Rhizosphere microbial communities associated to rose replant disease: links to plant growth and root metabolites

Growth depression of Rosa plants at sites previously used to cultivate the same or closely related species is a typical symptom of rose replant disease (RRD). Currently, limited information is available on the causes and the etiology of RRD compared to apple replant disease (ARD). Thus, this study aimed at analyzing growth characteristics, root morphology, and root metabolites, as well as microbial communities in the rhizosphere of the susceptible rootstock Rosacorymbifera 'Laxa' grown in RRD-affected soil from two sites (Heidgraben and Sangerhausen), either untreated or disinfected by γ-irradiation. In a greenhouse bioassay, plants developed significantly more biomass in the γ-irradiated than in the untreated soils of both sites. Several plant metabolites detected in R. corymbifera 'Laxa' roots were site- and treatment-dependent. Although aloesin was recorded in significantly higher concentrations in untreated than in γ-irradiated soils from Heidgraben, the concentrations of phenylalanine were significantly lower in roots from untreated soil of both sites. Rhizosphere microbial communities of 8-week-old plants were studied by sequencing of 16S rRNA, ITS, and cox gene fragments amplified from total community DNA. Supported by microscopic observations, sequences affiliated to the bacterial genus Streptomyces and the fungal genus Nectria were identified as potential causal agents of RRD in the soils investigated. The relative abundance of oomycetes belonging to the genus Pythiogeton showed a negative correlation to the growth of the plants. Overall, the RRD symptoms, the effects of soil treatments on the composition of the rhizosphere microbial community revealed striking similarities to findings related to ARD.

Microbial changes linked to the accelerated degradation of the herbicide atrazine in a range of temperate soils

Accelerated degradation is the increased breakdown of a pesticide upon its repeated application, which has consequences for the environmental fate of pesticides. The herbicide atrazine was repeatedly applied to soils previously untreated with s-triazines for >5 years. A single application of atrazine, at an agriculturally relevant concentration, was sufficient to induce its rapid dissipation. Soils, with a range of physico-chemical properties and agricultural histories, showed similar degradation kinetics, with the half-life of atrazine decreasing from an average of 25 days after the first application to <2 days after the second. A mathematical model was developed to fit the atrazine-degrading kinetics, which incorporated the exponential growth of atrazine-degrading organisms. Despite the similar rates of degradation, the repertoire of atrazine-degrading genes varied between soils. Only a small portion of the bacterial community had the capacity for atrazine degradation. Overall, the microbial community was not significantly affected by atrazine treatment. One soil, characterised by low pH, did not exhibit accelerated degradation, and atrazine-degrading genes were not detected. Neutralisation of this soil restored accelerated degradation and the atrazine-degrading genes became detectable. This illustrates the potential for accelerated degradation to manifest when conditions become favourable. Additionally, the occurrence of accelerated degradation under agriculturally relevant concentrations supports the consideration of the phenomena in environmental risk assessments.

Fenton's reagent for the rapid and efficient isolation of microplastics from wastewater

Fenton's reagent is a very useful preparation method for the efficient and bias-free analysis of microplastics. The catalytic reaction did not affect microplastics chemistry or size, offering a simple, high-speed and low-cost method for processing microplastics present in wastewater or other complex media.

Differential cytokine responses in human and mouse lymphatic endothelial cells to cytokines in vitro

BACKGROUND

Inflammatory cytokines dysregulate microvascular function, yet how cytokines affect lymphatic endothelial cells (LEC) are unclear.

METHODS AND RESULTS

We examined effects of TNF-α, IL-1 beta, and IFN-gamma on LEC proliferation, endothelial cell adhesion molecule (ECAM) expression, capillary formation, and barrier changes in murine (SV-LEC) and human LECs (HMEC-1a).

RESULTS

All cytokines induced ICAM-1, VCAM-1, MAdCAM-1, and E-selectin in SV-LECs; TNF-α, IL-1 beta; and IFN-gamma induced ECAMs (but not MAdCAM-1) in HMEC-1a. IL-1 beta increased, while IFN-gamma and TNF-α reduced SV-LEC proliferation. While TNF-α induced, IFN-gamma decreased, and IL-1 beta did not show any effect on HMEC-1a proliferation. TNF-α, IL-1 beta, and IFN-gamma each reduced capillary formation in SV-LEC and in HMEC-1a. TNF-α and IL-1 beta reduced barrier in SV-LEC and HMEC-1a; IFN-gamma did not affect SV-LEC barrier, but enhanced HMEC-1a barrier. Inflammatory cytokines alter LEC growth, activation and barrier function in vitro and may disturb lymphatic clearance increasing tissue edema in vivo.

CONCLUSION

Therapies that maintain or restore lymphatic function (including cytokines blockade), may represent important strategies for limiting inflammation.

Phase II study of bevacizumab (B), camptosar (I), high-dose 24-hour continuous intravenous infusion of floxuridine (F) and leucovorin (L) in patients with previously untreated metastatic colon cancer. (B-IFL)

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Background: In a previous study, IFL was used in patients (pt) with untreated metastatic colon cancer and a median overall survival (MOS) of 31 months (m). In the current study we added B to IFL to determine toxicity profiles (TP) and the response rate (RR) to the B-IFL regimen. The primary end-point is MOS Methods: Each cycle involved 6 weeks (wks) of treatment. The treatment cycle consisted of a 90 minute infusion of I (110 mg/m2), followed by a 24 hour infusion of F (120mg/kg) and L (500 mg/m2) on wks 1, 2, 4, 5. Pt received B (7.5mg/kg) over 90 minutes on wks 1 and 4 prior to IFL. No therapy was given on wks 3 and 6. Eligible pt received 2 cycles of B-IFL followed by CT scan. Quality of life data and thymidylate synthase expression in peripheral blood mononuclear cells was monitored Results: 22 pt with a median age of 57 (38–82), 11 males and 11 females were enrolled. Median KPS was 90% (50–100). 8 pt (36%) had bilobar liver disease and involvement of 1 other organ, 6 pt (27%) had bilobar liver disease with involvement of ≥ 2 other organs; 5 pt (23.5%) had bilobar liver disease; 2 pt (9%) had abdominal carcinomatosis; 1 pt (4.5 %) had involvement in one liver lobe. Grade (Gr) 4 toxicity: pulmonary embolus 1 pt (5%) incidental CT finding. Gr 3 occurred in 11 pt (50%); DVT, diarrhea (Drh) 3 pt (14%); fatigue (Ftg), infection, port site thrombosis (Pst), small bowel obstruction 2 pt (9%); wound dehiscence 1pt (5%); Gr 2 and 1: constipation; Drh; Ftg; nausea; neutropenia; Pst; alopecia; anorexia; mucositis. 17 pt remain alive with median follow up of 15 m (2–28). 5 pt have died due to progression of disease. The estimated median time to progression was 13 m with corresponding lower 95% confidence bound of 8.4 m. Kaplan-Meier estimate at 2 yr survival is 61% (95% CI 27–83%). RR in 21 pt was 67% (95% CI: 43–85%). Conclusions: B-IFL regimen has a manageable TP. RR and progression free interval were promising. Pt accrual is ongoing. Supported by Pfizer.

