The human papillomavirus type 11 E1/\E4 protein is not essential for viral genome amplification.

An abundant human papillomavirus (HPV) protein E1/\E4 is expressed late in the virus life cycle in the terminally differentiated layers of epithelia. The expression of E1/\E4 usually coincides with the onset of viral DNA amplification. However, the function of E1/\E4 in viral life cycle is not completely understood. To examine the role of E1/\E4 in the virus life cycle, we introduced a single nucleotide change in the HPV-11 genome to result in a truncation of E1/\E4 protein without affecting the E2 amino acid sequence. This mutated HPV-11 genome was introduced into a human foreskin keratinocyte cell line immortalized by the catalytic subunit of human telomerase, deficient in p16(INK4a) expression, and previously shown to support the HPV-11 life cycle when grown in organotypic raft culture. We have demonstrated that E1/\E4 is dispensable for HPV-11 viral DNA amplification in the late stages of the viral life cycle.

Induction of productive human papillomavirus type 11 life cycle in epithelial cells grown in organotypic raft cultures.

The study of the human papillomavirus (HPV) life cycle was hampered for more than 50 years by the lack of a conventional cell culture system for propagating HPV. Considerable progress has been made in the production of several HPV types using either organotypic rafts or human epithelial xenografts in immunocompromised mice. In this study, we demonstrated episomal maintenance of HPV-11 DNA in N-Tert cells. HPV-11 episomal DNA containing cell populations grown in raft culture showed induction of the productive viral life cycle. HPV-11 DNA amplification and viral capsid antigen synthesis were detected in differentiated layers of epithelia. The viruses generated were able to infect keratinocytes in vitro, which indicate that viruses generated were infectious. The demonstration of the productive HPV-11 life cycle in raft culture from cloned HPV-11 DNA will facilitate genetic analyses of viral gene functions that was not possible using the human xenograft athymic mouse model.

Suppression of human papillomavirus gene expression in vitro and in vivo by herpes simplex virus type 2 infection.

Recent epidemiological studies have found that women infected with both herpes simplex virus type 2 (HSV-2) and human papillomavirus (HPV) type 16 or HPV-18 are at greater risk of developing cervical carcinoma compared to women infected with only one virus. However, it remains unclear if HSV-2 is a cofactor for cervical cancer or if HPV and HSV-2 interact in any way. We have studied the effect of HSV-2 infection on HPV-11 gene expression in an in vitro double-infection assay. HPV transcripts were down-regulated in response to HSV-2 infection. Two HSV-2 vhs mutants failed to reduce HPV-16 E1;E4 transcripts. We also studied the effect of HSV-2 infection on preexisting experimental papillomas in a vaginal epithelial xenograft model. Doubly infected grafts demonstrated papillomatous transformation and the classical cytopathic effect from HSV-2 infection. HPV and HSV DNA signals were mutually exclusive. These studies may have therapeutic applications for HPV infections and related neoplasms.

Immunological characterization of human vaginal xenografts in immunocompromised mice: development of a small animal model for the study of human immunodeficiency virus-1 infection.

A small animal model for the in vivo study of human immunodeficiency virus-1 and other fastidious infectious agents in human host target tissues is critical for the advancement of therapeutic and preventative strategies. Our laboratory has developed a human vaginal xenograft model that histologically recapitulates features of the human vaginal epithelial barrier. Vaginal xenografts were surgically implanted into C.B.-Igh-1(b)/IcrTac-Prkdc(scid) (SCID) and NOD/LtSz-scid/scid (NOD/SCID) mice, with and without human peripheral blood mononuclear cell reconstitution. Immunohistochemical staining of vaginal xenografts demonstrated that in the SCID strain healed vaginal xenografts did not retain intrinsic human immune cells at baseline levels, whereas the NOD/SCID strain supported retention of intrinsic human immune cell populations within the xenografts for at least 2 months after engraftment. In peripheral blood mononuclear cell-reconstituted NOD/SCID mice with vaginal xenografts, flow cytometric analyses detected human immune cell populations in the peripheral blood and immunohistochemical methods detected infiltration of human CD45+ cells in the mouse spleens and vaginal xenografts for at least 2 months after reconstitution. This optimized NOD/SCID human vaginal xenograft model may provide a unique small animal in vivo system for the study of human immunodeficiency virus-1 transmission and infection.

