induce prophylactic immunity against CRPV. We now describe the effects of vaccination with the CRPV E6 gene, using the same approach. The experimental vaccine pdCMV-E6 encoded both the truncated and full length forms of CRPV E6 protein. The control vaccine pCMV-beta encoded beta galactosidase. Rabbits were vaccinated with DNA-coated gold particles, using a gene gun. Each rabbit received an initial vaccination with 30 micrograms DNA and 3 weeks later a booster vaccination, also with 30 micrograms DNA. pdCMV-E6-vaccinated rabbits developed E6-specific cellular immunity as determined by proliferation assays using peripheral blood mononuclear cells from animals prior to challenge, but did not develop detectable humoral immunity to E6 proteins, as evaluated by ELISA using two different E6 antigen preparations. Control rabbits developed humoral immunity to beta galactosidase. All rabbits were challenged by infection of nine skin sites with live CRPV virus and monitored for papilloma formation. None of four control rabbits was protected at any of the challenge sites. Of six rabbits vaccinated with pdCMV-E6, two were completely protected and one was virtually completely protected (tiny papillomas at just two of nine challenge sites). These three rabbits also exhibited significant E6-specific in vitro proliferative responses. The four E6 DNA-vaccinated rabbits that were not completely protected exhibited evidence of partial protection: some challenge sites did not form papillomas; papilloma onset was delayed; papilloma burden was less. These results demonstrate that partial prophylaxis against papillomavirus-induced disease can be achieved by intracutaneous vaccination with a recombinant plasmid encoding the papillomavirus.

Intracutaneous vaccination of rabbits with the cottontail rabbit papillomavirus (CRPV) L1 gene protects against virus challenge

A DNA vaccine encoding the major capsid protein L1 of cottontail rabbit papillomavirus (CRPV) was constructed and administered intracutaneously (i.c.) to rabbits as supercoiled plasmids bound to gold beads using a specialized delivery device ("gene gun"). L1 DNA-vaccinated rabbits developed cellular proliferative responses to CRPV virus-like particles and developed high titered antibodies with neutralizing activity to CRPV. Following experimental challenge with CRPV, all of the L1 DNA-vaccinated rabbits, vs none of the controls, were protected from papilloma formation. These results demonstrate that i.c. vaccination of rabbits with the L1 papillomavirus capsid gene can induce antibodies that protect against subsequent papillomavirus infection.

High efficiency, long-term clinical expression of cottontail rabbit papillomavirus (CRPV) DNA in rabbit skin following particle-mediated DNA transfer

The ability of skin to support long lasting expression of genes delivered with a particle-mediated system was evaluated in rabbits inoculated with cottontail rabbit papillomavirus (CRPV) DNA. The optimal delivery force for maximal gene expression in rabbit skin was determined in transient beta-galactosidase assays. Forty-five sites in four rabbits were then inoculated at 350-400 p.s.i. with CRPV DNA. All sites (100%) formed papillomas with multiple papillomas at most sites. These results support the feasibility of using a particle-mediated delivery system for gene therapy and suggest that some papillomavirus features, such an origin of replication, may be well suited for use in vectors to target long term expression to skin.

Particle-mediated delivery of recombinant expression vectors to rabbit skin induces high-titered polyclonal antisera (and circumvents purification of a protein immunogen)

Polyclonal antibodies were generated in rabbits by delivery to skin of gold particles coated with mammalian expression vectors encoding a cytoplasmic (beta-galactosidase) or a nuclear (L1 capsid of cottontail rabbit papillomavirus) protein. One primary and one booster immunization of 30 micrograms DNA per rabbit yielded specific antisera with titers from 1:24 000 to 1:120 000 in each of eight rabbits, as detected by ELISA and Western blot analysis. Genetic immunization requires relatively small amounts of DNA, eliminates the need to purify the protein immunogen, and does not require irritating adjuvants.