No significant financial relationships to disclose.

DNA-induced structural changes in the papillomavirus capsid

Human papillomavirus capsid assembly requires intercapsomeric disulfide bonds between molecules of the major capsid protein L1. Virions isolated from naturally occurring lesions have a higher degree of cross-linking than virus-like particles (VLPs), which have been generated in eukaryotic expression systems. Here we show that DNA encapsidation into VLPs leads to increased cross-linking between L1 molecules comparable to that seen in virions. A higher trypsin resistance, indicating a tighter association of capsomeres through DNA interaction, accompanies this structural change.

Down-regulation of telomerase activity in malignant lymphomas by radiation and chemotherapeutic agents

The effects of radiation and cytotoxic agents on telomerase activity in lymphoma cells were analyzed by a polymerase chain reaction-based telomeric repeat amplification protocol coupled with an enzyme-linked immunosorbent assay, reverse transcriptase-polymerase chain reaction for the expression of the catalytic subunit of telomerase (hTERT), and by Western blot analysis in three lymphoma cell lines (Jurkat, Raji, CEM-6). Telomeric repeat amplification protocol-enzyme-linked immunosorbent assay demonstrated high basal levels of telomerase activity in all cell lines compared to normal and activated peripheral blood lymphocytes. A significant decrease in telomerase activity was observed in all cell lines after exposure to vincristine for 24 hours. The decrease in telomerase activity paralleled the decrease in cell viability in Jurkat and CEM-6 cells but not in Raji cells. Radiation exposure inhibited the telomerase activity of Jurkat and CEM-6 cells whereas Raji cells were unaffected. Cell cycle analysis demonstrated a significant G(2)/M arrest by cisplatin, VP-16, and vincristine. In contrast to the decline in telomerase activity, the level of hTERT RNA and protein increased. Furthermore, the induction of hTERT was preceded by increased expression of the cyclin-dependent kinase inhibitor, p27/Kip1 protein, and p53. These results indicate that telomerase activity is down-regulated by anti-neoplastic agents in lymphoma cells, however expression of hTERT may not be correlated with telomerase activity. We also show that p27/Kip1 may be involved in the G(2)/M growth arrest induced by anti-neoplastic agents.

Induction of type-specific neutralizing antibodies by capsomeres of human papillomavirus type 33

The immunogenicity of capsomeres of human papillomavirus type 33 was evaluated in a dose-response analysis. Capsomeres were obtained free of capsids by expression of L1 carrying the single point mutation C427S. Neutralizing antibodies were detected using an in vitro pseudoinfection assay. Capsomeres induced type-specific, neutralizing antibodies in mice even in the absence of adjuvant. The neutralization titers of immune sera raised without adjuvant were 10- to 20-fold lower than those of antisera to virus-like particles, but virtually identical using Freund's adjuvant. These data indicate that capsomeres may substitute for virus-like particles in future vaccines when used with an adjuvant appropriate for human vaccination.

Immunological analyses of human papillomavirus capsids

Recombinant human papillomavirus (HPV) virus-like particles (VLPs) are promising vaccine candidates for controlling anogenital HPV disease. Questions remain, however, concerning the extent of capsid antigenic similarity between closely related virus genotypes. To investigate this issue, we produced VLPs and corresponding polyclonal immune sera from several anogenital HPV types, and examined these reagents in enzyme-linked immunosorbent assays (ELISAs) and in cross-neutralization studies. Despite varying degrees of L1 genetic sequence relatedness, VLPs of each type examined induced high-titer serum polyclonal antibody responses that were entirely genotype-specific. In an in vitro infectivity assay, only cognate VLP antisera were able to neutralize pseudovirions of HPV-16, HPV-18 and HPV-33, with two exceptions: HPV-31 and HPV-45 VLP post-immune sera demonstrated low levels of neutralizing activity against pseudovirions of HPV-33 and HPV-18, respectively. In other experiments, epitopes shared between closely related types were found to be less immunogenic than, and antigenically distinct from, primary type-specific B-cell determinants of the viral capsid. In addition, results from epitope blocking experiments suggested a close correlation between primary type-specific capsid antigenic sites and virion neutralization. These findings support the view that papillomavirus genotypes denote unique viral serotypes, and suggest that a successful vaccine for these viruses will likely require the inclusion of VLPs of each serotype for which protection is desired.

Human papillomavirus infection requires cell surface heparan sulfate

Using pseudoinfection of cell lines, we demonstrate that cell surface heparan sulfate is required for infection by human papillomavirus type 16 (HPV-16) and HPV-33 pseudovirions. Pseudoinfection was inhibited by heparin but not dermatan or chondroitin sulfate, reduced by reducing the level of surface sulfation, and abolished by heparinase treatment. Carboxy-terminally deleted HPV-33 virus-like particles still bound efficiently to heparin. The kinetics of postattachment neutralization by antiserum or heparin indicated that pseudovirions were shifted on the cell surface from a heparin-sensitive into a heparin-resistant mode of binding, possibly involving a secondary receptor. Alpha-6 integrin is not a receptor for HPV-33 pseudoinfection.

EBV-associated perianal Hodgkin's disease in an HIV-positive individual

Hodgkin's disease (HD) has a higher incidence in HIV-positive individuals. It tends to occur at extranodal sites, frequently exhibits an unfavorable histological type with large numbers of neoplastic cells, and almost invariably harbors Epstein-Barr Virus (EBV). We describe a case of a 33-year-old HIV-positive man who presented with anal pain from a 4-cm mass in the anorectal canal. He had no B symptoms or peripheral lymphadenopathy. A chest X-ray was within normal limits. A biopsy showed an ulcerated mass composed of a mixed infiltrate of lymphocytes, plasma cells, eosinophils, and Reed-Sternberg (RS) cells positive for CD15 and strongly positive for CD30. They were negative for CD45 and CD20. Numerous RS cells and lymphocytes were positive for EBV RNA using the EBER-1 probe. This highly unusual presentation of HD may reflect the greater incidence of anorectal lymphoma and of extranodal HD in the HIV-positive population.

