A tetravalent recombinant dengue domain III protein vaccine stimulates neutralizing and enhancing antibodies in mice

Dengue viruses co-circulate as four serologically distinct viruses (DENV1-4) that commonly infect individuals sequentially. Current DENV candidate vaccines incorporate the entire virion envelope E protein (E) ectodomain thereby stimulating both DENV serotype-specific and cross-reactive antibodies. Because the latter may enhance naturally acquired infection, such vaccine formulations must be tetravalent. We evaluated the neutralizing and enhancing antibody response to E domain III (dIII) proteins, in which serotype-specific neutralizing determinants are concentrated. Mice immunized with insect cell-secreted recombinant DENV-dIII proteins individually, and in tetravalent combination, produced serotype-specific IgG1 neutralizing antibodies that nevertheless exhibited measurable DENV enhancing activity in FcγR-bearing cells. Vaccine strategies directed to DENV-dIII-targeted neutralizing antibody production remain attractive but will likely require further modifications to induce safe, protective immunity.

Chronic inhibition of cyclooxygenase-2 attenuates antibody responses against vaccinia infection

Generation of optimal humoral immunity to vaccination is essential to protect against devastating infectious agents such as the variola virus that causes smallpox. Vaccinia virus (VV), employed as a vaccine against smallpox, provides an important model of infection. Herein, we evaluated the importance cyclooxygenase-2 (Cox-2) in immunity to VV using Cox-2 deficient mice and Cox-2 selective inhibitory drugs. The effects of Cox-2 inhibition on antibody responses to live viruses such as vaccinia have not been previously described. Here, we used VV infection in Cox-2 deficient mice and in mice chronically treated with Cox-2 selective inhibitors and show that the frequency of VV-specific B cells was reduced, as well as the production of neutralizing IgG. VV titers were approximately 70 times higher in mice treated with a Cox-2 selective inhibitor. Interestingly, Cox-2 inhibition also reduced the frequency of IFN-gamma producing CD4(+) T helper cells, important for class switching. The significance of these results is that the chronic use of non-steroidal anti-inflammatory drugs (NSAIDs), and other drugs that inhibit Cox-2 activity or expression, blunt the ability of B cells to produce anti-viral antibodies, thereby making vaccines less effective and possibly increasing susceptibility to viral infection. These new findings support an essential role for Cox-2 in regulating humoral immunity.

Dengue virus neutralization is modulated by IgG antibody subclass and Fcgamma receptor subtype

Severe dengue virus (DENV) infection is epidemiologically linked to pre-existing anti-DENV antibodies acquired by maternal transfer or primary infection. A possible explanation is that DENV immune complexes evade neutralization by engaging Fcgamma receptors (FcgammaR) on monocytes, natural targets for DENV in humans. Using epitope-matched humanized monoclonal antibodies (mAbs) and stable FcgammaR-transfected CV-1 cells, we found that DENV neutralization by IgG1, IgG3, and IgG4 mAbs was enhanced in high-affinity FcgammaRIA transfectants and diminished in low-affinity FcgammaRIIA transfectants, whereas neutralization by IgG2 mAbs (low-affinity ligands for both FcgammaRs) was diminished equally. In FcgammaR-negative Vero cells, IgG3 mAbs exhibited the strongest neutralizing activity and IgG2, the weakest. Our results demonstrate that DENV neutralization is modulated by the Fc region in an IgG subclass manner, likely through effects on virion and FcgammaR binding. Thus, the IgG antibody subclass profile generated by DENV infection or vaccination may independently influence the magnitude of the neutralizing response.

Antigenic presentation of heterologous epitopes engineered into the outer surface-exposed helix 4 loop region of human papillomavirus L1 capsomeres

Background

Human papillomavirus (HPV) L1 capsid proteins can self-assemble into pentamers (capsomeres) that are immunogenic and can elicit neutralizing antibodies. Structural modelling of L1 inter-pentameric interactions predicts that helix 4 (h4) of each of the five L1 monomers project laterally and outwards from the pentamer. We sought to utilize HPV L1 capsomeres as a vaccine platform by engineering heterologous epitopes within L1 derivatives deleted for h4 domain.

Results

We used baculovirus – infected Trichoplusia ni cells and ultracentrifugation to synthesize and purify three 16L1 derivatives: one bearing a short deletion (amino acids 404–436) encompassing the h4 domain, and two others, each bearing a conserved neutralizing epitope of the human respiratory syncytial virus (RSV) fusion (F) protein (residues 255–278 and 423–436) that was substituted for the deleted L1 h4 domain residues. Each of the three capsomere derivatives was recognized by anti-L1 antibodies, while two bearing the RSV F-derived moieties were recognized by anti-RSV F antibodies. All three L1 derivatives formed ring-like structures that were similar in morphology and size to those described for native 16L1 capsomeres. When injected into mice, each of the capsomere derivatives was immunogenic with respect to L1 protein, and immunization with chimeric L1-RSV F pentamers resulted in RSV non-neutralizing antisera that recognized purified RSV F protein in immunoblots.

Conclusion

HPV L1 monomers bearing heterologous epitopes within the L1 h4 region can self-assemble into capsomeres that elicit antibody response against such non-HPV encoded epitopes. Thus, the L1 h4 region can function as a novel antigen display site within the L1 pentamer, which in turn may serve as a potential vaccine template.

Difference between the abilities of human Fcgamma receptor-expressing CV-1 cells to neutralize American and Asian genotypes of dengue virus 2

Sera from patients involved in a Peruvian outbreak of dengue virus serotype 1 infection cross-neutralized the American genotype of dengue virus serotype 2 up to 100-fold more efficiently than they did the virulent Asian genotype of dengue virus serotype 2, as determined by a plaque reduction neutralization test (PRNT) with CV-1 fibroblasts modified to express human Fcgamma receptor CD32. The concordant preferential immune enhancement of the Asian genotype of dengue virus serotype 2 in human monocytes suggests that such a modification might strengthen the correlation between the PRNT titer and protection.

An automated Dengue virus microneutralization plaque assay performed in human Fc{gamma} receptor-expressing CV-1 cells

We describe microneutralization assays that used automated 96-well enzyme-linked immunospot (ELI-SPOT) readout instrumentation to measure human anti-dengue virus (DENV) antibodies in CV-1 cells that were stably transfected to express human FcgammaRIIA (CD32) using conventional Vero cells as a comparator. Classic plaque reduction neutralization test (PRNT) end-point titers were determined by probit analysis. Neutralization titers against DENV measured in CV-1 transfectants were expressed in terms of both conventional 50% to 90% PRNT end-point titers and differential infectivity of antibody-treated virus in control and CD32-expressing CV-1 cells. Significantly reduced PRNT titers and strikingly heightened infectivity (up to 100-fold) of antibody-treated DENV was observed in CV-1 CD32 transfectants compared with that observed in control CV-1 or Vero cells. Because DENVs may preferentially replicate in CD32-expressing monocytes/macrophages and dendritic cells, in vivo, it is possible that CD32 introduced into a conventional DENV neutralization assay might provide results that better correlate with protection.