Rapid, efficient, large-scale purification of unfused, non-denatured E7 protein of cottontail rabbit papillomavirus

Cottontail rabbit papillomavirus (CRPV) E7 protein is one of the :high risk' papillomavirus E7 oncoproteins that are partially insoluble in aqueous solution. An Escherichia coli expression system was used for purification of CRPV E7 protein in quantities sufficient for immunologic studies and structural analysis. A glutathione S-transferase (GST)-CRPV E7 fusion protein was solubilized in the presence of non-ionic and ionic detergents, and isolated on an affinity column of glutathione Sepharose beads. The CRPV E7 portion was cleaved from the column with thrombin at a thrombin cleavage site between the fused partners. Thrombin was removed subsequently by adsorption to benzamidine. This method is rapid, requiring just one week, and efficient, yielding 3 mg of pure CRPV E7 protein per liter of bacterial culture. It produced a protein product that was about 95% pure. High-titered polyclonal antisera generated to the product recognized CRPV E7 but not GST. Purified CRPV E7 protein exhibited the ability to bind pRB, making it the first unfused, non-denatured CRPV E7 product reported to do so. This attribute could facilitate structure-function studies of CRPV E7-pRB interactions.

Papilloma formation in human foreskin xenografts after inoculation of human papillomavirus type 16 DNA

A mouse model of high-risk human papillomavirus infection was developed in which human papillomavirus (HPV) type 16 DNA was inoculated into human foreskin grafted to the skin of severe combined immunodeficient (scid) mice. Grafted skin contained human epidermis and dermis and, like normal human skin, expressed involucrin in differentiating keratinocytes. HPV type 16 DNA, attached to gold particles, was delivered directly into human epidermal cells and induced exophytic papilloma with histologic features of papillomavirus infection, including koilocytosis and expression of papillomavirus capsid antigen. This model should be useful for determining in vivo the functions of viral genes and for developing strategies to prevent and treat HPV-associated disease. It may also be of value in developing animal models of other human skin diseases.

Papilloma formation by cottontail rabbit papillomavirus requires E1 and E2 regulatory genes in addition to E6 and E7 transforming genes

The present study used the cottontail rabbit papillomavirus DNA-rabbit system to evaluate whether the regulatory genes E1 and E2 and the transforming gene E6 are required for papilloma formation. Frameshift mutations were generated in the individual genes in the context of a full-length cottontail rabbit papillomavirus genome, and the mutant DNAs were intradermally inoculated into domestic rabbits. None of the mutants induced papillomas. Marker rescue experiments confirmed that the defects were due to mutations that we deliberately introduced. Marker rescue also confirmed our previous report that the upstream region of E7 around position 9 was critical for papilloma induction. These results demonstrate that the E1 and E2 regulatory genes as well as the E6 and E7 transforming genes are each required for papilloma formation. Each gene may provide molecular targets for therapeutic intervention.

Characterization of acute rat parvovirus infection by in situ hybridization

In situ hybridization and virus titration were used to characterize early stages of rat virus (RV) infection of rat pups after oronasal inoculation. Results suggest that virus enters through the lung and that early viremia leads rapidly to pantropic infection. Cells derived from all three germ layers were infected with RV, but those of endodermal and mesodermal origin were the predominant targets. Infection of vascular endothelium was widespread and was associated with hemorrhage and infarction in the brain. Convalescence from acute infection was accompanied by mononuclear cell infiltrates at sites containing RV DNA. Viral DNA was also detected in endothelium, fibroblasts and smooth muscle myofibers four weeks after inoculation. Further examination of these cells as potential sites of persistent infection is warranted.

Papillomavirus E7 protein binding to the retinoblastoma protein is not required for viral induction of warts

Human papillomaviruses (HPVs) are the etiologic agents responsible for benign epithelial proliferative disorders including genital warts and are a contributory factor in the pathogenesis of cervical cancer. HPVs demonstrate strict species and cell-type specificity, which is manifested by the inability of these viruses to induce disease in any species other than humans. The natural history of HPV infection in humans is closely mimicked by cottontail rabbit papillomavirus (CRPV) infection in domestic laboratory rabbits. The CRPV E7 gene is known to play an essential role in virus-mediated induction of papillomas. We now show by mutational analysis that the CRPV E7 protein's biochemical and biological properties, including binding to the retinoblastoma suppressor protein (pRB), transcription factor E2F transactivation of the adenovirus E2 promoter, disruption of pRB-E2F complexes, and cellular transformation as measured by growth in soft agar, mimic those of the HPV E7 protein. Intradermal injection of CRPV DNA lacking E7 gene sequences critical for the binding of the CRPV E7 protein to pRB induced papillomas in rabbits. These studies indicate that E7 protein binding to pRB is not required in the molecular pathogenesis of virally induced warts and suggest that other properties intrinsic to the E7 protein are necessary for papilloma formation.