Primary Hodgkin's disease of the CNS in an immunocompetent patient: a case study and review of the literature

Primary Hodgkin's disease limited to the CNS is exceedingly rare. Little is known regarding etiologic risk factors, optimal management, and prognosis. A case of Hodgkin's disease confined to the CNS, with cerebrospinal fluid negative for cytology, is described in an immunocompetent patient previously treated for hyperthyroidism with 131I. The patient underwent craniotomy, with resection of two lesions in close proximity within the parenchyma of the temporoparietal lobe. Histopathology revealed classic nodular sclerosing Hodgkin's disease, without evidence of Epstein-Barr viral infection. Treatment included radiation to the whole brain with a boost to the tumor bed. The patient made a full neurologic recovery and remains free of disease recurrence 21 months after treatment. A literature review has identified only 9 additional cases. Seven of 8 evaluable patients remain alive and free of recurrence with a median follow-up of 13 months. The risk factors for this presentation remain undefined. Although follow-up is short, radiotherapy alone appears to provide excellent disease-free survival. Chemotherapy may be reserved for patients with positive cerebrospinal fluid, extracranial disease, or subsequent relapse.

Rapid generation of broad T-cell immunity in humans after a single injection of mature dendritic cells

Dendritic cells (DCs) are potent antigen-presenting cells that initiate protective T-cell immunity in mice. To study the immunogenicity of DCs in humans, we injected 9 healthy subjects subcutaneously with a control injection of autologous monocyte-derived, mature DCs, followed 4-6 weeks later by DCs pulsed with keyhole limpet hemocyanin (KLH), HLA-A*0201-positive restricted influenza matrix peptide (MP), and tetanus toxoid (TT). Four more subjects received these antigens without DCs. Injection of unpulsed DCs, or antigens alone, failed to immunize. Priming of CD4(+) T cells to KLH was observed in all 9 subjects injected with KLH-pulsed DCs, and boosting of TT-specific T-cell immunity was seen in 5 of 6 subjects injected with TT-pulsed DCs. Injection of antigen-pulsed DCs led to a severalfold increase in freshly isolated MP-specific, IFN-gamma-secreting CD8(+) T cells in all 6 HLA-A*0201-positive subjects, as early as 7 days after injection. When T cells were boosted in culture, there was an increase in MHC tetramer-binding cells and cytotoxic T cells after DC vaccination. These data provide the first controlled evidence of the immunogenicity of DCs in humans, and demonstrate that a single injection of mature DCs rapidly expands T-cell immunity.

Dendritic cells generated from blood monocytes of HIV-1 patients are not infected and act as competent antigen presenting cells eliciting potent T-cell responses

The CTL response to HIV-I can be vigorous, but antigen presenting cell requirements have not been studied in detail. To approach this question, we have examined the dendritic cell populations that can be obtained from the blood of HIV-1 infected individuals. We studied 13 asymptomatic patients, who spanned a wide range of plasma viremia and CD4 counts. We show here that sizeable numbers of mature dendritic cells can be generated from nonproliferating progenitors in the blood of HIV + patients using a recently developed approach. The procedure involves two steps. The first step or 'priming' phase is a 7 day culture of T-cell depleted mononuclear cells in medium supplemented with GM-CSF and IL-4. The second step or 'differentiation' phase requires the exposure to monocyte conditioned medium. The yields of DCs from HIV + individuals were comparable to normal blood donors, 0.4 - 3 x 10(6) mature dendritic cells from 50 ml of blood. Strong APC function was evident for both the proliferation of allogeneic T-cells in the MLR, and the generation by syngeneic T-cells of class I restricted, CTL responses to influenza virus. A panel of dendritic cell restricted markers are expressed, including CD83, p55, and perinuclear CD68. By semi-quantitative PCR analysis, the cytokine derived cells did not express HIV-1 DNA. We suggest that these blood derived dendritic cells will be effective for studies of immune responses to HIV-1 antigens and may be considered as adjuvants for active immunotherapy.

A survey of seroprevalence of human papillomavirus types 16, 18 and 33 among children

The importance and natural history of HPV infections in childhood is incompletely understood. We performed a survey for presence of serum antibodies to HPV capsids among 1031 children aged 0 to 13 years, resident in Stockholm, Sweden. The HPV seroprevalence among these children was 3.0% for HPV16, 0.6% for HPV18 and 2.7% for HPV33. By comparison, among simultaneously analyzed positive control panels comprising women with CIN or healthy women with type-specific cervical HPV DNA, seroprevalence of HPV 16, 18 and 33 was 69%, 58% and 63% respectively. The results suggest that HPV infection in childhood is not common.

Sexual behaviour and papillomavirus exposure in cervical intraepithelial neoplasia: a population-based case-control study

Sexual history is an established risk determinant for cervical neoplasia. It is not clear if human papillomavirus (HPV) exposure entirely explains the sexual behaviour-related risk or if other sexually transmitted agents may act as cofactors for HPV in carcinogenesis. The aim of this study was to elucidate whether HPV exposure or HPV persistence explains the sexual history-related risk of high-grade cervical intraepithelial neoplasia (CIN) using a population-based case-control study of most of the 254 women referred to colposcopy in the Vasterbotten county in Sweden because of an abnormal cervical smear during October 1993 to December 1995 and 320 age-matched women from the general population. The women were interviewed for sexual history and tested for presence of serum antibodies to HPV-16, -18 and -33 as well as for presence of HPV DNA in cervical brush samples. HPV-16, -18 and -33 seropositivity was specific for the corresponding type of HPV DNA, dependent on the lifetime sexual history and associated with a two- to threefold increased risk of CIN 3. There was no sexual history-related risk of CIN among HPV-seropositive women and adjustment for HPV DNA presence explained the sexual history-related risk of CIN. In conclusion, HPV exposure appeared to explain the sexual history-related risk of high-grade CIN.