Monocytes, but not T or B cells, are the principal target cells for dengue virus (DV) infection among human peripheral blood mononuclear cells

A better understanding of the pathogenesis of dengue hemorrhagic fever and dengue shock syndrome requires the precise identification of dengue virus (DV) permissive target cells. To examine the relative DV permissiveness among cell subsets, we inoculated unfractionated human peripheral blood mononuclear cells with DV2-16681 in the presence or absence of pooled DV-immune human sera (PHS), and assessed infection with fluorescent dye labeled DV-specific monoclonal antibody and cell surface markers using flow cytometry. We found significantly higher levels of DV antigen staining on DV-infected than mock-infected primary monocytes (3.54 +/- 3.42% vs. 0.50 +/- 0.38%; P = 0.001). The magnitude of infection was markedly enhanced in the presence of highly diluted PHS (10.04 +/- 6.10% vs. 3.54 +/- 3.42%; P = 0.015). Under identical experimental conditions, primary T or B cells were not infected either with or without the addition of PHS (0.06 +/- 0.04% and 0.44 +/- 0.22% for T and B cells, respectively). Furthermore, depletion of CD14+ monocytes prior to DV inoculation abrogated the detection of infected cells, and the addition of monoclonal antibodies to either FcgammaRI (CD64) or FcgammaRII (CD32) led to a 50-70% reduction in antibody-dependent enhancement (ADE) of DV infection. Collectively, these results provide further support to the notion that primary monocytes and FcgammaRs expressed on these cells may be important in the initial steps of immune enhancement observed in some patients with natural DV infection. They also demonstrate that using modern experimental technology, DV infection, and neutralization and enhancement of DV infection can be easily assessed simultaneously in multiple cell types.

Human papillomavirus-like particles mediate functional delivery of plasmid DNA to antigen presenting cells in vivo

Because recombinant empty viral capsids are potentially attractive vectors for gene therapy, here we examined the ability of human papillomavirus (HPV) virus-like particles (VLPs) to mediate delivery and expression of DNA plasmids in vitro and in vivo. VLP-mediated delivery and expression of a GFP reporter construct in vitro was found to be highly dependent upon the presence of full-length L2 protein within the VLPs. Similarly, expression of GFP and luciferase reporter plasmids in vivo was strongly enhanced by co-administration of L1/L2 VLPs. Interestingly, in these experiments we routinely observed GFP expression in migrating antigen presenting cells (APC) recovered from mice inoculated with GFP plasmid in combination with VLPs, but not in APC recovered from mice inoculated with the plasmid alone. Additional evidence to support this concept was generated in experiments in which co-administration of VLPs with a plasmid designed to express HPV16 E6 oncoprotein was associated with significant enhancement of plasmid-encoded E6-specific cellular immune responses. These findings have implications for the design of vaccines for combined prophylaxis and therapy of HPV-associated diseases, and for other vaccines that rely on the administration of DNA-based immunogens, adjuvants, and/or other factors.

Cyclooxygenase-2 Inhibition Attenuates Antibody Responses against Human Papillomavirus-Like Particles

Vaccination to generate protective humoral immunity against infectious disease is becoming increasingly important due to emerging strains of virus, poorly immunogenic vaccines, and the threat of bioterrorism. We demonstrate that cyclooxygenase-2 (Cox-2) is crucial for optimal Ab responses to a model vaccine, human papillomavirus type 16 virus-like particles (HPV 16 VLPs). Cox-2-deficient mice produce 70% less IgG, 50% fewer Ab-secreting cells, and 10-fold less neutralizing Ab to HPV 16 VLP vaccination compared with wild-type mice. The reduction in Ab production by Cox-2(-/-) mice was partially due to a decrease in class switching. SC-58125, a structural analog of the Cox-2-selective inhibitor Celebrex reduced by approximately 70% human memory B cell differentiation to HPV 16 VLP IgG-secreting cells. The widespread use of nonsteroidal anti-inflammatory drugs and Cox-2-selective inhibitory drugs may therefore reduce vaccine efficacy, especially when vaccines are poorly immunogenic or the target population is poorly responsive to immunization.

Differential enhancement of dengue virus immune complex infectivity mediated by signaling-competent and signaling-incompetent human Fcgamma RIA (CD64) or FcgammaRIIA (CD32)

Fcgamma receptor (FcgammaR)-mediated entry of infectious dengue virus immune complexes into monocytes/macrophages is hypothesized to be a key event in the pathogenesis of complicated dengue fever. FcgammaRIA (CD64) and FcgammaRIIA (CD32), which predominate on the surface of such dengue virus-permissive cells, were compared for their influence on the infectivity of dengue 2 virus immune complexes formed with human dengue virus antibodies. A signaling immunoreceptor tyrosine-based activation motif (ITAM) incorporated into the accessory gamma-chain subunit that associates with FcgammaRIA and constitutively in FcgammaRIIA is required for phagocytosis mediated by these receptors. To determine whether FcgammaRIA and FcgammaRIIA activation functions are also required for internalization of infectious dengue virus immune complexes, we generated native and signaling-incompetent versions of each receptor by site-directed mutagenesis of ITAM tyrosine residues. Plasmids designed to express these receptors were transfected into COS-7 cells, and dengue virus replication was measured by plaque assay and flow cytometry. We found that both receptors mediated enhanced dengue virus immune complex infectivity but that FcgammaRIIA appeared to do so far more effectively. Abrogation of FcgammaRIA signaling competency, either by expression without gamma-chain or by coexpression with gamma-chain mutants, was associated with significant impairment of phagocytosis and of dengue virus immune complex infectivity. Abrogation of FcgammaRIIA signaling competency was also associated with equally impaired phagocytosis but had no discernible effect on dengue virus immune complex infectivity. These findings point to fundamental differences between FcgammaRIA and FcgammaRIIA with respect to their immune-enhancing capabilities and suggest that different mechanisms of dengue virus immune complex internalization may operate between these FcgammaRs.

Prevalence of human papillomavirus genotypes and related abnormalities of cervical cytological results among HIV-1-infected women in Rochester, New York

Women with human immunodeficiency virus (HIV) infection have higher rates of concurrent human papillomavirus (HPV) infection and cervical dysplasia than do HIV-uninfected women. They are also more commonly infected with multiple HPV types simultaneously. To determine the prevalence of different HPV genotypes in a group of HIV-infected women and to correlate these findings with cervical cytological results, we studied a group of 229 women attending a university-based HIV clinic during a 7-year period. When cervicovaginal lavage specimens, the reverse line-blot assay, and DNA sequencing were used, the most commonly detected HPV types (in decreasing order of frequency) were 56, 53, 16, 58, 52, MM7, MM8, and 33. These results contrast sharply with similar studies of HIV-uninfected women, in whom HPV-16 and -18 generally predominate. In our study, the HPV types most commonly associated with low-grade squamous intraepithelial lesions (SILs) were 56 and 53. Types most commonly associated with high-grade SILs were 52 and 58. High-risk HPV types other than 16 and 18 are often found in HIV-infected women and are frequently associated with abnormal cervical cytological results in this setting. These observations have implications for the design of future HPV vaccines.

