Mucosal immunisation with papillomavirus virus-like particles elicits systemic and mucosal immunity in mice

It has been shown previously that recombinant virus-like particles (VLPs) of papillomavirus can induce VLP-specific humoral and cellular immune responses following parenteral administration. To test whether mucosal administration of bovine papillomavirus type 1 (BPV1) VLPs could produce mucosal as well as systemic immune responses to VLPs, 50 mu g chimeric BPV1 VLPs containing an HPV16 E7 CTL epitope (BPVL1/E7 VLP) was administered intranasally to mice. After two immunisations, L1-specific serum IgG and IgA were observed. L1-specific IgG and IgA were also found in respiratory and vaginal secretions. Both serum and mucosal antibody inhibited papillomavirus VLP-induced agglutination of RBC, indicating that the antibody induced by mucosal immunisation may recognize conformational determinants associated with virus neutralisation. For comparison, VLPs were given intramuscularly, and systemic and mucosal immune responses were generally comparable following systemic or mucosal delivery. However, intranasal administration of VLP induced significantly higher local IgA response in lung, suggesting that mucosally delivered HPV VLP may be more effective for mediating local mucosal immune responses. Intranasal immunisation with HPV6b L1 VLP produced VLP-specific T proliferative responses in splenocytes, and immunisation with BPVL1 VLP containing an HPV16 E7 CTL epitope induced E7-specific CTL responses. We conclude that immunisation with papillomavirus VLPs via mucosal and intramuscular routes, without adjuvant, can elicit specific antibody at mucosal surfaces and also systemic VLP epitope specific T cell responses. These findings suggest that mucosally delivered VLPs may offer an alternative HPV VLP vaccine strategy for inducing protective humoral immunity to anogenital HPV infection, together with cell-mediated immune responses to eliminate any cells which become infected. (C) 1998 Academic Press.

Potential strategies utilised by papillomavirus to evade host immunity

The co-evolution of papillomaviruses (PV) and their mammalian hosts has produced mechanisms by which PV might avoid specific and non-specific host immune responses. Low level expression of PV proteins in infected basal epithelial cells, together with an absence of inflammation and of virus-induced cell lysis, restricts the opportunity for effective PV protein presentation to immunocytes by dendritic cells. Additionally, PV early proteins, by a range of mechanisms, may restrict the efficacy of antigen presentation by these cells. Should an immune response be induced to PV antigens, resting keratinocytes (KC) appear resistant to interferon-gamma-enhanced mechanisms of cytotoxic T-lymphocyte (CTL)-mediated lysis, and expression of PV antigens by resting KC can tolerise PV-specific CTL. Thus, KC, in the absence of inflammation, may represent an immunologically privileged site for PV infection. Together, these mechanisms play a parr in allowing persistence of PV-induced proliferative skin lesions for months to years, even in immunocompetent hosts.

Human and murine cytomegalovirus evasion of cytotoxic T lymphocyte and natural killer cell-mediated immune responses

Herpesviruses, such as human and murine cytomegalovirus, possess an impressive array of genes believed to assist in virus survival against the host immune response. In this review, we cover the rapidly growing area of cytomegalovirus evasion of cellular immunity, specifically cytotoxic T lymphocytes and natural killer cells. The proposed mechanisms of action of viral proteins involved in blocking peptide presentation to CD8(+) T cells, namely, interference with peptide generation, inhibition of peptide assembly with class I MHC and retention/destabilization of class I MHC complexes, are described. In addition, recent evidence implicating the viral class I MHC-like proteins as inhibitors of natural killer cell-mediated clearance is reviewed, (C) 1998 Academic Press.