Infectious virus replication in papillomas induced by molecularly cloned cottontail rabbit papillomavirus DNA

The ability to obtain infectious papillomavirus virions from molecularly cloned DNA has not been previously reported. We demonstrate here that viral genomes isolated from a recombinant++ DNA clone of cottontail rabbit papillomavirus (CRPV) gave rise to infectious virus when inoculated into cottontail rabbit skin. Replication occurred in papillomas that formed at inoculation sites. Extract of a DNA-induced papilloma was serially passaged to naive rabbits with high efficiency. Complete virus was fractionated on cesium chloride density gradients, and papillomavirus particles were visualized by electron microscopy. CRPV DNA isolated from virions contained DNA sequence polymorphisms that are characteristic of the input CRPV-WA strain of virus, thereby proving that the newly generated virus originated from the molecularly cloned viral genome. These findings indicate that this will be a useful system in which to perform genetic analysis of viral gene functions involved in replication.

The putative E5 open reading frame of cottontail rabbit papillomavirus is dispensable for papilloma formation in domestic rabbits

In the cottontail rabbit papillomavirus (CRPV)-rabbit system, recombinant CRPV DNA can induce papillomas. This investigation was undertaken to evaluate whether the E5 open reading frame (ORF) of CRPV is required for papilloma formation. The CRPV genome we utilized, CRPV-WA, was sequenced in the E5 region and was found to contain one deletion, two insertions, and one transition mutation compared with CRPV-KS, the CRPV genome that has been fully sequenced. Despite these differences, an intact E5 ORF is preserved, supporting the notion that this gene may serve a biological function. One frameshift and two in-frame mutations were constructed in the small region of the 5' end of the E5 ORF that follows the E2 stop codon and precedes the L2 ORF. Several hundred rabbit skin sites were inoculated with each DNA preparation with a jet injector to test the ability of three CRPV E5 mutant DNAs to induce papillomas. In vivo results showed that each of the mutants induced papillomas, and biochemical analysis demonstrated that the E5 mutations present in DNA inocula were retained in the papillomas. The frequency of papilloma formation, however, was generally lower with each of the CRPV E5 mutants than with wild-type CRPV DNA, particularly so for the E5 frameshift mutant, suggesting that although the recognized E5 ORF is not required in domestic rabbits for the induction of papillomas by CRPV DNA, it may facilitate their formation.

Persistent rat parvovirus infection in individually housed rats

The duration of infection with rat virus (RV), an autonomous rodent parvovirus, was examined at multiple intervals over 6 months in rats inoculated by the oronasal route at 2 days of age or 4 weeks of age and individually housed after weaning to prevent cross-infection. Infectious virus was recovered by explant culture from 32 of 80 rats inoculated as pups and was detected as late as 6 months after inoculation. Rats inoculated as juveniles developed acute infection, but virus was not detected beyond 7 weeks after inoculation. Tissues from rats in both age groups were surveyed for RV DNA by Southern blotting using a double-stranded DNA probe made from a 1700 bp cloned fragment of RV spanning map units 0.19-0.52. Band patterns representative of acute infection (juvenile rats) were consistent with the replicating form of RV DNA, whereas patterns representative of persistent infection (rats inoculated as pups) were suggestive of defective or non-productive viral replication.

Use of a rapid, efficient inoculation method to induce papillomas by cottontail rabbit papillomavirus DNA shows that the E7 gene is required

A simple inoculation method to induce papillomas efficiently with cottontail rabbit papillomavirus (CRPV) DNA is described. Using a jet injector, recombinant CRPV DNA is easily delivered to 100 or more sites per rabbit and induces typical epithelial papillomas in approximately 50% of those sites. Papillomas begin to form by 3 weeks and continue to develop for up to 7 weeks, a pattern similar to that reported following infection with intact virus. This system readily lends itself to investigation of viral gene function by delivering mutant viral genomes into an immunologically intact host. Two mutations in the E7 open reading frame were introduced into the complete CRPV genome and analyzed by this method. One was a frameshift mutation encoding just nine amino-terminal amino acids of the E7 protein; the other was an in-frame insertion mutation at position 9. Both E7 mutations were in a region of homology to the 300-kDa protein binding domain of adenovirus E1A protein. Neither mutant construct was able to induce papillomas, thereby demonstrating that the E7 gene participates in this biologic function. Exploitation of this approach, which demonstrates that a papillomavirus E7 gene is involved in the induction of papillomas in vivo, should permit detailed studies into molecular mechanisms involved in papilloma induction, malignant conversion, and host immune response. The high efficiency of papilloma induction with recombinant CRPV DNA suggests that the jet injector can also be used to study the biologic effects of other genetic elements in rabbits or in other species.