Prospective study on cervical neoplasia IV. Presence of HPV antibodies

Sera collected in the course of a prospective study carried out in Prague in 1975-1983 were assayed for the presence of human papillomavirus (HPV) antibodies. Women with cervical neoplasia proven by biopsy at enrollment possessed antibodies to peptides derived from E2, E4 and E7 proteins of HPV16 and to virus-like particles (VLPs) of HPV16, -18 and -33 significantly more frequently than matched controls. Women without cervical neoplasia at enrollment who developed the disease in the course of the study differed from matched controls by a higher prevalence of antibodies against VLPs of HPV16 and -18 but not against early antigens of HPV16. In 19 of the latter subjects, paired serum specimens were tested, the first samples having been taken at enrollment and the second at diagnosis. Development of the disease was associated with seroconversion from negativity to positivity to at least one HPV antigen in 11 (57.9%) women.

cDNA cloning, in vitro expression, and biochemical characterization of cholinesterase 1 and cholinesterase 2 from amphioxus--comparison with cholinesterase 1 and cholinesterase 2 produced in vivo

We have isolated cDNAs coding for the complete amino acid sequences of cholinesterase 1 (ChE1) and cholinesterase 2 (ChE2) from amphioxus. Both ChE transcripts have the characteristics of H-type catalytic subunits, which are inserted in the membrane via an ethanolamine-glycan-phosphatidylinositol anchor. The members of the catalytic triad of ChEs, the three pairs of cysteine residues involved in intrachain disulfide bonding, a cysteine near the carboxy terminal of both sequences, which could mediate interchain disulfide bonding, and 11 of the 14 aromatic amino acids that line the catalytic gorge of AChE are conserved. A remarkable difference between the two enzymes is in the region of the acyl-binding pocket, which plays an important role in determining substrate specificity in cholinesterases. ChE2 contains a sequence that resembles the acyl pocket of invertebrate ChE, while the acyl-binding site of ChE1 is novel. There are also differences between the two enzymes in the peripheral anionic site, which mediates inhibition by certain ligands. In vitro expression in COS-7 cells demonstrates that ChE2 hydrolyzes acetylthiocholine almost exclusively, while ChE1 hydrolyzes both acetylthiocholine and butyrylthiocholine. Both enzymes are inhibited comparably by BW284c51, but ChE1 is considerably more resistant to inhibition by propidium, ethopropazine, and eserine than is ChE2. Velocity sedimentation indicates that ChE1 and ChE2 are present as amphiphilic and nonamphiphilic G2 forms in vivo and in vitro. Another molecular form, which sediments at 17 S, is also present in vivo. Nondenaturing gel electrophoresis in conjunction with digestion by phosphatidylinositol-specific phospholipase C demonstrates that the vast majority of ChE1 and ChE2 is present as ethanolamine-glycan-phosphatidylinositol-anchored G2 forms in vivo. ChE1 also possesses an ethanolamine-glycan-phosphatidylinositol-anchor in vitro; however, ChE2 produced in vitro could not be detected on nondenaturing gels.

Prevalence of antibodies to human papillomaviruses in the general population of the Czech Republic

Sera from 450 individuals between the age of 1 and 80 years, representing the general population of the Czech Republic, were tested for the presence of antibodies to human-papillomavirus(HPV)-derived antigens. The following antigens were used: (i) HPV1 virions; (ii) HPV16, -18 and -33-virus-like particles (VLP); (iii) peptides derived from L2 open reading frames (ORFs) of HPV16 and HPV6/11; (iv) peptides derived from HPV16 E2, E4 and E7 ORFs of HPV16. The prevalence of antibodies reactive with the capsid-derived antigens was age-dependent, while no clear age dependence was observed in the distribution of antibodies to peptides derived from HPV16 early proteins. In individual sera, high correlations between the presence of antibodies reactive with the 2 L2 peptides, also between the antibodies reactive with different VLPs, were found. While the simultaneous presence of the 2 L2 antibodies was frequently detected in individual sera in all age groups, the simultaneous occurrence of VLP antibodies was detected mostly in subjects older than 20 years. There were no significant differences in HPV-antibody distribution between men and women.

Papillomavirus assembly requires trimerization of the major capsid protein by disulfides between two highly conserved cysteines

We have used viruslike particles (VLPs) of human papillomaviruses to study the structure and assembly of the viral capsid. We demonstrate that mutation of either of two highly conserved cysteines of the major capsid protein L1 to serine completely prevents the assembly of VLPs but not of capsomers, whereas mutation of all other cysteines leaves VLP assembly unaffected. These two cysteines form intercapsomeric disulfides yielding an L1 trimer. Trimerization comprises about half of the L1 molecules in VLPs but all L1 molecules in complete virions. We suggest that trimerization of L1 is indispensable for the stabilization of intercapsomeric contacts in papillomavirus capsids.

Sero-epidemiological association between human-papillomavirus infection and risk of prostate cancer

Some epidemiological studies of prostate cancer have suggested the existence of a sexually transmitted risk factor, and some studies have reported the presence of human papillomavirus (HPV) DNA in prostate-cancer tissue. To perform a sero-epidemiological evaluation of whether HPV infection is associated with increased risk for prostate cancer, we performed a nested case-control study within a serum bank containing samples from 20,243 healthy Finnish men. We identified 165 cases of prostate cancer that were diagnosed up to 24 years after donation of the serum sample. Two control subjects per case were selected, matched for gender, age and municipality of residence. Serum samples were analyzed for the presence of IgG antibodies against 4 HPV types and against Chlamydia. The presence of antibodies against HPV type 18 was associated with a 2.6-fold increased risk of developing prostate cancer during follow-up (p < 0.005). HPV type 16 tended to be associated with subsequent prostate-cancer occurrence (relative risk: 2.4, p = 0.06), whereas seropositivity for HPV type 11 or type 33 or for Chlamydia was not associated with risk. The results suggest that infection with oncogenic HPV might be involved in the etiology of a minority of prostate cancers.

Utilizing the PK scale of the MMPI-2 to detect posttraumatic stress disorder in college students

This study investigated the utility of the PK scale of the MMPI-2 with college students. Results indicated that the PK scale, when combined with DSM IV criteria, does discriminate between college students who obtain a score of 65 or higher and those who score below 65.

Order effect for two measures of hypnotizability

Mean scores of students on the Harvard Group Scale of Hypnotic Susceptibility, Form A and the Creative Imagination Scale were higher if the latter preceded the former ( n = 15); in contrast, in the reverse order ( n = 20) scores on both tests were lower.

A monocyte conditioned medium is more effective than defined cytokines in mediating the terminal maturation of human dendritic cells

Mature human dendritic cells can be generated in substantial numbers from nonproliferating progenitors in human blood using a two-step protocol. T cell-depleted mononuclear cells are first cultured with granulocyte-macrophage colony-stimulating factor and interleukin-4 (IL-4) and then exposed to monocyte conditioned medium (MCM). The dendritic cells generated using this approach are rendered terminally mature and are the most potent antigen presenting cells identified to date in humans. We sought to characterize factors in MCM that induce the terminal differentiation of dendritic cells. MCM contained substantial, although varying, quantities of several factors including tumor necrosis factor-alpha, IL-1beta, IL-6, and interferon-alpha. However, none of the four factors, individually or in various combinations, could fully substitute for the MCM to generate irreversibly differentiated dendritic cells. The yields, percentage of cells expressing the mature phase marker CD83, and mixed leukocyte reaction-stimulatory function were lower when defined cytokines were used in the place of MCM. Therefore, the full maturation of dendritic cells, because it entails changes in many known cell and molecular properties, requires a number of different cytokines that are released in tandem from appropriately stimulated monocytes. We propose that MCM-matured dendritic cells will be the most effective adjuvants for immunotherapy in vivo.