Local radiation therapy of B16 melanoma tumors increases the generation of tumor antigen-specific effector cells that traffic to the tumor

Immunotherapy of cancer is attractive because of its potential for specificity and limited side effects. The efficacy of this approach may be improved by providing adjuvant signals and an inflammatory environment for immune cell activation. We evaluated antitumor immune responses in mice after treatment of OVA-expressing B16-F0 tumors with single (15 Gy) or fractionated (5 x 3 Gy) doses of localized ionizing radiation. Irradiated mice had cells with greater capability to present tumor Ags and specific T cells that secreted IFN-gamma upon peptide stimulation within tumor-draining lymph nodes than nonirradiated mice. Immune activation in tumor-draining lymph nodes correlated with an increase in the number of CD45(+) cells infiltrating single dose irradiated tumors compared with nonirradiated mice. Similarly, irradiated mice had increased numbers of tumor-infiltrating lymphocytes that secreted IFN-gamma and lysed tumor cell targets. Peptide-specific IFN-gamma responses were directed against both the class I and class II MHC-restricted OVA peptides OVA(257-264) and OVA(323-339), respectively, as well as the endogenous class I MHC-restricted B16 tumor peptide tyrosinase-related protein 2(180-188). Adoptive transfer studies indicated that the increased numbers of tumor Ag-specific immune cells within irradiated tumors were most likely due to enhanced trafficking of these cells to the tumor site. Together these results suggest that localized radiation can increase both the generation of antitumor immune effector cells and their trafficking to the tumor site.

A human papillomavirus type 16 vaccine by oral delivery of L1 protein

To establish an edible HPV16 vaccine, we constructed a recombinant HPV16 L1-expressing Schizosaccharomyces pombe yeast strain (HPV16L1 yeast). A preliminary study revealed that freeze-dried yeast cells could be delivered safely, and were digested in the mouse intestine. The freeze-dried HPV16 L1 yeast was administered orally as an edible vaccine, with or without the mucosal adjuvant heat-labile toxin LT (R192G), to 18 female BALB/c mice. After the third immunization, none of the mice that received the edible HPV16 vaccine showed specific antibody responses, whereas all of the positive controls that were administered intranasally with 5 microg of HPV16-virus-like particles (VLP) had serum IgG, and genital IgA and IgG that reacted with HPV16-VLP in enzyme-linked immunosorbent assays (ELISAs). When a suboptimal dose (1 microg) of HPV16-VLP was administered to all the mice, including the negative control mice, 50% of the mice that were pre-immunized with the edible HPV16 vaccine showed positive serum IgG responses, while none of the negative controls showed any response. Vaginal IgG and IgA antibodies were also elicited in 33 and 39%, respectively, of the mice that were given with the edible HPV16 vaccine and the intranasal boost. All of the antibodies reacted more strongly to intact HPV16-VLP than to denatured HPV16-L1 protein suggesting that the edible vaccine primes for antibody responses against conformation-dependent epitopes. The inclusion of adjuvant in the vaccine formulation marginally increased the genital IgA response (P=0.06). HPV16-L1 protein in the yeast might induce tolerance in the vaccinated animals that could be recovered by intranasal boosting with a suboptimal dose of HPV-VLP. This freeze-dried yeast system may be useful as an oral delivery of HPV 16 L1 protein.

Expression of Human papillomavirus type 16 major capsid protein in transgenic Nicotiana tabacum cv. Xanthi

The production of vaccine antigens in plants is a safe and potentially very cost-effective alternative to traditional expression systems. We investigated the possibility of transgenic plant expression of the Human papillomavirus (HPV) type 16 L1 major capsid protein, with and without nuclear localisation signals, in Nicotiana tabacum cv. Xanthi plants. The genes were stably integrated into the N. tabacum genome, and both the expressed proteins were capable of assembling into capsomers and virus-like particles. The proteins in concentrated leaf extracts (L1(Tr)) were tested for antigenicity using a panel of characterised monoclonal antibodies (Mabs). Neutralising and conformation-specific Mabs (H16:V5 and H16:E70) were shown to bind to both types of the plant-produced particles. We estimated the L1(Tr) product yield to be 2-4 microg per kg of fresh leaf material. Rabbits immunised with small doses of plant-produced particles elicited a weak anti-HPV-16 L1 immune response. Our results support the feasibility of using transgenic plants for the production of HPV vaccines.

Oral immunogenicity of human papillomavirus-like particles expressed in potato

Human papillomavirus-like particles (HPV VLPs) have shown considerable promise as a parenteral vaccine for the prevention of cervical cancer and its precursor lesions. Parenteral vaccines are expensive to produce and deliver, however, and therefore are not optimal for use in resource-poor settings, where most cervical HPV disease occurs. Transgenic plants expressing recombinant vaccine immunogens offer an attractive and potentially inexpensive alternative to vaccination by injection. For example, edible plants can be grown locally and can be distributed easily without special training or equipment. To assess the feasibility of an HPV VLP-based edible vaccine, in this study we synthesized a plant codon-optimized version of the HPV type 11 (HPV11) L1 major capsid protein coding sequence and introduced it into tobacco and potato. We show that full-length L1 protein is expressed and localized in plant cell nuclei and that expression of L1 in plants is enhanced by removal of the carboxy-terminal nuclear localization signal sequence. We also show that plant-expressed L1 self-assembles into VLPs with immunological properties comparable to those of native HPV virions. Importantly, ingestion of transgenic L1 potato was associated with activation of an anti-VLP immune response in mice that was qualitatively similar to that induced by VLP parenteral administration, and this response was enhanced significantly by subsequent oral boosting with purified insect cell-derived VLPs. Thus, papillomavirus L1 protein can be expressed in transgenic plants to form immunologically functional VLPs, and ingestion of such material can activate potentially protective humoral immune responses.