Hybrid papillomavirus L1 molecules assemble into virus-like particles that reconstitute conformational epitopes and induce neutralizing antibodies to distinct HPV types.

Human papillomavirus (HPV) hybrid virus-like particles (VLPs) were prepared using complementary regions of the major capsid L1 proteins of HPV-11 and -16. These hybrid L1 proteins were tested for assembly into VLPs, for presentation and mapping of conformational neutralizing epitopes, and as immunogens in rabbits and mice. Two small noncontiguous hypervariable regions of HPV-16 L1, when replaced into the HPV-11 L1 backbone, produced an assembly-positive hybrid L1 which was recognized by the type-specific, conformationally dependent HPV-16 neutralizing monoclonal antibody (N-MAb) H16.V5. Several new N-MAbs that were generated following immunization of mice with wild-type HPV-16 L1 VLPs also recognized this reconstructed VLP, demonstrating that these two hypervariable regions collectively constituted an immunodominant epitope. When a set of hybrid VLPs was tested as immunogens in rabbits, antibodies to both HPV-11 and -16 wild-type L1 VLPs were obtained. One of the hybrid VLPs containing hypervariable FG and HI loops of HPV-16 L1 replaced into an HPV-11 L1 background provoked neutralizing activity against both HPV-11 and HPV-16. In addition, conformationally dependent and type-specific MAbs to both HPV-11 and HPV-16 L1 VLP were obtained from mice immunized with hybrid L1 VLPs. These data indicated that hybrid L1 proteins can be constructed that retain VLP-assembly properties, retain type-specific conformational neutralizing epitopes, can map noncontiguous regions of L1 which constitute type-specific conformational neutralizing epitopes recognized by N-MAbs, and trigger polyclonal antibodies which can neutralize antigenically unrelated HPV types.

In vivo anti-papillomavirus activity of nucleoside analogues including cidofovir on CRPV-induced rabbit papillomas.

A series of nucleoside analogues were tested for in vivo anti-papillomavirus activity using the cottontail rabbit papillomavirus (CRPV) domestic rabbit model. Compounds were delivered either topically, injected into growing papillomas, or delivered subcutaneously at a site remote from the papillomas. Compounds tested included cidofovir [(S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine] (HPMPC); cyclic HPMPC (cHPMPC); cyclopentenylcytosine (CPE-C); lobucavir [1R(1alpha,2beta,3alpha)]-9-[2, 3-bis(hydroxymethyl)cyclobutyl]guanine; 9-((2-phosphonylmethoxy)propyl)adenine (PMPA); adefovir 9-((2-phosphonylmethoxy)ethyl)adenine(PMEA) and cyclopropyl 9-(2-phosphonylmethoxyethyl)-2,6-diaminopurine (cyclopropylPMEDAP). Dose response curves and time-course treatments were included for most compounds tested. Strong anti-viral activity was detected using cidofovir and cHPMPC when delivered either topically or by the intralesional route. Complete cures were obtained using 1% (w/v) topical cidofovir at dosing schedules of twice daily for 8 weeks beginning at 4 weeks after CRPV infection, which represents a time when papillomas were clearly visible. Complete cures of large established papillomas were obtained by intralesional injection of 1% cidofovir three times per week for 8 weeks. Topical treatments with adefovir had strong anti-viral activity, cyclopropyl PMEDAP had moderate anti-viral activity, and CPE-C, PMPA and lobucavir showed no effects. These data indicate that certain nucleoside analogues have strong in vivo anti-papillomavirus activity and that the CRPV/rabbit model is a good model for assessing clinical responses of anti-viral treatments for patients with HPV disease.

DNA vaccination prevents and/or delays carcinoma development of papillomavirus-induced skin papillomas on rabbits.