GABA receptors inhibited by benzodiazepines mediate fast inhibitory transmission in the central amygdala

The amygdala is intimately involved in emotional behavior, and its role in the generation of anxiety and conditioned fear is well known. Benzodiazepines, which are commonly used for the relief of anxiety, are thought to act by enhancing the action of the inhibitory transmitter GABA. We have examined the properties of GABA-mediated inhibition in the amygdala. Whole-cell recordings were made from neurons in the lateral division of the central amygdala. Application of GABA evoked a current that reversed at the chloride equilibrium potential. Application of the GABA antagonists bicuculline or SR95531 inhibited the GABA-evoked current in a manner consistent with two binding sites. Stimulation of afferents to neurons in the central amygdala evoked an IPSC that was mediated by the release of GABA. The GABA(A) receptor antagonists bicuculline and picrotoxin failed to completely block the IPSC. The bicuculline-resistant IPSC was chloride-selective and was unaffected by GABA(B)-receptor antagonists. Furthermore, this current was insensitive to modulation by general anesthetics or barbiturates. In contrast to their actions at GABA(A) receptors, diazepam and flurazepam inhibited the bicuculline-resistant IPSC in a concentration-dependent manner. These effects were fully antagonized by the benzodiazepine site antagonist Ro15-1788. We conclude that a new type of ionotropic GABA receptor mediates fast inhibitory transmission in the central amygdala. This receptor may be a potential target for the development of new therapeutic strategies for anxiety disorders.

Adhesion of microbes using 3-aminopropyl triethoxy silane and specimen stabilisation techniques for analytical transmission electron microscopy

A variety of adhesive support-films were tested for their ability to adhere various biological specimens for transmission electron microscopy. Support films primed with 3-amino-propyl triethoxy silane (APTES), poly-L-lysine, carbon and ultraviolet-B (UV-B)-irradiated carbon were tested for their ability to adhere a variety of biological specimens including axenic cultures of Bacillus subtilis and Escherichia coli and wild-type magnetotactic bacteria. The effects of UV-B irradiation on the support film in the presence of air and electrostatic charge on primer deposition were tested and the stability of adhered specimens on various surfaces was also compared. APTES-primed UV-B-irradiated Pioloform(TM) was consistently the best adhesive, especially for large cells, and when adhered specimens were UV-B irradiated they became remarkably stable under an electron beam. This assisted the acquisition of in situ phase-contrast lattice images from a variety of biominerals in magnetotactic bacteria, in particular metastable greigite magnetosomes. Washing tests indicated that specimens adhering to APTES-primed UV-B-irradiated Pioloform(TM) were covalently coupled. The electron beam stability was hypothesised to be the result of mechanical strengthening of the specimen and support film and the reduced electrical resistance in the specimen and support film due to their polymerization and covalent coupling.

Glutamate-mediated transmission, alcohol, and alcoholism

Glutamate-mediated neurotransmission may be involved in the range of adaptive changes in brain which occur after ethanol administration in laboratory animals, and in chronic alcoholism in human cases. Excitatory amino acid transmission is modulated by a complex system of receptors and other effecters, the efficacy of which can be profoundly affected by altered gene or protein expression. Local variations in receptor composition may underlie intrinsic regional variations in susceptibility to pathological change. Equally, ethanol use and abuse may bring about alterations in receptor subunit expression as the essence of the adaptive response. Such considerations may underlie the regional localization characteristic of the pathogenesis of alcoholic brain damage, or they may form part of the homeostatic change that constitutes the neural substrate for alcohol dependence. (C) 2000 Elsevier Science Ltd. All rights reserved.

Transmission of ocular media in labrid fishes

Wrasses (Labridae) are the second largest family of fishes on the: Great Barrier Reef (after the Gobiidae) and, in terms of morphology and lifestyle, one of the most diverse. They occupy all zones of the reef from the very shadow reef flats to deep slopes, feeding on a variety of fauna. Many wrasses also have elaborately patterned bodies and reflect a range of colours from ultraviolet (UV) to far red. As a first step to investigating the visual system of these fishes we measured the transmission properties of the ocular media of 36 species from the Great Barrier Reef, Australia, and Hawaii, California and the Florida Keys, USA. Transmission measurements were made of whole eyes with a window cut into the back, and also of isolated lenses and corneas. Based on the transmission properties of the corneas the species could be split into two distinct groups within which the exact wavelength of the cut-off was variable. One group had visibly yellow corneas, while the corneas of the other group appeared clear to human observers. Five species had ocular media that transmitted wavelengths below 400 nm, making a perception of UV wavelengths for those species possible. Possible functional roles for the different filler types are discussed.