Mucosal immunoglobulin-A and -G responses to oncogenic human papilloma virus capsids

Oncogenic human papilloma virus (HPV) infection is the most important risk factor for developing cervical cancer. It is known that serum antibody responses against these viruses are associated with persistent infection. We conducted an epidemiological study of 627 women to detect cervical mucosal immunoglobulin (Ig)A and IgG responses to oncogenic HPV capsids. Antibody reactivity and cervical HPV infection genotypes were examined by enzyme-linked immunosorbent assay (ELISA) using HPV types 16, 18, 31, and 45 virus-like particles, and a polymerase chain reaction-based method, respectively. HPV infection was defined as being positive for HPV DNA. Multivariate analysis revealed that a mucosal IgA response was associated with the HPV infection, whereas the IgG response was associated with high-grade cervical squamous intraepithelial lesions (SIL)/squamous cell cancer (SCC) and subject age (40-49 years). IgA was positive in 72% of women with oncogenic HPV infections, whereas IgG was positive in 64% of women with high-grade SIL/SCC. The longitudinal study demonstrated that the IgA response was elicited earlier than the IgG response, and the IgG response was barely induced in the preclinical HPV infection. However, once an IgG response was induced, it persisted longer after HPV clearance. The mucosal IgA response reflects current HPV infection, whereas an IgG response may be induced with the development of cervical lesions.

The L1 major capsid protein of human papillomavirus type 11 interacts with Kap beta2 and Kap beta3 nuclear import receptors

We have previously shown that the L1 major capsid protein of low-risk HPV11 binds to the Kap alpha2 adapter and enters the nucleus via a Kap alpha2beta1-mediated pathway. In this study, we discovered that HPV11 L1 capsomeres bind to Kap beta2 import receptor, known to mediate nuclear import of hnRNP A1 via interaction with its nuclear localization signal termed M9. Significantly, binding of HPV11 L1 capsomeres to Kap beta2 inhibited the nuclear import of Kap beta2, and its specific M9-containing cargo. Interestingly, HPV11 L1 capsomeres also interacted with Kap beta3 import receptor and inhibited Kap beta3 nuclear import. Moreover, the L1 capsomeres of high-risk HPV-16 shared these activities. These data suggest that HPV L1 major capsid proteins interact with Kap beta2 and Kap beta3, and they may inhibit the Kap beta2- and Kap beta3-mediated nuclear import pathways during the productive phase of the viral life cycle when the virions are assembled and released.

Nuclear import strategies of high risk HPV16 L1 major capsid protein

During the late phase of human papillomavirus (HPV) infection, the L1 major capsid proteins enter the nuclei of host epithelial cells and, together with the L2 minor capsid proteins, assemble the replicated viral DNA into virions. We investigated the nuclear import of the L1 major capsid protein of high risk HPV16. When digitonin-permeabilized HeLa cells were incubated with HPV16 L1 capsomeres, the L1 protein was imported into the nucleus in a receptor-mediated manner. HPV16 L1 capsomeres formed complexes with Kap alpha2beta1 heterodimers via interaction with Kap alpha2. Accordingly, nuclear import of HPV16 L1 capsomeres was mediated by Kap alpha2beta1 heterodimers, required RanGDP and free GTP, and was independent of GTP hydrolysis. Remarkably, HPV16 L1 capsomeres also interacted with Kap beta2 and binding of RanGTP to Kap beta2 did not dissociate the HPV16 L1.Kap beta2 complex. Significantly, HPV16 L1 capsomeres inhibited the nuclear import of Kap beta2 and of a Kap beta2-specific M9-containing cargo. These data suggest that, during the productive stage of infection, while the HPV16 L1 major capsid protein enters the nucleus via the Kap alpha2beta1-mediated pathway to assemble the virions, it also inhibits the Kap beta2-mediated nuclear import of host hnRNP A1 protein and, in this way, favors virion formation.

Single-cell cytokine analysis allows detection of cervical T-cell responses against human papillomavirus type 16 L1 in women infected with genital HPV

Specific types of human papillomavirus (HPV) are known to play a causal role in the development of cervical cancer, with human papillomavirus type 16 (HPV-16) identified as the predominant type. Despite this, little is known about cervical immune responses to this pathogen. The aim of this study was to assess the feasibility of cervical cytobrush sampling and single-cell cytokine staining to investigate cervical lymphocyte-specific cytokine responses to HPV-16 antigens. Of eighteen women recruited into the study, five were HPV DNA positive at the cervix (current exposure) and a further five had circulating antibodies to HPV-16 (previous exposure). Cervical lymphocytes, isolated from the five HPV DNA-positive women, two HPV DNA-negative controls, and one woman with circulating HPV-16 antibodies were assessed for HPV-specific responses using intracellular staining for interferon-gamma (IFN-gamma) and interleukin-4 (IL-4). We demonstrate that both CD4(+) and CD8(+) cervical T lymphocytes, harvested from noninfected and infected subjects, produce these cytokines in response to nonspecific stimulation. However, antigen-specific (HPV-16 L1) IFN-gamma production by CD4(+) and CD8(+) cervical T lymphocytes is only detectable in women exposed currently or previously to HPV-16. This is the first time that antigen-specific cytokine responses of mucosal lymphocytes, obtained from a site of HPV infection, have been demonstrated. This finding clearly illustrates the use of intracellular cytokine staining for investigation of low precursor frequency single-cell antigen-specific responses in lymphocytes harvested from mucosal sites with HPV infection.

Oral antibodies to human papillomavirus type 16 in women with cervical neoplasia

This study investigated the relationship between human papillomavirus type 16 (HPV-16) antibodies detected in oral fluid from women with cervical neoplasia, their HPV-16 antibody seroprevalence, and their cervical HPV-16 DNA presence. Cervical HPV-16 DNA was detected by polymerase chain reaction in 43.2% (35/81) of these women. The prevalence of IgG and IgA antibodies to HPV-16 virus-like particles (VLP-16) in oral fluid and was investigated by enzyme-linked immunosorbent assay. Anti-VLP-16 IgA antibodies were detected in oral fluid from 54.3% (44/81) of women with cervical neoplasia, compared with 8% (3/36) in controls (P = 0.000002). Anti-VLP-16 IgG was detected in oral fluid from 43.2.9% (25/72) and 13.3% (4/30; P = 0.029), respectively. Women who were HPV-16 DNA positive at their cervical lesion, displayed an oral fluid anti-VLP-16 IgA prevalence of 60.7% (17/28) and HPV-16 DNA negative women an oral fluid anti-VLP-16 IgA prevalence of 50% (20/40; P = 0.38). Oral fluid anti-VLP-16 IgG prevalence in HPV-16 DNA positive women was 28.6% (8/28) compared with 40% (16/40) in oral fluid from HPV-16 DNA negative women (P = 0.3). Amongst HPV-16 DNA positive women, the anti-VLP-16 IgG seroprevalence was 75% (21/28) and IgA seroprevalence 35.7% (10/28) and for the HPV-16 DNA negative women these values were 60% (24/40) and 32.5% (13/40), respectively. Oral IgA antibody testing proved no more sensitive than serum antibody detection for the determination of HPV infection but could be useful as a non-invasive screening method for women with cervical neoplasia and for estimating the mucosal antibody response to HPV vaccines.