Malignant progression is a life-threatening consequence of human papillomavirus-associated lesions. In this study, we tested the efficacy of papillomavirus early-gene-based vaccines for prevention of carcinoma development of papillomavirus-induced skin papillomas on rabbits. Rabbit skin papillomas were initiated by infection with cottontail rabbit papillomavirus (CRPV). The papillomas were allowed to grow for 3 months without any treatment intervention. Rabbits were then immunized by gene gun-mediated intracutaneous administration of four DNA plasmids encoding CRPV E1, E2, E6, and E7 genes, respectively. All eight control rabbits receiving vector alone developed invasive carcinoma within 8 to 13 months. In contrast, only two of eight vaccinated rabbits developed carcinoma at 12 and 15 months, respectively. Papilloma growth was suppressed in the majority of vaccinated rabbits but not completely eradicated. These results indicate that gene gun-mediated immunization with papillomavirus early genes may be a promising strategy for prevention of malignant progression of human papillomavirus-associated lesions in humans.

A broad-spectrum microbicide with virucidal activity against sexually transmitted viruses.

Sodium dodecyl sulfate (SDS), an alkyl sulfate surfactant derived from an organic alcohol, possesses surfactant properties but also denatures and unfolds both monomeric and subunit proteins. In preliminary experiments, we demonstrated that SDS is a potent inactivator of herpes simplex virus type 2 and human immunodeficiency virus type 1 at concentrations comparable to those used for the surfactant nonoxynol-9. We hypothesized that SDS might be capable of denaturing the capsid proteins of nonenveloped viruses. In this report, we demonstrate inactivation of rabbit, bovine, and human papillomaviruses after brief treatment with dilute solutions of SDS. Effective concentrations were nontoxic to rabbit skin and to split-thickness grafts of human foreskin epithelium. This is the first report of a microbicidal surfactant that will inactivate papillomaviruses. We propose that SDS is now a candidate microbicide for formulation and testing with humans.

Agarose-embedded tissue arrays for histologic and genetic analysis.

To facilitate the histologic analysis of large numbers of 7-day-old zebrafish (Danio rerio), a method has been developed to process them in agarose-embedded arrays. Using thin tissue sections, the morphology of cells and tissues can be examined microscopically to investigate a variety of biologic processes. Because of their small size, precise arrangement of the larvae is necessary to section them simultaneously. A technique was designed to embed groups of zebrafish larvae in a single plane in agarose before sectioning. Stained tissue sections of thousands of larvae can be examined efficiently using this embedding method. In addition to histologic analysis, PCR-based genotypic analysis of DNA from individual larval sections is also possible. This technique can be modified to accommodate any study that requires the histologic examination of many pieces of tissue.

Rabbit genital tissue is susceptible to infection by rabbit oral papillomavirus: an animal model for a genital tissue-targeting papillomavirus.

Rabbit oral papillomavirus (ROPV) is a mucosatropic papillomavirus which naturally infects oral mucosal sites of domestic rabbits. In this study, we tested the hypothesis that rabbit genital mucosa is also susceptible to ROPV infection by using the athymic mouse xenograft system and adult immunocompetent rabbits. Subrenal xenografts of ROPV-infected rabbit vulvar and penile sheath tissues were strongly positive for ROPV infection by histologic, in situ hybridization, and Southern analyses. Direct inoculation of adult rabbit penises with infectious ROPV produced small raised lesions of approximately 1 by 1 by 1 mm that were ROPV positive by both in situ hybridization and Southern analyses and were also viral capsid antigen positive by immunohistological staining. Infection of rabbit genital tissues with ROPV may be a useful animal model for the study of genital tissue-targeting papillomaviruses.

Coinfection of human foreskin fragments with multiple human papillomavirus types (HPV-11, -40, and -LVX82/MM7) produces regionally separate HPV infections within the same athymic mouse xenograft.