Multiple conformational epitopes are recognized by natural and induced immunity to the E7 protein of human papilloma virus type 16 in man

The reactivity of sera from patients with cervical cancer with the E7 protein of human papilloma virus type 16 (HPV16) was estimated using a novel non-radioactive immunoprecipitation assay and four established protein-and peptide-based immunoassays. Six of 14 sera from patients with cervical cancer and 1 of 10 sera from healthy laboratory staff showed repeated reactivity with E7 in at least one assay. Four of the 7 reactive sera were consistently reactive in more than one assay, but only one was reactive in all four assays. Following immunization with E7, 2 of 5 patients with cervical cancer had increased E7-specific reactivity, measurable in one or more assays. No single assay was particularly sensitive for E7 reactivity, or predictive of cervical cancer. Mapping of E7 reactivity to specific E7 peptides was unsuccessful, suggesting that natural or induced E7 reactivity in human serum is commonly directed to conformational epitopes of E7, These results suggest that each assay employed with is study measures a different aspect of E7 reactivity, and that various reactivities to E7 may manifest following HPV infection or immunization. This finding is of significance for monitoring of E7 immunotherapy and for serological screening for cervical cancer. Copyright (C) 2000 S.Karger, AG. Basel.

The anti-tumor activity of IL-12: Mechanisms of innate immunity that are model and dose dependent

IL-12 has been demonstrated to have potent anti-tumor activities in a variety of mouse tumor models, but the relative roles of NK, NKT, and T cells and their effector mechanisms in these responses have not been fully addressed. Using a spectrum of gene-targeted or Ab-treated mice we have shown that for any particular tumor model the effector mechanisms downstream of IL-12 often mimic the natural immune response to that tumor. For example, metastasis of the MHC class I-deficient lymphoma, EL4-S3, was strictly controlled by NK cells using perforin either naturally or following therapy with high-dose IL-12. Intriguingly, in B16F10 and RM-1 tumor models both NK and NKT cells contribute to natural protection from tumor metastasis, In these models, a lower dose of IL-12 or delayed administration of IL-12 dictated a greater relative role of NKT cells in immune protection from tumor metastasis. Overall, both NK and NKT cells can contribute to natural and IL-12-induced immunity against tumors, and the relative role of each population is turner and therapy dependent.

CD40 ligation conditions dendritic cell antigen-presenting function through sustained activation of NF-kappa B

An understanding of the biochemical control of dendritic cell (DC) differentiation/activation is essential for improving T cell immunity by various immunotherapeutic approaches, including DC immunization. Ligation of CD40 enhances DC function, including conditioning for CTL priming. NF-kappaB, and particularly RelB, is an essential control pathway for myeloid DC differentiation. Furthermore, RelB regulates B cell Ag-presenting function. We hypothesized that CD40 ligand (CD40L) and TNF-alpha, which differ in their capacity to condition DC, would also differ in their capacity to activate NF-kappaB. DC differentiated for 2 days from monocytes in the presence of GM-CSF and IL-4 were used as a model, as NF-kappaB activity was constitutively low. The capacity of DC to activate T cells following CD40L treatment was enhanced compared with TNF-alpha treatment, and this was NF-kappaB dependent. Whereas RelB/p50 translocation induced by TNF-alpha was attenuated after 6 h, RelB/p50 nuclear translocation induced by CD40L was sustained for at least 24 h. The mechanism of this difference related to enhanced degradation of IkappaBalpha following CD40L stimulation. However, NF-kappaB activation induced by TNF-alpha could be sustained by blocking autocrine IL-10. These data indicate that NF-kappaB activation is essential for T cell activation by DC, and that this function is enhanced if DC NF-kappaB activation is prolonged. Because IL-10 moderates DC NF-kappaB activation by TNF-alpha, sustained NF-kappaB activation can be achieved by blocking IL-10 in the presence of stimuli that induce TNF-alpha.