A Phase 1 study of a recombinant viruslike particle vaccine against human papillomavirus type 11 in healthy adult volunteers

Viruslike particles (VLPs) produced from the L1 protein of several papillomaviruses have induced protection from infection after live challenge in animal models. In the present study, the safety and immunogenicity of a human papillomavirus (HPV)--11 L1 VLP candidate vaccine were measured in a phase 1, dose-finding trial in humans. The vaccine was well tolerated and induced high levels of both binding and neutralizing antibodies. Marked increases in lymphoproliferation to HPV--11 L1 antigens were noted after the second vaccination. In addition, lymphoproliferation was induced after vaccination in peripheral blood mononuclear cells (PBMC) stimulated with heterologous L1 VLP antigens of HPV types 6 and 16. Statistically significant increases in HPV antigen--specific interferon--gamma and interleukin-5 production were measured from PBMC culture supernatants. This candidate HPV VLP vaccine induced robust B and T cell responses, and T cell helper epitopes appear to be conserved across HPV types.

Human papillomavirus virus-like particles are efficient oral immunogens when coadministered with Escherichia coli heat-labile enterotoxin mutant R192G or CpG DNA

Certain human papillomaviruses (HPVs) cause most cervical cancer, which remains a significant source of morbidity and mortality among women worldwide. HPV recombinant virus-like particles (VLPs) are promising vaccine candidates for controlling anogenital HPV disease and are now being evaluated as a parenteral vaccine modality in human subjects. Vaccines formulated for injection generally are more costly, more difficult to administer, and less acceptable to recipients than are mucosally administered vaccines. Since oral delivery represents an attractive alternative to parenteral injection for large-scale human vaccination, the oral immunogenicity of HPV type 11 (HPV-11) VLPs in mice was previously investigated; it was found that a modest systemic neutralizing antibody response was induced (R. C. Rose, C. Lane, S. Wilson, J. A. Suzich, E. Rybicki, and A. L. Williamson, Vaccine 17:2129-2135, 1999). Here we examine whether VLPs of other genotypes may also be immunogenic when administered orally and whether mucosal adjuvants can be used to enhance VLP oral immunogenicity. We show that HPV-16 and HPV-18 VLPs are immunogenic when administered orally and that oral coadministration of these antigens with Escherichia coli heat-labile enterotoxin (LT) mutant R192G (LT R192G) or CpG DNA can significantly improve anti-VLP humoral responses in peripheral blood and in genital mucosal secretions. Our results also suggest that LT R192G may be superior to CpG DNA in this ability. These findings support the concept of oral immunization against anogenital HPV disease and suggest that clinical studies involving this approach may be warranted.

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.

The impact of human immunodeficiency virus type 1 status on human papillomavirus (HPV) prevalence and HPV antibodies in serum and cervical secretions

Human immunodeficiency virus (HIV) type 1-infected (HIV-positive) and -uninfected (HIV-negative) sex workers were examined for the presence of cervical human papillomavirus (HPV) DNA. Cervicovaginal rinse and serum samples from these women were examined for IgG and IgA antibodies to HPV-16 virus-like particles (VLP-16) by ELISA. The HIV-positive women displayed a significantly higher prevalence of HPV DNA (40/47 [85%]) than did the HIV-negative women (22/52 [42%]; P=.00001). Both HIV-positive and HIV-negative sex workers displayed a high seroprevalence rate for anti-VLP-16 IgG antibodies (27/40 [68%] and 30/43 [70%], respectively), but significantly fewer HIV-positive women than HIV-negative women had anti-VLP-16 serum IgA (6/40 [15%] vs. 17/43 [40%], respectively; P=.012). Significantly more HIV-positive women than HIV-negative women had cervical anti-VLP-16 IgG antibodies (16/49 [33%] vs. 6/63 [10%], respectively; P=.002) but not IgA antibodies (P=.3).

Nuclear import and DNA binding of human papillomavirus type 45 L1 capsid protein

During the life cycle of human papillomaviruses (HPVs), the L1 capsid proteins seem to enter the nucleus twice: once after the virions infect the cells, and later during the productive phase when they assemble the replicated HPV genomic DNA into infectious virions. We established for the high-risk HPV45 that when digitonin-permeabilized HeLa cells were incubated with L1 homopentameric capsomers, the HPV45 L1 protein was imported into the nucleus in a receptor-mediated manner. In contrast, intact capsids were not able to enter the nucleus. Immunoisolation assays showed that HPV45 L1 capsomers interact with cytosolic karyopherin alpha 2 beta 1 heterodimers. HPV45 L1 bound strongly to karyopherin alpha 2, and weakly to karyopherin beta 1, as did its nuclear localization signal (NLS). Nuclear import of HPV45 L1, or of a GST-NLS(HPV45L1) fusion protein was efficiently mediated by karyopherin alpha 2 beta 1 heterodimers, and only weakly by karyopherin beta 1. Nuclear import required RanGDP, but was independent of GTP hydrolysis by Ran. Together, these data suggest that the major nuclear import pathway for HPV45 L1 major capsid protein in infected host cells is mediated by karyopherin alpha 2 beta 1 heterodimers and that GTP hydrolysis by Ran is not required for import. Remarkably, HPV45 L1 capsomers can interact nonspecifically with different types of HPV-DNA, and the DNA binding region of HPV45 L1 overlaps with its NLS sequence.

Seroresponses to human papillomavirus types 16, 18, 31, 33, and 45 virus-like particles in South African women with cervical cancer and cervical intraepithelial neoplasia

The aim of the study was to determine the prevalence of antibodies to human papillomavirus (HPV) types 16, 18, 31, 33, and 45 in woman in Cape Town with cervical intraepithelial neoplasia (CIN) (n = 95), cervical cancer (n = 40), female blood donors (n = 95) and children (n = 110). The enzyme-linked immunosorbent assay (ELISA) made use of baculovirus synthesised HPV virus like particles (VLPs) as antigen. Antibodies to at least one HPV type were detected in sera from 75% of cancer patients, 71.6% of CIN patients, 44.2% of blood donors and 27.3% of children. Sera from 95 women with CIN were compared with age-matched female blood donors. There was a significant association of seropositivity to VLP-16 (P = 0.006) and VLP-45 (P = 0.008) with CIN compared with the blood donors. There was also a significant difference in the seropositivity of women with CIN to any of the five virus-like particle (VLP) types compared to the blood donors (P = 0.0002: OR = 3.2). Thirty-nine of sixty-nine (56.5%) women with CIN were found to be HPV-16 DNA positive. The average age of women in this group that were VLP-16 seropositive was 34 years and those found to be VLP-16 seronegative was 52 years of age. Antibodies to all five VLP types were detected in these populations, thus an ideal vaccine should induce protection from infection by a wide range of HPV types.