A prospective, seroepidemiological study of the role of human papillomavirus in esophageal cancer in Norway

Infection with the human papillomavirus (HPV), notably HPV type 16, has been associated with esophageal cancer in seroepidemiological studies. To evaluate the consistency of the association, we performed a nested case-control study of HPV seropositivity and risk of esophageal cancer within a prospectively followed cohort of 300,000 Norwegian men and women who had donated blood samples to a serum bank. The data file of the serum bank was linked with the nationwide Cancer Registry of Norway to identify esophageal cancers diagnosed after donation of the serum sample. Fifty-seven cases and 171 matched controls were analyzed for antibodies to specific microorganisms, and odds ratios for developing esophageal cancer were calculated. There was an increased risk of developing esophageal cancer among HPV 16-seropositive subjects (odds ratio = 6.6; 95% confidence interval, 1.1-71) but not among Chlamydia trachomatis-seropositive subjects. Adjustment for the presence of serum cotinine, a marker of smoking habits, did not affect the estimates substantially. The seroepidemiological association between HPV 16 and esophageal cancer seems to be consistent in different countries.

Prospective seroepidemiological study of role of human papillomavirus in non-cervical anogenital cancers

OBJECTIVE

To evaluate the association between infection with the major oncogenic types of human papillomavirus and the risk of developing non-cervical anogenital cancers in a cohort followed up prospectively.

DESIGN

Data from two large serum banks to which about 700,000 people had donated serum samples were followed up for a mean of 8 years. People who developed non-cervical anogenital cancers during follow up were identified by registry linkage with the nationwide cancer registries in Finland and Norway. Within this cohort a nested case-control study was conducted based on the serological diagnosis of infection with human papillomavirus types 16, 18, and 33.

SUBJECTS

81 cases and 240 controls matched for sex, age, and storage time of serum samples.

MAIN OUTCOME MEASURES

Odds ratios of developing non-cervical anogenital cancers in presence of IgG antibodies to specific micro-organisms.

RESULTS

Subjects seropositive for human papillomavirus type 16 had an increased risk of developing non-cervical anogenital cancers (odds ratio 3.1 (95% confidence interval 1.4 to 6.9)). Subjects seropositive for type 33 also had an increased risk (odds ratio 2.8 (1.0 to 8.3)) but not significantly after adjustment for infection with type 16. Seropositivity for human papillomavirus type 16 was associated with an increased risk of developing vulvar and vaginal cancers (odds ratio 4.5 (1.1 to 22)) and a strongly increased risk of developing preinvasive vulvar and vaginal lesions (odds ratio infinity (3.8 to infinity)). Seropositivity for human papillomavirus type 18 increased the risk of developing preinvasive lesions (odds ratio 12 (1.2 to 590)). High, but non-significant odds ratios for types 16 and 33 were seen for penile cancers.

CONCLUSIONS

This study provides prospective seroepidemiological evidence that infection with human papillomavirus type 16 confers an increased risk of developing non-cervical genital cancers, particularly vulvar and vaginal cancers.

Prospective seroepidemiologic study of human papillomavirus infection as a risk factor for invasive cervical cancer

BACKGROUND

Major risk factors for invasive cervical cancer include infection with human papillomavirus (HPV), infection with other sexually transmitted pathogens (e.g., Chlamydia trachomatis), and smoking. Since exposures to these risk factors can be related, the contribution of any single factor to cervical carcinogenesis has been difficult to assess. We conducted a prospective study to define the role of HPV infection in cervical carcinogenesis, with invasive cancer as an end point.

METHODS

A nested case-control study within a joint cohort of 700,000 Nordic subjects was performed. The 182 women who developed invasive cervical cancer during a mean follow-up of 5 years were matched with 538 control women on the basis of age and time of enrollment. Serum samples taken at enrollment were analyzed for evidence of tobacco use (i.e., cotinine levels); for antibodies against HPV types 16, 18, and 33; and for antibodies against C. trachomatis. Relative risks (RRs) were estimated by use of conditional logistic regression.

RESULTS

Presence of antibodies against HPV in serum (seropositivity) was associated with an increased risk of cervical cancer, and adjustment for smoking and for C. trachomatis seropositivity did not affect this finding (RR = 2.4; 95% confidence interval [CI] = 1.6-3.7). HPV16 seropositivity was associated primarily with an increased risk of squamous cell carcinoma (RR = 3.2; 95% CI = 1.7-6.2). In contrast, risk associated with HPV18 seropositivity tended to be higher for cervical adenocarcinoma (RR = 3.4; 95% CI = 0.8-14.9). In populations with a low prevalence of antibodies against C. trachomatis, the HPV16-associated risk of cervical cancer was very high (RR = 11.8; 95% CI = 3.7-37.0); in contrast, in populations with a high prevalence of antibodies against C. trachomatis, no excess risk was found.

CONCLUSION

Past infection with HPV16 increases the risk of invasive cervical squamous cell carcinoma, most clearly seen in populations with a low prevalence of sexually transmitted diseases.

Human papillomavirus antibody responses among patients with incident cervical carcinoma

The human papillomavirus (HPV) is recognized as a major cause of cervical cancer precursor lesions. HPV serology is a key method in the continuing elucidation of the importance of HPV exposure for cancer development and in predicting HPV-associated diseases. To extend previous HPV serological studies on cervical cancer, serum samples from a consecutive series of 216 women with incident untreated cervical carcinoma and 243 age- and sex-matched healthy blood donors were evaluated for the presence of antibodies against HPV capsids, a marker of past or present HPV exposure, as well as against several cervical cancer-associated defined HPV epitopes. Among the capsid antibody responses, HPV type 16 seropositivity had the strongest association with cervical cancer (OR 2.7, 95% CI 1.8-4.2), but HPV 18 and HPV 33 seropositivities were also significantly associated with cervical cancer (OR 1.6, 95% CI 1.1-2.5; and OR 1.5, 95% CI 1.0-2.2, respectively). The antibody responses against the defined HPV epitopes were confirmed to be associated with cervical cancer, at ORs ranging from 1.4 to 2.0. In conclusion, the study confirms that antibodies against defined HPV epitopes are associated with cervical cancer and provides evidence that seropositivities for HPV types 16, 18, and 33 are associated with cervical cancer risk.