The athymic mouse xenograft system was used to prepare infectious stocks of two additional anogenital tissue-targeting human papillomaviruses (HPVs) in a manner similar to that for the development of infectious stocks of HPV-11. An anal condyloma from a transplant patient was used as material for extraction of infectious virus, and human foreskin fragments were incubated with the virus suspension and transplanted subrenally into athymic mice. Partial viral sequencing indicated that two rare HPV types (HPV-40 and HPVLVX82/MM7) were concurrently present in both the patient condyloma and the foreskin xenografts, and passage of both types was achieved as a mixed infection with HPV-40 predominating. Xenografts that developed from simultaneous infection of human foreskin fragments with HPV-11, -40, and -LVX82/MM7 virions produced regionally separate areas of HPV-11 and -40 infection as determined by in situ hybridization. In addition, in situ hybridization with HPV-40 and HPVLVX82/MM7 DNA probes demonstrated that both of these HPV types were present as adjacent but separate infections within the same anal condyloma of the transplant patient. These studies indicate that multiple HPV types can simultaneously infect genital tissue and that each HPV type predominantly maintains regional separation within the same papilloma.

Laboratory production of infectious stocks of rabbit oral papillomavirus.

Several small, raised lesions from the underside of the tongue of domestic rabbits were isolated, and an extract prepared and tested for the presence of rabbit oral papillomavirus (ROPV). Two weeks after inoculation of this extract into the underside of rabbit tongues, multiple small discrete, grey-white nodules were observed that reached a maximum size of 2 mm in diameter by 5 weeks. These lesions showed typical ROPV pathology, and nuclei stained positive for papillomavirus (PV) group-specific antigen (GSA) by immunocytochemistry. Tissue fragments from rabbit tongues were incubated with a suspension of ROPV and placed subrenally into athymic mice. After 60 days, cysts were removed, sections cut for histology, and a virus stock prepared. GSA staining and in situ hybridization demonstrated that the xenografts were morphologically transformed with areas showing strong nuclear staining for viral capsid antigen and ROPV DNA. Extracts prepared from the pooled xenografts contained infectious ROPV as demonstrated by inoculation into the undersurface of tongues of nonimmune New Zealand White rabbits. The results demonstrated that stocks of infectious ROPV can be prepared in the athymic mouse xenograft system for use in studies on the experimental transmission of a mucosal-targeting animal papillomavirus.

Association of tumor necrosis factor-alpha gene expression and apoptotic cell death with regression of Shope papillomas.

The objective of this study was to test the hypothesis that spontaneous regression of Shope papillomas involves tumor necrosis factor-alpha and apoptotic cell death of the papilloma cells. In situ hybridization using RNA probes of rabbit tumor necrosis factor-alpha revealed tumor necrosis factor-alpha mRNA in most of the numerous mononuclear cells infiltrating the upper dermis of regressing papillomas and at the dermoepidermal junction. Such cells in progressing papillomas were much fewer in number and were located in the deeper dermis. In situ terminal deoxynucleotidyl transferase assay demonstrated DNA strand breaks in many scattered epidermal keratinocytes of regressing papillomas but in only a few thin layers just beneath the horny layer in progressing papillomas. Electron microscopy demonstrated that regressing papillomas contained many apoptotic bodies and keratinocytes showing apoptotic changes such as chromatin condensation, degradation of condensed nuclei, surface protuberances, and a filamentous degeneration, as well as infiltrating lymphocytes and macrophages. We propose that tumor necrosis factor-alpha produced by infiltrating mononuclear cells probably plays a role in the papilloma regression.

Assembled baculovirus-expressed human papillomavirus type 11 L1 capsid protein virus-like particles are recognized by neutralizing monoclonal antibodies and induce high titres of neutralizing antibodies.

Baculovirus-expressed human papillomavirus type 11 (HPV-11) major capsid protein (L1) virus-like particles (VLPs) were produced in insect cells and purified on CsCl density gradients. The VLPs retained conformational neutralizing epitopes that were detected by a series of HPV-11-neutralizing monoclonal antibodies. Electron microscopy determined that the HPV-11 L1 VLPs were variable in size with a surface topography similar to that of infectious HPV-11. The VLPs were very antigenic, and induced high titres of neutralizing antibodies in rabbits and mice when used as an immunogen without commercial preparations of adjuvant. These VLP reagents may be effective vaccines for protection against HPV infections.

Podofilox-induced regression of Shope papillomas may be independent of host immunity.