Seroresponses to virus-like particles of human papillomavirus types 16, 18, 31, 33, and 45 in San people of Southern Africa

Virus-like particles (VLPs) of the high-risk human papillomavirus (HPV) types 16, 18, 31, 33, and 45 were used as antigen in enzyme-linked immunosorbent assay (ELISA) to determine the prevalence of serum IgG in a group of San people originally from Namibia, now residing in South Africa. The San children had low seroprevalence to all VLP types, but 26/115 (22.6%) of the children were seropositive to at least 1 VLP type. Among the adults, seroprevalence was significantly higher. The seroprevalence of antibodies in 101 San women to VLP-16 was 16.8%, VLP-18 18.8%, VLP-31 12.9%, VLP-33 17.8%, and VLP-45 22.8%. Five of the 11 men were seropositive: 2 for VLP-31, 1 for VLP-18, 1 for VLP-33, and 1 for VLP-45. Seroreactivity appeared to be type specific, except possibly to VLP-18 and -45. Of the adults, 50.5% were seropositive to at least 1 VLP type and 24.8% were seropositive to >1 VLP type. From this study, it is concluded that the San people are exposed to HPV-16, -18, -31, -33, and -45, with antibodies to VLP-45 being the most prevalent.

Nuclear import of HPV11 L1 capsid protein is mediated by karyopherin alpha2beta1 heterodimers

L1 major capsid proteins of human papillomaviruses (HPVs) enter the nuclei of host cells at two times during the viral life cycle: 1) after infection and 2) later during the productive phase, when they assemble the replicated HPV genomic DNA into infectious virions. L1 proteins are stable in two oligomeric configurations: as homopentameric capsomers, and as capsids composed of 72 capsomers. We found that intact L1 capsids of HPV type 11 cannot enter the nucleus, suggesting that capsid disassembly may be required for HPV11 L1 nuclear import. We established that HPV11 L1 is imported in a receptor-mediated manner into the nuclei of digitonin-permeabilized HeLa cells. HPV11 L1 docked at the nuclear pore complexes via karyopherin alpha2beta1 heterodimers. Anti-karyopherin-beta1 and anti-karyopherin alpha2 antibodies specifically inhibited nuclear import of HPV11 L1. Moreover, nuclear import of HPV11 L1 could be reconstituted using karyopherin alpha2, beta1, RanGDP and p10. In agreement with the docking and import data, we found that HPV11 L1 binds to karyopherin alpha2 and that this interaction is inhibited by a peptide representing the classical nuclear localization signal of SV40 T antigen. These results strongly suggest that HPV11 L1 enters the nucleus of the infected host cell via the karyopherin alpha2beta1 pathway.

Glutathione-dependent ascorbate recycling activity of rat serum albumin

An efficient regeneration of vitamin C (ascorbate) from its oxidized byproduct, dehydroascorbate (DHAA), is necessary to maintain sufficient tissue levels of the reduced form of the vitamin. Additionally, the recycling may be more significant in mammals, such as guinea pigs and humans, who have lost the ability to synthesize ascorbate de novo, than it is in most other mammals who have retained the ability to synthesize the vitamin from glucose. Both a chemical and an enzymatic reduction of DHAA to ascorbate have been proposed. Several reports have appeared in which proteins, including thioltransferase, protein disulfide isomerase, and 3-alpha-hydroxysteroid dehydrogenase, characterized for other activities have been identified as having DHAA reductase activity in vitro. Whether these previously characterized proteins catalyze the reduction of DHAA in vivo is unclear. In the present study, a 66 kD protein was purified strictly on the basis of its DHAA-reductase activity and was identified as rat serum albumin. The protein was further characterized and results support the suggestion that serum albumin acts as an antioxidant and exerts a significant glutathione-dependent DHAA-reductase activity that may be important in the physiologic recycling of ascorbic acid.

Oral vaccination of mice with human papillomavirus virus-like particles induces systemic virus-neutralizing antibodies

To assess whether oral vaccination against human papillomavirus (HPV) may be feasible, we administered HPV virus-like particles (VLPs) to mice by gavage. Enzyme-linked immunosorbent assay (ELISA) results indicated that serum anti-VLP immunoglobulin G (IgG) and IgA antibodies were induced after oral vaccination, and these responses demonstrated antigenic specificities that were conformationally dependent and restricted according to HPV genotype. Importantly, orally induced postimmune sera were found to neutralize HPV-11 virions in vitro. These results indicated that the VLPs were antigenically stable in the environment of the gastrointestinal tract and were able to engage in potentially useful immune system interactions. These findings support the concept of oral vaccination against anogenital HPV disease, and suggest the possibility that this may be a useful approach to the immunization of large populations against cervical cancer and other HPV associated diseases.

Water soluble antioxidants in mammalian aqueous humor: interaction with UV B and hydrogen peroxide

HPLC/electrochemical detection was used to identify five major low MW water soluble electrochemically active molecules from the aqueous humor of three species of mammals: New Zealand White rabbits and humans (diurnal) and Sprague-Dawley rats (nocturnal). These molecules are L-cysteine (CYS), L-ascorbic acid (AA), glutathione (GSH), uric acid (UA) and L-tyrosine (TYR); all of these molecules have known antioxidant properties. Nocturnal rat aqueous humor is concentrated in two thiols: GSH (125 microM; n = 24 pooled eyes) and CYS (63 microM), in contradistinction to diurnal species which have high concentrations of AA. No deterioration of any of these antioxidants occurs in a synthetic aqueous humor mixture irradiated with a physiologically relevant spectral UV B dose of 30 mJ/cm2/h (5.5 UV equivalent sunlight hours). The same result occurred with addition of the endogenous aqueous humor UV B photosensitizer L-tryptophan. In a second set of experiments, human synthetic aqueous humor was subjected to hydrogen peroxide induced oxidant stress. The decay of antioxidants was CYS > GSH > AA > UA > TYR. The second highest concentrated antioxidant in human aqueous humor is TYR. Yet TYR failed to protect AA against H2O2-induced free radical damage in a synthetic aqueous humor model system (P = 0.10; ANOVA). The existence of multiple electrochemically active constituents and their thermodynamic interactions must be recognized when choosing animal models to evaluate human aqueous humor antioxidant defense.

Vitamin supplementation and breast cancer: is homeostasis a factor?

Recent observations by several research groups on many thousands of women have yielded the disappointing view that mega-dose vitamin supplementation does not provide significant protection against breast cancer. This is a review of the pertinent literature with a goal of identifying testable hypotheses that might explain the epidemiology and be helpful in designing subsequent evaluations. In one hypothesis presented, the vitamin content of peripheral cells that protect breast epithelium is not markedly affected by supplementation. In the second hypothesis the metabolic status (redox state) of epithelial cells is more important than the absolute level (reduced plus oxidized) of each antioxidant. In either case, extremes in diet fail to alter inherent homeostatic mechanisms.