Modulation of lethal and persistent rat parvovirus infection by antibody

Two day-old athymic (rnu/rnu) and euthymic (rnu/+) rat pups nursing immune or non-immune dams were inoculated oronasally with the Yale strain of rat virus (RV-Y). All athymic and euthymic pups (57/57) from immune dams remained clinically normal, whereas 51 of 66 athymic and euthymic pups from non-immune dams died within 30 days. Infectious RV was detected by explant culture in 12 of 15 surviving pups of both genotypes from non-immune dams 30 days after inoculation, but in none of the 57 surviving pups from immune dams. RV-Y DNA was detected by Southern blotting in kidneys of surviving athymic pups from non-immune dams but was not detected in pups from immune dams. Euthymic pups from immune dams appeared not to produce endogenous antibody to RV after virus challenge, whereas euthymic pups from non-immune dams produced high-titered RV immune serum. Pups of both genotypes given immune serum prior to or with RV were fully protected from disease and persistent infection, whereas pups given immune serum 24 hours after RV were partially protected. These studies show that RV antibody offers significant protection against lethal and persistent RV infection.

Detection of conditions related to human papillomavirus. Comparison of cytology, colposcopy, histology and hybridization

The diagnosis of lesions associated with human papillomavirus infection can be difficult because the results of the tests used can be contradictory. Our goal was to compare some of these tests and to evaluate their comparative strengths and weaknesses as clinically useful tools in confirming the diagnosis, especially in borderline cases. Twenty-one consecutive patients from our colposcopy clinic were screened with cytology and colposcopy. Biopsies were taken from representative areas on the cervix and vulva and divided. One-half was evaluated with Southern blot hybridization and the other half with histology and with RNA and DNA in situ hybridization. Cytology and histology were interpreted as either "positive" (showing definite evidence of human papillomavirus infection or cervical intraepithelial neoplasia [CIN]), "negative" (showing no evidence of human papillomavirus infection or CIN) or "equivocal" (atypical [class II] Papanicolaou smears or histology suggestive but not diagnostic of condyloma). In order to determine the clinical significance of equivocal results the sensitivity and specificity of these tests were calculated, with the equivocal results reclassified as either positive or negative. Colposcopy was the most sensitive technique but was not very specific. Cytology was a very sensitive screening tool when the atypical (class II) smears were considered positive but not when they were considered negative. The specificity of the histologic diagnosis was doubled with the equivocal results considered negative when compared to the specificity of the histologic diagnosis with the equivocal results considered positive, with no loss of sensitivity. Each technique has drawbacks, and therefore no one should be used to diagnose and treat these lesions to the exclusion of all others.

Detection and typing of papillomavirus DNA in formaldehyde-fixed paraffin-embedded tissue

Clinical specimens from nine patients with papillomatosis of the vocal cords and three patients with vocal cord polyps were evaluated for the presence of human papillomavirus (HPV) DNA using two complementary molecular hybridization techniques. In one method, involving polymerase chain reaction (PCR) amplification, HPV DNA sequences were replicated in vitro from tissue DNA extracted from paraffin sections prior to hybridization. Polymerase chain reaction amplification was compared with the standard method of Southern blot hybridization. Results of the two techniques for all nine laryngeal papillomas agreed completely: five patients harbored HPV type 6 and four HPV type 11. Both PCR amplification and Southern blot hybridization found two of the three polyps to be free of HPV infection, while PCR detected HPV type 18 in one polyp specimen that was reported negative by Southern blot hybridization, suggesting a greater sensitivity of PCR. Our results demonstrate that PCR amplification is as reliable and at least as sensitive as Southern blot hybridization. Moreover the PCR technique opens the way to the undertaking of a whole variety of retrospective studies using formaldehyde-fixed paraffin-embedded tissues.