We tested the hypothesis that infiltrating leukocytes might contribute to papilloma destruction following podofilox treatment. New Zealand White (NZW) rabbits were inoculated with cottontail rabbit papillomavirus (CRPV) onto abraded areas of the dorsal skin. At 21 d after viral inoculation, 5.0% podofilox solution was applied to some papillomas, whereas others were used as controls. Three rabbits were sacrificed at each of three different periods after treatment initiation (1, 4, and 7 d). Four monoclonal antibodies (MoAbs), RG-16 (for B cells), L11/135 (specific for T cells), 2C4 (specific for class II antigen), and Ki67 (specific for proliferating cells), were used in an immunohistochemical study. All positive cells and total cells in the field were counted with an ocular grid. After 1 d of treatment, proliferation of papilloma cells was strongly suppressed in treated papillomas, but leukocytic infiltration was not altered. At 4 d and 7 d of treatment, there were substantial increases (about two to three times) in the numbers of B and T cells and class II-expressing leukocytes. The upper layers of the papillomas were highly necrotic and cell proliferation was absent in all layers. These data support the view that podofilox has a direct toxic effect on papilloma tissue. Leukocyte infiltration is not strongly associated with papilloma tissue and may not contribute to papilloma destruction.

Shope papilloma cell and leukocyte proliferation in regressing and progressing lesions.

Lesions generated by infection with cottontail rabbit papillomavirus frequently undergo spontaneous regression. The purpose of this immunohistochemical study was to compare leukocyte and papilloma cell proliferation in progressing and regressing papillomas and to test the hypothesis that regression was associated with an inhibition of papilloma cell proliferation. The monoclonal antibodies (MAbs) MAb-019 (specific for DNA/bromodeoxyuridine [BrdU] complexes), Ki-67 (specific for actively proliferating cells), L11/135 (specific for rabbit T cells), and 2C4 (specific for rabbit class II antigen) were used for this purpose. In progressing papillomas, there were few leukocytes (< 1%) in the dermis that stained with MAb-019 and Ki-67, whereas these antibodies stained 4.5% and 6.8% of the intraepidermal leukocytes, respectively. Regressing papillomas contained conspicuous leukocytic infiltrates in the dermis, of which 76.9% were L11/135-positive T cells. However, few intradermal leukocytes (< 3%) stained positively with MAb-019 and Ki-67 MAbs, despite expressing rabbit class II antigen. The epidermis of regressing papillomas contained a higher percentage of MAb-019- and Ki-67-positive leukocytes than the epidermis of progressing papillomas. Intraepidermal leukocytes in progressing and regressing papillomas consisted mainly of T cells stained by L11/135. It appeared that many dermal leukocytes (mainly T cells) form a non-cycling T cell population in both progressing and regressing papillomas, whereas intraepidermal T cells in regressing papillomas were effectively activated and represented a cycling T cell population. MAb-019 and Ki-67 MAbs demonstrated similar staining patterns in papilloma and normal tissues. However, in both progressing and regressing papillomas, the Ki-67 MAb usually stained a larger percentage of cells than the MAb-019 MAb. MAb-019 and Ki-67 MAbs showed a homogeneous distribution of positive cells from basal layer to the upper layer in progressing papillomas. On the other hand, in regressing papillomas, cell staining with the two antibodies was concentrated in the basal and lower layers, but not in the upper layers. This result indicates that cell proliferation in the upper epidermal layers is suppressed in regressing papillomas. Our present data show that intraepidermal T- cell activation and suppression of tumor proliferation might play a crucial role in papilloma regression.

Detection of Epstein-Barr virus genomes by in situ DNA hybridization with a terminally biotin-labeled synthetic oligonucleotide probe from the EBV Not I and Pst I tandem repeat regions.