Human papillomavirus type 11 recombinant L1 capsomeres induce virus-neutralizing antibodies

The human papillomavirus type 11 (HPV-11) L1 major capsid protein can be trypsinized to generate recombinant capsomeres that retain HPV genotype-restricted capsid antigenicity (M. Li, T. P. Cripe, P. A. Estes, M. K. Lyon, R. C. Rose, and R. L. Garcea, J. Virol. 71:2988-2995, 1997). In the present study, HPV-11 virion-neutralizing monoclonal antibodies H11.F1 and H11.H3, previously characterized as recognizing two distinct HPV-11 capsid-neutralizing antigenic domains (S. W. Ludmerer, D. Benincasa, and G. E. Mark III, J. Virol. 70:4791-4794, 1996), were each found to be highly immunoreactive with trypsin-generated capsomeres in an enzyme-linked immunosorbent assay (ELISA). Capsomeres were used to generate high-titer polyclonal immune sera that demonstrated HPV genotype-restricted reactivity by ELISA. The capsomere antisera were then tested in an in vitro infectivity assay and found to neutralize HPV-11 virions. In this assay, HPV-11 capsomere polyclonal antisera exhibited neutralization titers (10(-5) to 10(-6)) comparable to those obtained with a virion-neutralizing antiserum raised previously against intact HPV-11 VLPs (R. C. Rose, R. C. Reichman, and W. Bonnez, J. Gen. Virol. 75:2075-2079, 1994). These results indicate that highly immunogenic, genotype-restricted HPV capsid-neutralizing antigenic domains are contained entirely within capsomeres. Thus, capsomeres may be viable vaccine candidates for the prevention of HPV disease.

Isolation and propagation of human papillomavirus type 16 in human xenografts implanted in the severe combined immunodeficiency mouse

We report the isolation and propagation of human papillomavirus type 16, the main agent of cervical cancer, using human foreskin fragments implanted in severe combined immunodeficiency mice. The infection produced viral particles, and with each passage of the virus it caused lesions identical to intraepithelial neoplasia, the precursor to carcinoma.

Ocular oxidants and antioxidant protection

Oxidative damage and antioxidant protection in ocular tissues has not been reviewed recently. Metabolism in the eye is of increasing interest because the organ is highly susceptible to damage by sunlight, oxygen, various chemicals, and pollutants. Interest is expected to increase because of an aging Western world population and a continued depletion of stratospheric ozone. Hydrogen peroxide is discussed because it is both a byproduct and a source of free radical reactions and is normally present in the aqueous humor. The metabolism of reactive oxygen species by enzymes, nutrients, pigments, and low molecular weight scavengers is evaluated. Ascorbic acid, because of its high concentration in the eye, is thought to be a primary substrate in ocular protection; progress in determining the mechanisms by which it is recycled and maintained in the useful, reduced state is discussed. Recent information is included about antioxidants not previously known to be present in the eye, and some importance is placed on the properties of the vitreous humor and tear fluid because of the previous lack of emphasis on these.

Tear fluid content of electrochemically active components including water soluble antioxidants

PURPOSE

To describe the content of water-soluble antioxidants in tear fluid.

METHODS

We collected tear fluid from healthy subjects, either into borosilicate glass tubing or by absorption onto Schirmer strips. High pressure liquid chromatography with electrochemical detection provided data on several components in a single assay. The system was sufficiently sensitive to provide reliable values for components present in tear fluid collected at normal (basal) or stimulated rates of secretion.

RESULTS

Tear fluid at basal secretion was found to contain four compounds often considered to function in biology as antioxidants. Ascorbic acid (AA) is found at 665 microM, tyrosine at 45 microM and glutathione (GSH) at 107 microM. Cysteine (48 microM) and uric acid (328 microM) are reported for the first time; the latter is somewhat controversial as a physiologically active antioxidant. One peak on the chromatogram was consistently present but has not been identified. During stimulation of flow by brief inhalation of ammonium hydroxide fumes, the concentration of each compound was lower.

CONCLUSION

This work demonstrates the presence of electro-chemically active components that might function as antioxidants at the anterior surface of the cornea against potential damage from radiation, oxygen toxicity, abrasion and environmental chemicals.

In vitro infection and type-restricted antibody-mediated neutralization of authentic human papillomavirus type 16

Human papillomavirus type 16 (HPV-16) is strongly associated with the development of cervical cancer. Studies of model systems with animal papillomaviruses have demonstrated the importance of neutralizing antibodies in preventing papillomavirus-associated disease. The assessment of neutralizing antibody responses against HPV-16, previously hampered by the lack of a viral source, was enabled by the recent propagation of an HPV-16 stock in xenografted severe combined immunodeficiency (SCID) mice. HPV-16 infection of an immortalized human keratinocyte cell line was demonstrated by detection of an HPV-16-specific spliced mRNA amplified by reverse transcriptase PCR. Infection was blocked by preincubation of the virus with antiserum generated against HPV-16 virus-like particles (VLPs) composed of the major capsid protein, L1. To examine potential cross-neutralizing activity among the different genital HPV types, rabbit antisera to L1 VLPs corresponding to HPV-6, -11, -18, -31, -33, -35, -39, and -45 were assayed for the ability to block the HPV-16 infection of cultured cells. Antiserum raised against HPV-33 L1 VLPs was the only heterologous antiserum which inhibited HPV-16 infection. Thus, a neutralization assay for HPV-16 may help to characterize the components required to compose a broadly efficacious genital HPV vaccine.

Properties of electrochemically active components in mammalian vitreous humor

Antioxidants are considered to have important roles in protecting the eye against radiation, oxygen toxicity and other threats. Several water-soluble electrochemically-active compounds that might function as antioxidants in vitreous humor of rabbit, rat and bovine eyes were identified and quantitated. In that the rat is a nocturnal animal species and the other two are diurnal, the results allow a tentative evaluation on the comparative physiology of light-dark behavior patterns that influence this ocular fluid. All analyses were performed by HPLC with electrochemical detection. The utility of this approach is that components of vitreous humor can be identified by their retention time and by their characteristic response when the voltages of the two sensing electrodes are progressively brought together. Four compounds regarded as functional antioxidants in the animal kingdom were identified and quantitated. Other antioxidants known to be present in several biological fluids are not present at detectable or significant levels in vitreous humor; metabolites or precursors of these might be present in trace quantities.