The role of dogs in transmission of gastrointestinal parasites in a remote tea-growing community in northeastern India

The prevalence and risk factors associated with canine gastrointestinal parasitic zoonoses and the role of dogs in the mechanical transmission of human Ascaris infection was examined in three tea estates in Assam, India. Nearly all (99%) dogs harbored one or more zoonotic species of gastrointestinal parasites, with hookworm infection being most common (94%). Parasitic stages presumed to be host-specific for humans such as Ascaris spp. (31%), Trichuris trichiura (25%), and Isospora belli (2%) were also recovered from dog feces. A polymerase chain reaction-linked restriction fragment length polymorphism technique was used to differentiate the species of Ascaris eggs in dog feces. The results of this study demonstrate the role of the dog as a significant disseminator and environmental contaminator of Ascaris lumbricoides in communities where promiscuous defecation by humans occurs.

Excitatory synaptic transmission in the lateral and central amygdala

The amygdala plays a major role in the acquisition and expression of fear conditioning. NMDA receptor-dependent synaptic plasticity within the basolateral amygdala has been proposed to underlie the acquisition and possible storage of fear memories. Here the properties of fast glutamatergic transmission in the lateral and central nuclei of the amygdala are presented. In the lateral amygdala, two types of neurons, interneurons and projection neurons, could be distinguished by their different firing properties. Glutamatergic inputs to interneurons activated AMPA receptors with inwardly rectifying current-voltage relations (I-Vs), whereas inputs to projection neurons activated receptors that had linear I-Vs, indicating that receptors on interneurons lack GluR2 subunits. Inputs to projection neurons formed dual component synapses with both AMPA and NMDA components, whereas at inputs to interneurons, the contribution of NMDA receptors was very small. Neurons in the central amygdala received dual component glutamatergic inputs that activated AMPA receptors with linear I-Vs. NMDA receptor-mediated EPSCs had slow decay time constants in the central nucleus. Application of NR2B selective blockers ifenprodil or CP-101,606 blocked NMDA EPSCs by 70% in the central nucleus, but only by 30% in the lateral nucleus. These data show that the distribution of glutamatergic receptors on amygdalar neurons is not uniform. In the lateral amygdala, interneurons and pyramidal neurons express AMPA receptors with different subunit compositions. Synapses in the central nucleus activate NMDA receptors that contain NR1 and NR2B subunits, whereas synapses in the lateral nucleus contain receptors with both NR2A and NR2B subunits.

Altered inhibitory synaptic transmission in superficial dorsal horn neurones in spastic and oscillator mice

The spastic (spa) and oscillator (ot) mouse have naturally occurring mutations in the inhibitory glycine receptor (GlyR) and exhibit severe motor disturbances when exposed to unexpected sensory stimuli. We examined the effects of the spa and ot mutations on GlyR- and GABA(A)R-mediated synaptic transmission in the superficial dorsal horn (SFDH), a spinal cord region where inhibition is important for nociceptive processing. Spontaneous mIPSCs were recorded from visually identified neurones in parasagittal spinal cord slices. Neurones received exclusively GABA(A)R-mediated mIPSCs, exclusively GlyR-mediated mIPSCs or both types of mIPSCs. In control mice (wild-type and spa/+) over 40 % of neurones received both types of mIPSCs, over 30 % received solely GABA(A)R-mediated mIPSCs and the remainder received solely GlyR-mediated mIPSCs. In spa/spa animals, 97 % of the neurones received exclusively GABA(A)ergic or both types of mIPSCs. In ot/ot animals, over 80 % of the neurones received exclusively GABA(A)R-mediated mIPSCs. GlyR-mediated mIPSC amplitude and charge were reduced in spa/spa and ot/ot animals. GABA,Rmediated mIPSC amplitude and charge were elevated in spa/spa but unaltered in ot/ot animals. GlyR- and GABA(A)R-mediated mIPSC decay times were similar for all genotypes, consistent with the mutations altering receptor numbers but not kinetics. These findings suggest the spastic and oscillator mutations, traditionally considered motor disturbances, also disrupt inhibition in a sensory region associated with nociceptive transmission. Furthermore, the spastic mutation results in a compensatory increase in GABA(A)ergic transmission in SFDH neurones, a form of inhibitory synaptic plasticity absent in the oscillator mouse.