Adrenal histoplasmosis: diagnosis by fine-needle aspiration biopsy

A 54-year-old man presented with a 6-month history of fever, night sweats, and weight loss. He had hepatosplenomegaly, and bilateral adrenal masses were discovered on computed tomographic (CT) scan. CT-guided fine-needle aspiration biopsy (FNAB) of the right adrenal mass demonstrated purulent material. Special stains done on this material showed organisms with morphologic features of Histoplasma capsulatum. The patient was started on antifungal therapy and discharged. FNAB of the adrenal gland is an effective method in the diagnosis of unusual infectious diseases. Special stains for micro-organisms proved helpful in the initial diagnosis of histoplasmosis.

Generation and neutralization of pseudovirions of human papillomavirus type 33

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.

Characterization of the DNA-binding activity of the E1 and E2 proteins and the E1/E2 complex of human papillomavirus type 33

The E1 and E2 proteins of papillomaviruses are essential for the initiation of viral DNA replication. We have purified the E2 protein of human papillomavirus type 33 (HPV-33) by immunoaffinity chromatography. The purified E2 protein bound with high affinity to all four consensus binding sites of HPV-33 (Kd approximately equal to 2 x 10(-10)M). A putative E2 binding site differing at one position in the second stem of the palindrome was not bound by E2. The E1 protein of HPV-33 purified by affinity chromatography using glutathione S-transferase as tag displayed specific DNA-binding activity in footprint analyses protecting HPV-33 nucleotides 7896 to 7909/1 to 18 from DNasel digestion. Hypersensitive sites at position 6 on the sense and position 1 on the antisense strand were observed in the middle of the protected region. An E1/E2 complex protected the E1 binding site and E2 binding sites from DNasel digestion suggesting that both proteins retain DNA-binding activity in the complex.

Correlation between the presence of anti HPV33 VLP antibodies and HPV DNA in cervical neoplasia patients

The L1 capsid proteins derived from human papillomavirus (HPV) type 33 were expressed in a recombinant baculovirus system using Sf9 insect cells. Selected sera originating in women from case-control study carried out in Spain and Colombia found negative and positive for HPV16, 18, 31, 33 and 35 DNA were tested in ELISA for the presence of IgG antibodies to purified virus-like particles (VLP). The reactivity was type-restricted with the possible exception of HPV31.

Dendritic cells as immunogens for human CTL responses

The cellular requirements for generating potent human CD8+ CTLs to influenza A virus in vitro have been defined. Furthermore, we have developed improved methods for generating large numbers of DCs from non-proliferating progenitors. These developments have enabled the design of new strategies to elicit CTLs in vivo. For example, together with IL-12, antigen-pulsed DCs may be a useful approach for boosting CTL responses against infectious agents and malignancies. Our results also reopen the potential use of inactivated virus preparations as immunogens for CTL responses.

Cervical mucus antibodies against human papillomavirus type 16, 18, and 33 capsids in relation to presence of viral DNA

To investigate whether cervical mucus antibodies against human papillomavirus (HPV) capsids are associated with the detection of HPV DNA or HPV-related cytological diagnoses, 611 samples of cervical secretions from 359 women referred to a colposcopy clinic were tested by an enzyme-linked immunosorbent assay for the presence of immunoglobulin A (IgA) antibodies against HPV capsids of HPV type 16, 18, or 33 and for the presence of cervical HPV DNA by PCR. Among subjects with at least one cervical sample positive for HPV type 16 (HPV-16) DNA, 28.1% also had at least one HPV-16 IgA-positive cervical sample (odds ratio [OR] = 2.9; P = 0.0003). IgA to HPV-18 was also more common among HPV-18 DNA-positive subjects (OR = 3.1; P = 0.0325) and IgA to HPV-33 was more common among HPV-33 DNA-positive subjects (OR = 4.2; P = 0.0023). Cervical IgA antibodies to HPV-16 were also more common among patients with cervical intraepithelial neoplasia, particularly among patients with cervical intraepithelial neoplasia grade I (P < 0.0005). The data indicate that an HPV type-restricted IgA antibody response against HPV capsids is detectable in cervical mucus and is associated with a concomitant cervical HPV infection.

Improved methods for the generation of dendritic cells from nonproliferating progenitors in human blood

We have investigated an improved method for generating sizable numbers of mature dendritic cells from nonproliferating progenitors in human blood. The procedure uses 1% human plasma in the place of 10% fetal calf serum and involves two steps. The first step or 'priming' phase is a 6-7 day culture of T cell depleted mononuclear cells in medium supplemented with GM-CSF and IL-4. The second step or 'differentiation' phase requires the exposure to macrophage conditioned medium. This medium cannot be replaced by several known cytokines such as TNF-alpha, IL-1, IL-6, IL-12 and IL-15, and cannot be inhibited with neutralizing antibodies to IL-1, TNF-alpha, IL-6 or IL-12 alone, or in combination. Using this two-step approach, we obtain substantial yields. About 1-3 x 10(6) mature dendritic cells are generated from 40 ml of blood vs. < 0.1 x 10(6) from noncytokine treated blood. The dendritic cells derive from progenitors found primarily in a radioresistant population of CD14+ and adherent blood mononuclear cells and have all the features of mature cells. They include a stellate cell shape, nonadherence to plastic, and very strong T cell stimulatory activity. Strong APC function was evident for both the proliferation of allogeneic T cells in the MLR, and the generation by syngeneic T cells of class I restricted, CTL responses to influenza virus. A panel of dendritic cell restricted markers is also expressed, including CD83, p55, and perinuclear CD68. All of these dendritic cell properties are retained for at least 3 days when the cytokines are removed, suggesting that these populations are stable and terminally differentiated. We suggest that these cells will be effective in vivo as adjuvants for active immunotherapy.

A prospective study on the risk of cervical intra-epithelial neoplasia among healthy subjects with serum antibodies to HPV compared with HPV DNA in cervical smears

To estimate the risk of developing cervical intra-epithelial neoplasia (CIN) among women exposed to human papillomavirus (HPV) type 16, we performed a prospective study in a population-based cohort of more than 15,000 women followed for 34.9 months. Seventy-four women developed CIN during follow-up and were matched for age, time of sampling and area of residence with 148 women who remained CIN-free during follow-up. The blood samples taken at enrollment were tested for serum antibodies to HPV types 16, 18 and 33 capsids. Cervical smears or biopsies were analyzed for the presence of HPV DNA by nested PCR using HPV general primers and by HPV 16- and 18-type-specific PCR HPV serology and HPV-PCR were in good agreement, particularly when the blood sample and the Pap smear were taken less than 6 months apart. HPV DNA was found in 88% of cases and 4% of controls, whereas HPV 16 DNA was present in 44% of cases and in 1 of 142 controls. HPV-16-seropositive women had a 3-fold increased risk of developing CIN. The risk was highest among women younger than 35 years of age, of whom an estimated 3.4% of HPV-16-seropositive and 0.5% of seronegative women developed CIN. Since the risk associated with HPV-16 seropositivity (a measure of past or present infection) was 35-fold lower than that of HPV DNA (present infection), most infections appear to be eliminated before CIN develops. In conclusion, HPV 16 infection does confer an excess risk of CIN development, and HPV DNA detection has a high predictive value for the presence of high-grade CIN.