Serological and T-helper cell responses to human papillomavirus type 16 L1 in women with cervical dysplasia or cervical carcinoma and in healthy controls

In a cross-sectional study we have investigated serological and T-helper (Th) cell responses to human papillomavirus type 16 (HPV-16) L1 in women with HPV-16 related diseases and related them to cervical histology and HPV DNA status. Using a virus-like particle (VLP) based ELISA to detect antibodies to the HPV-16 L1 capsid protein, 45% (33/73) of women with cervical dysplasia, 40% (2/5) of women with cervical cancer, 36% (4/11) of healthy adult female controls and 6% (2/35) of healthy children were found to be seropositive. Amongst women with cervical dysplasia, the highest levels of seropositivity were found in those who were HPV-16 DNA positive (60%, 15/25) or positive for any of the "high-risk' HPV types, 16/18/33 (58%, 18/31), when compared with those with HPV type "X' (25%, 5/20) or with healthy children (6%, 2/35; P < 0.05 for all comparisons). There was a trend for women with cervical dysplasia to show an increased level of seropositivity with increasing grade of lesion. There was no direct correlation found between seropositivity and Th cell responses in all groups studied. However, a combined analysis of each individual's Th and B cell responses suggests that a Th1 pattern of response is predominant amongst healthy adult controls (80% of responders) but reduced in women with cervical dysplasia (55% of responders). A trend towards a decrease in Th1 type responses was also noted with increasing grade of dysplastic lesion. These findings provide further evidence for the importance of the Th response in the control of genital HPV infections.

Expression of the human papillomavirus type 11 L1 capsid protein in Escherichia coli: characterization of protein domains involved in DNA binding and capsid assembly

The L1 major capsid protein of human papillomavirus type 11 (HPV-11) was expressed in Escherichia coli, and the soluble recombinant protein was purified to near homogeneity. The recombinant L1 protein bound DNA as determined by the Southwestern assay method, and recombinant mutant L1 proteins localized the DNA-binding domain to the carboxy-terminal 11 amino acids of L1. Trypsin digestion of the full-length L1 protein yielded a discrete 42-kDa product (trpL1), determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, resulting from cleavage at R415, 86 amino acids from the L1 carboxy terminus. Sucrose gradient sedimentation analysis demonstrated that trpL1 sedimented at 11S, while L1 proteins with amino-terminal deletions of 29 and 61 residues sedimented at 4S. Electron microscopy showed that the full-length L1 protein appeared as pentameric capsomeres which self-assembled into capsid-like particles. The trpL1 protein also had a pentameric morphology but was unable to assemble further. In an enzyme-linked immunosorbent assay, the trpL1 and L1 capsids reacted indistinguishably from virus-like particles purified after expression of HPV-11 L1 in insect cells. The carboxy terminus of L1 therefore constitutes the interpentamer linker arm responsible for HPV-11 capsid formation, much like the carboxy-terminal domain of the polyomavirus VP1 protein. The trypsin susceptibility of HPV-11 L1 capsids suggests a possible mechanism for virion disassembly.

Age distribution of antibodies to human papillomavirus in children, women with cervical intraepithelial neoplasia and blood donors from South Africa

Sera from 95 women with cervical intraepithelial neoplasia (CIN), 95 age-matched female blood donors, and 155 children aged between 1 and 12 years were tested by enzyme-linked immunosorbent assay (ELISA) for levels of serum IgG to three human papillomavirus (HPV) peptides (HPV-16 E2 [E2-16], HPV-18 E2 (E2-18], HPV-16 L1 [L1-16]), as well as HPV-16 virus-like particles (VLP-16) and bovine papillomavirus type 1 virus-like particles (BPV-VLP). In the adult group antibodies to E2-16 and VLP-16 were significantly associated with CIN when compared to the blood donor controls (P = .039 and P = .002, respectively). In women with CIN there was an increase in seropositivity to E2-16 and a decrease in seropositivity to VLP-16 with age. Antibodies to HPV-16 E2 could therefore be an important marker of CIN in women over 40 years of age, whereas antibodies to VLP-16 could be a marker for CIN in younger women. There was no correlation with CIN and antibodies to E2-18, L1-16, and BPV-VLP. In the children's sera antibodies were detected to E2-16 (44.5%), E2-18 (18.7%), L1-16 (20%), VLP-16 (4.5%), and BPV-VLP (5.1%). Between the ages of 3 and 12 years the prevalence of antibodies to E2-16 decreased with age. The presence of antibodies to HPV-16 in young children indicated infection with either HPV-16 or a related virus. HPV DNA isolation from children could help resolve this question.

Infection control to quality improvement: the right time, the right place, the work to be done

Many infection control epidemiologists are moving into the quality improvement field. The marriage of epidemiology with quality improvement is a logical step. Several things have to happen for this union to be successful, however. Most importantly, collaborative relationships must be forged with a variety of healthcare providers and practical, reliable, and valid indicators, and the methods for measuring them must be developed. This will take time, but epidemiologists should insist on and support the development of a robust discipline that combines the best of both worlds.

An apparatus for ultraviolet B irradiation of small volumes of biological fluid under controlled oxygen tension

BACKGROUND

The design, construction, and calibration of a unique apparatus for ultraviolet (UV) B irradiation of small volumes of biological fluid under temperature-controlled open atmospheric or closed cell conditions of defined Po2 is described.

METHODS

The apparatus consists of a custom designed UV transmissible quartz silica 3 port spectrophotometric cuvette coupled to a deuterium UV B source by UV transmissible fiber optics. Fluid movement, temperature regulation, dosimetry, and miniaturized biosensors for oxygen, pH, and temperature are described along with a preliminary experiment.

RESULTS

The apparatus produces a known photochemical effect using an endogenous aqueous humor UV B photosensitizer-L tryptophan. UV B radiation is contained, thus protecting laboratory personnel. The system provides a continuous spectral UV B dose of 30 mJ/cm2/hr, which is equivalent to approximately 5.5 UV sunlight hours reaching an aliquot of mammalian aqueous humor.

CONCLUSIONS

This biophysical apparatus can be used to investigate antioxidant protective systems in ocular fluid (aqueous/vitreous humors and tears), and is also applicable to evaluating the interaction of radiation with ocular and nonocular tissue cell homogenate.

Intestinal absorption of water-soluble vitamins

Vitamin utility is a scientific/medical topic that appears to be pursued as ardently by the lay public as by scientists and medical practitioners. A group of epidemiologists evaluates the effects on health of vitamin intake in the natural diet and by supplementation. The role in ocular disease, cancer of the breast or colon, and cardiovascular disease are a few of the concerns. The results and recommendations concerning dietary vitamin intake will likely continue to change. However, the processes by which dietary vitamins are delivered from intestinal chyme to the blood are more certain. The concept of homeostasis might apply to various of the vitamins as it does to minerals, water, etc. This review will discuss some common methods used to study vitamin absorption and the proposed mechanisms of absorption, and will conclude with a section about dietary regulation.

The potential role of speech production models in automatic speech recognition

This paper investigates the issues that are associated with applying speech production models to automatic speech recognition (ASR). Here the applicability of articulatory representations to ASR is considered independently of the role of articulatory representations in speech perception. While the question of whether it is necessary or even possible for human listeners to recover the state of the articulators during the process of perceiving speech is an important one, it is not considered here. Hence, the authors refrain from posing completely new paradigms for ASR which more closely parallel the relationship between speech production and human speech understanding. Instead, work aimed at integrating speech production models into existing ASR formalisms is described.