Assessment of criteria used in the histologic diagnosis of human papillomavirus-related disease of the female lower genital tract

The goal of this study was to evaluate the histologic criteria used to establish the diagnosis of human papillomavirus (HPV)-associated disease, especially in borderline lesions. In a completely blinded study, 21 patients had one biopsy each of the cervix and vulva. Each specimen was evaluated by RNA and DNA in situ hybridization, a histologic diagnosis was rendered, and then each was evaluated for 12 histologic criteria commonly associated with HPV. On the cervix only binucleation and dysplasia correlated well with in situ hybridization. Koilocytosis correlated very strongly with the histologic diagnosis. On the vulva, koilocytosis, papillomatosis, elongated rete pegs, binucleation, and hypergranulosis correlated well with in situ hybridization. When four other pathologists reviewed the slides, they agreed on the histologic diagnosis and the presence of koilocytosis, binucleation, and dysplasia on the cervix but on none of the other criteria. On the vulva the pathologists disagreed on the overall diagnosis and the presence of any of the criteria with the exception of papillomatosis. Nonclassic histologic criteria should not, by themselves, be used to make the diagnosis of condyloma. The use of such terminology as "suggestive of condyloma" in histologic diagnoses should be avoided in favor of more descriptive terminology to avoid possibly unnecessary treatment for lesions of questionable significance.

Association of papillomavirus with cancers of the head and neck

One hundred one squamous cell carcinomas (SCC) (study group) and 116 tissues without SCC or papilloma from matched anatomic sites (control group) were evaluated for the presence of human papillomavirus (HPV) DNA. Squamous cell carcinomas of the tongue (18%), tonsil (29%), and pharynx (13%) specifically harbored HPV-16-related sequences. In contrast, the nose, mouth, and esophagus proved completely negative. In the larynx, a low prevalence of HPV-11/16-related DNA was found in both cancers (5%) and control tissues (4%), suggesting that the associations lacked specificity. Our results indicate that anatomic site plays a role in determining the susceptibility to infection, and that the clinical entities with which HPV infections are associated include both subclinical infection with no history of papilloma, and malignant disease.

Tissue site-specific enhancer function of the upstream regulatory region of human papillomavirus type 11 in cultured keratinocytes

The human papillomavirus type 11 regulatory region was cloned upstream of a reporter complex and microinjected into nuclei of individual primary human keratinocytes. Genital and laryngeal keratinocytes, normal host cells for this virus, exhibited higher levels of expression than cutaneous keratinocytes. We conclude that a papillomavirus enhancer(s) shows preferences among epithelial cells from different tissue sites.

Disseminated warts and evolving squamous cell carcinoma in a patient with acquired immunodeficiency syndrome

A patient with acquired immunodeficiency syndrome developed widespread verrucous lesions on the hands, feet, and penis. Histologic analysis revealed typical changes of verruca vulgaris and, from several sites, a transformation toward squamous cell carcinoma. Southern blot analysis of deoxyribonucleic acid from penile wart tissue indicated the presence of a type of human papillomavirus that rarely is associated with carcinoma.

Presence of human papillomavirus type 16 related sequences in verrucous carcinoma of the larynx

Verrucous carcinoma of the larynx clinically resembles laryngeal papilloma in that both are wart-like masses on the vocal cords and may be characterized by multifocality and recurrence. Human papillomavirus (HPV) infection is an etiological factor in laryngeal papilloma, and recent evidence implicates HPV in squamous neoplasias. To determine whether HPV is also associated with verrucous carcinoma of the larynx, we analyzed tissue specimens from six patients with verrucous carcinoma of the larynx by Southern and DNA dot blot hybridization for HPV DNA. From three patients, specimens of normal laryngeal epithelium were also studied. All tissues showed evidence of HPV sequences related but not identical to HPV-16. They were negative for HPV-11. In contrast, four squamous cell carcinomas of the larynx and three normal laryngeal tissues were negative for HPV DNA. Histological sections of the six verrucous lesions were found to contain koilocytosis. Immunoperoxidase staining for HPV capsid antigens was negative in all these cases. The consistent and specific association of HPV with the verrucous carcinomas in this report suggests the possibility of a pathogenic involvement.

Interferons in the treatment of human papillomavirus diseases

A variety of epithelioproliferative benign neoplasms, both trivial and life-threatening, are caused by subtypes of human papillomaviruses. Interferons objectively regress HPV-induced warty disease and affect the regrowth of the transformed epithelium. Interferons effectively control the most serious and potentially life-threatening papillomavirus associated diseases, respiratory papillomatosis and genital warts, but not without the anticipated side effects associated with this potent biological weapon. It is entirely possible and even likely that individual species of interferons act preferentially on certain cells, tissues or organs in response to particular viruses. Combined therapies, such as surgery in combination with interferon, or podophyllin in conjunction with interferon alfa-n1, may prove most efficacious.