Seropositivities to human papillomavirus types 16, 18, or 33 capsids and to Chlamydia trachomatis are markers of sexual behavior

The association of seropositivity to human papillomavirus (HPV) capsids of types 11, 16, 18, or 33 with sexual behavior was investigated. Among 1002 women visiting family planning or youth clinics in Sweden, an age-matched subsample of 274 women stratified according to lifetime number of sex partners was analyzed. The proportion of HPV-16-seropositive subjects increased linearly at approximately 4% per partner (P < .001), from 4% among those with 1 lifetime partner to 35% among those with >5 lifetime partners. Also, HPV-33 and HPV-18 seroprevalences were linearly dependent on the number of partners (P < .001, increase with 4% per partner, and P = .008, increase with approximately 3% per partner, respectively), providing serologic confirmation that the important mode of transmission of HPV-16, -18, or -33 infection in women is sexual. HPV serology appears to be suitable as a marker of sexual behavior in populations.

Domains of the E1 protein of human papillomavirus type 33 involved in binding to the E2 protein

Papillomavirus E1 and E2 proteins are essential for the initiation of viral DNA replication. We have now analyzed the interaction of E1 and E2 of human papillomavirus type 33, which is associated with cervical carcinoma. When synthesized in insect cells using the baculovirus expression system, the E1 and E2 proteins interacted efficiently at 4 degree. A monoclonal antibody recognizing E1 amino acids 584--600 inhibited the binding of E2 and vice versa, indicating that these amino acids are involved in E2 binding. To confirm this result, a mutational analysis of E1 was performed. The E2 binding activity of E1 deletion and point mutant proteins was assayed using glutathione S-transferase E1 fusion proteins and in vitro translated proteins. At 4 degree, the C-terminal portion of E1 including amino acids 312--644 was sufficient for E2 binding. Introduction of C-terminal deletions or a point mutation at position 586 (Pro --> Glu) resulted in the loss of the E2 binding activity. A second more N-terminally located binding domain (E1 amino acids 312--450) became active when the assays were performed at 22 degrees. The monoclonal antibody still inhibited E2 binding at this temperature, indicating that both E2 binding domains are engaged in the context of the full-length protein.

Comparison of development of serum antibodies to HPV16 and HPV33 and acquisition of cervical HPV DNA among sexually experienced and virginal young girls. A longitudinal cohort study

OBJECTIVES

To study the importance of sexual activity and early coitus debut on the risk for acquiring infection with human papillomavirus (HPV) type 16 or 33.

STUDY DESIGN

Ninety-eight healthy adolescent girls were followed up with consecutive interviews and donations of serum and cervical brush samples during 2 years.

RESULTS

Fourteen percent of sexually experienced girls had serum immunoglobulin G to HPV16 and/or HPV33 capsids, and 14% also had cervical HPV16 or HPV33 DNA. Seropositivity for HPV correlated with detection of cervical HPV DNA. None of the 36 girls without coital experience was seropositive or harbored cervical HPV DNA. Seropositivity for HPV was correlated strongly with the number of sexual partners: Odds ratio for > 1 sexual partner was 16.3 (P < 0.001), and for early coitus debut (younger than 17 years of age), it was 14.3 (P < 0.002).

CONCLUSIONS

Both HPV serology and HPV DNA testing indicated that the number of sexual partners and earliness of coitus debut determined the risk for acquiring HPV infection and that nonsexually transmitted infections are rare or nonexistent among adolescent girls.

Synthesis, properties and applications of papillomavirus-like particles

Papillomavirus-like particles can be obtained by expression of the major capsid protein L1 alone or by coexpression with the minor capsid protein L2 in various systems. Virus-like particles (VPLs) and virions have very similar capsid structures. Immunization with VLPs yields antibodies neutralizing virions in vitro. Vaccination of animals with VLPs has been shown to protect against viral challenge. VLPs of human papillomavirus (HPV) are therefore the most promising vaccine candidate to prevent infections with HPVs associated with cervical cancer, the most frequent carcinoma in women worldwide.

Conformational and linear epitopes on virus-like particles of human papillomavirus type 33 identified by monoclonal antibodies to the minor capsid protein L2

The organization of epitopes on the minor capsid protein L2 of human papillomavirus (HPV) type 33 has been analysed using three monoclonal antibodies (MAbs) generated against a large fragment of the L2 protein (amino acids 82-259) expressed as a glutathione S-transferase fusion protein. The topology of the L2 epitopes has been investigated with respect to the structure of HPV-33 virus-like particles (VLPs). Two of the MAbs reacted with linear epitopes which were mapped to amino acids 153-160 and 163-170, respectively. These epitopes were accessible in denatured but not in native VLPs consisting of L1 and L2, suggesting an internal location. The third antibody was unable to detect denatured L2 protein but reacted with native VLPs. This is the first demonstration of an apparent conformational epitope of the HPV L2 protein. A model for the putative orientation of L2 in the papillomavirus capsid is deduced from the location of these and other antigenic sites.

Organization of the major and minor capsid proteins in human papillomavirus type 33 virus-like particles

The organization of the major (L1) and minor (L2) proteins in the human papillomavirus capsid is still largely unknown. In this study we analysed the disulphide bonding between L1 proteins and the association of L2 proteins with capsomers using virus-like particles obtained in insect cells by co-expression of the L1 and L2 genes of human papillomavirus type 33. About 50% of the L1 protein molecules in these particles (1.29 g/cm3) formed disulphide-bonded trimers. Reduction of the intermolecular disulphide bonds by dithiotreitol (DTT) treatment caused disassembly of virus-like particles into capsomers. This indicates that disulphide bonds between capsomers at the threefold symmetry positions of the capsid are essential for the assembly of the papillomavirus capsid. In contrast, the L2 protein was not engaged in intermolecular disulphide bonding. The L2 protein remained associated with capsomers on disassembly by treatment with DTT. When the disassembly was carried out in 0.65 M-NaCl, complete L2 protein molecules bound preferentially to capsomer oligomers, whereas truncated L2 protein molecules bound only to monomers. In 0.15 M-NaCl only complete L2 protein molecules remained bound to capsomers. This indicates that different regions of the L2 protein molecule are differentially involved in the association of the papillomavirus capsid.