We describe a case of acute, disseminated Epstein-Barr virus (EBV) infection which was analyzed for the cellular distribution of viral replication by automated, colorimetric in situ DNA hybridization using a single, synthetic, terminally biotin-labeled oligonucleotide probe composed of 23 consecutive nucleotides selected from the EBV Not I region. The GC-rich, Not I region is a 125-base pair sequence that is repeated in tandem an average of 12.6 times in the EBV genome. The synthetic sequence had 91% base homology with another EBV genomic tandem repeat, the 102-base pair Pst I region, which is also GC-rich, has an overall 70% homology with the Not I region, and is reiterated about 25 times in the viral DNA. Disseminated EBV infection was detected in nuclei of atypical lymphocytes in several organs, including lung, bronchus, trachea, spleen, liver, and stomach, with the probes. In addition, the synthetic oligomer compared favorably with a significantly more expensive, nick translated, biotinylated probe cloned from the BAM HI-V (W), large internal repeat region. This 3.0-kilobase pair (kbp) sequence is repeated an average of 11 times in EBV. Although both probes identified regions repeated multiple times in the virus, and each confirmed an identical tissue distribution for the infection, the signal obtained with the Not I/Pst I probe was more intense and confined to the nuclei of fewer lymphocytes than the general, more weakly distributed signal obtained with the probe from the large internal repeat region. Consistent positive cellular staining was obtained with the Not I/Pst I probe in both EBV-infected control tissue culture cells and in formalin-fixed, paraffin-embedded tissue sections.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomic viral detection is automated: the application of a robotic molecular pathology system for the detection of DNA viruses in anatomic pathology substrates, using immunocytochemical and nucleic acid hybridization techniques.

This paper presents the first automated system for simultaneously detecting human papilloma, herpes simplex, adenovirus, or cytomegalovirus viral antigens and gene sequences in standard formalin-fixed, paraffin-embedded tissue substrates and tissue culture. These viruses can be detected by colorimetric in situ nucleic acid hybridization, using biotinylated DNA probes, or by indirect immunoperoxidase techniques, using polyclonal or monoclonal antibodies, in a 2.0-hour assay performed at a single automated robotic workstation.

Tumor-associated antigens in breast carcinomas. Prognostic significance.

In an attempt to identify biologic markers that might predict prognosis in breast cancer patients, the presence or absence of seven tumor-associated antigens in 54 infiltrating breast carcinomas was correlated with tumor recurrence rates (minimum five-year follow-up), axillary lymph node metastases and tumor volume. Immunohistochemical kappa-casein was present in 30 (56%) tumors, alpha-lactalbumin in 39 (72%) tumors, secretory component of IgA in 26 (48%) tumors, carcinoembryonic antigen in 34 (63%) tumors, pregnancy-specific beta-1-glycoprotein in 7 (13%) tumors, beta subunit of human chorionic gonadotrophin in 1 (2%) tumor and human placental lactogen in 0 (0%) tumors. There was no significant correlation between the presence or absence in tumor of any of the antigens, and prognosis as assessed either by 5-year recurrence rates (P greater than 0.18) or by the presence of axillary lymph node metastases (P greater than 0.20). No significant difference was noted in mean tumor volume (cm3) +/- SEM, between tumors with or without antigen immunoreactivity (P greater than 0.05).

Viral diagnosis by in situ hybridization. Description of a rapid simplified colorimetric method.

An improved method of colorimetric in situ hybridization for the diagnosis of viral infections in standard formalin-fixed, paraffin-embedded tissue sections has been developed. This method employs a 2-hour hybridization with biotin-labeled DNA probes followed by direct colorimetric detection with avidin-alkaline phosphatase complexes. Visual results are obtained within 8 h of cutting the tissue section. Specific histologic localization of cytomegalovirus and adenovirus genetic information has been achieved in infected lung tissues from autopsy or biopsy. Simultaneous denaturation of tissue and probe DNA at elevated temperature (100-105 degrees C) resulted in increased signal. It is our suggestion that these denaturing conditions may be required to denature more fully formalin cross-linked tissue DNA and favor penetrance of probe into the tissues. Comparison of the results of hybridization and viral culture for the diagnosis of CMV infections suggest that in clinical situations hybridization will allow specific diagnosis of productive viral infection more rapidly than viral culture with some loss in sensitivity. Colorimetric in situ DNA hybridization offers the surgical pathologist a powerful new technique that provides an alternative to immunocytochemistry and electron microscopy in the diagnosis of viral pathogens.