Binding and internalization of human papillomavirus type 33 virus-like particles by eukaryotic cells

Infection of cells by human papillomaviruses (HPVs) associated with malignant genital lesions has not been studied because of the lack of an in vitro system and the unavailability of virions. We have now used virus-like particles (VLPs) of HPV type 33 to analyze the initial events in the interaction of the HPV capsid with cell lines. Binding of VLPs to HeLa cells was observed in biochemical assays and by immunofluorescence. VLP binding was inhibited by antisera raised against VLPs but not by monoclonal antibodies recognizing either L1 or L2 epitopes accessible on VLPs. Under saturating conditions, approximately 2 x 10(4) VLPs were bound per cell, with a dissociation constant of about 100 pM. VLPs composed of L1 alone bound as well as VLPs composed of both capsid proteins, indicating that L2 is not required for initial binding. VLPs dissociated into capsomers did not bind, demonstrating that intercapsomer contacts are required. Neither capsomers nor simian virus 40 virions competed with VLP binding. Uptake of VLPs by small and smooth endocytic vesicles was demonstrated by immunoelectron microscopy. Cellular binding of VLPs was sensitive to trypsin but not to sialidase, N-glycosidase, or octyl-beta-D-glycopyranoside treatment, suggesting that a cell surface protein is involved in the VLP binding. Cell lines originating from a variety of tissues and organisms as distantly related as insects and humans bound VLPs with similar efficiency and specificity. Therefore, the putative receptor mediating VLP attachment should be highly conserved and cannot be responsible for the species and tissue specificity of HPVs.

Analysis of type-restricted and cross-reactive epitopes on virus-like particles of human papillomavirus type 33 and in infected tissues using monoclonal antibodies to the major capsid protein

A panel of six monoclonal antibodies recognizing at least three different antigenic regions has been raised against the L1 major capsid protein of human papillomavirus type 33 (HPV-33), which is associated with cervical carcinoma. The antigenic sites defined by these antibodies have been mapped and classified as type-restricted or broadly cross-reactive using bacterially expressed L1 fusion proteins of a variety of HPV types. Conformational and linear epitopes have been distinguished using native and denatured virus-like particles. HPV infection of genital lesions has been analysed using both monoclonal antibodies and DNA amplification by PCR. The antibodies obtained should be useful to probe the structure of HPV capsids and to develop a general assay for the detection and classification of productive HPV infections.

Assembly of the major and the minor capsid protein of human papillomavirus type 33 into virus-like particles and tubular structures in insect cells

Native virions of human papillomaviruses (HPV) can be isolated from genital lesions only in very limited amounts. Recent studies have shown that virus-like particles can be obtained by expression of the capsid proteins using vaccinia virus recombinants or the baculovirus system. We now present the first detailed characterization of virus-like particles of a human papillomavirus associated with malignant genital lesions, HPV-33, produced in high yield using the baculovirus expression system. Assembly of the major capsid protein L1 alone or together with the minor capsid protein L2 has been obtained. Both spherical virus-like particles of 50-60 nm diameter and tubular structures of either 25-30 nm or 50-60 nm diameter and variable length were extracted from nuclei of the infected insect cells. However, predominantly 50- to 60-nm spherical particles were found in the cell culture medium in long-term infections. The particles have icosahedral symmetry and a density of 1.29 g/cm3 in cesium chloride corresponding to empty papillomavirus capsids. Immunoelectron microscopy confirmed the presence of L1 and L2 in the virus-like particles. The L2 protein seemed to be modified and was shown to be tightly associated with L1 using density gradient and sedimentation analysis. Approximately 50% of the L1 molecules are cross-linked by intermolecular disulfide bonds. This is the first example for the production of HPV-like particles containing both the major and the minor capsid protein using the baculovirus expression system.

Development of type-specific and cross-reactive serological probes for the minor capsid protein of human papillomavirus type 33

Human papillomavirus type 33 (HPV33) is associated with malignant tumors of the cervix. In an attempt to develop immunological probes for HPV33 infections, antisera against various bacterial fusion proteins carrying sequences of the minor capsid protein encoded by L2 were raised in animals. Antigenic determinants on the HPV33 L2 protein were identified by using truncated fusion proteins and were classified as type specific or cross-reactive with respect to HPV1, -8, -11, -16, and -18. Cross-reactive epitopes map to amino acids 98 to 107 or to amino acids 102 to 112 and 107 to 117, respectively, depending on the fusion protein used for immunization. Antibodies directed toward these epitopes detect L2 proteins of HPV11, -16, and -18, but not of HPV1 and -8, in Western immunoblots and enzyme-linked immunosorbent assays. HPV33 L2 amino acids 82 to 94 and 117 to 130 induce type-specific antibodies, with the major response directed to amino acids 117 to 130. By using a synthetic peptide corresponding to L2 amino acids 117 to 130, high-titered, type-specific antisera were obtained. These antisera should be useful as immunological probes for HPV33 infection.

Human papillomavirus type 42: new sequences, conserved genome organization

We report the nucleotide sequence and genome organization of the human papillomavirus type 42. HPV42 DNA was isolated from vulvar papillomas. It has been detected in benign forms of proliferative lesions only. The genome of HPV42 is 7917 bp long and shows the open reading frame pattern conserved in all HPVs sequenced so far. HPV42 has no high degree of sequence homology to any of the known HPVs. It shows characteristics previously found either exclusively in HPVs associated with invasive carcinomas or exclusively in nongenital HPVs. Therefore it cannot be readily ascribed to any of the established subgroups of human papillomaviruses.

Molecular structures of two human DNA topoisomerase I retrosequences

We have isolated recombinant lambda-phage clones that contain sequences complementary to the 3' half of the cDNA encoding human topoisomerase I (hTOP1). These lambda clones belong to three distinct classes: class-I clones contain sequences from the active gene located on human chromosome 20. Class-II and class-III clones contain sequences corresponding to the cDNA encoding hTOP1 from nucleotide (nt) 2208 to 3434 and from nt 1639 to 3434, respectively. These sequences exhibit the characteristic features of retroposons or retrosequences. They are most likely derived from truncated mRNA transcripts of the active gene. We propose to designate the truncated hTOP1 sequence located on chromosome 1 as the pseudogene 1 (psi 1-hTOP1) and the sequence on chromosome 22 as the pseudogene 2 (psi 2-hTOP1). Pseudogene psi 1-hTOP1 has two unique properties: it is flanked by upstream sequences which display promoter activity in transient expression assays, and it contains an open reading frame which could code for the 211 C-terminal amino acids of hTOP1. Pseudogene psi 2-hTOP1 is located within an AluI repetitive element and is flanked on one side by a (CA)21 stretch.