Whole-Genome Sequencing-Based Confirmatory Methods on RT-qPCR Results for the Detection of Foodborne Viruses in Frozen Berries

Accurate detection, identification, and subsequent confirmation of pathogens causing foodborne illness are essential for the prevention and investigation of foodborne outbreaks. This is particularly true when the causative agent is an enteric virus that has a very low infectious dose and is likely to be present at or near the limit of detection. In this study, whole-genome sequencing (WGS) was combined with either of two non-targeted pre-amplification methods (SPIA and SISPA) to investigate their utility as a confirmatory method for RT-qPCR positive results of foods contaminated with enteric viruses. Frozen berries (raspberries, strawberries, and blackberries) were chosen as the food matrix of interest due to their association with numerous outbreaks of foodborne illness. The hepatitis A virus (HAV) and human norovirus (HuNoV) were used as the contaminating agents. The non-targeted WGS strategy employed in this study could detect and confirm HuNoV and HAV at genomic copy numbers in the single digit range, and in a few cases, identified viruses present in samples that had been found negative by RT-qPCR analyses. However, some RT-qPCR-positive samples could not be confirmed using the WGS method, and in cases with very high Ct values, only a few viral reads and short sequences were recovered from the samples. WGS techniques show great potential for confirmation and identification of virally contaminated food items. The approaches described here should be further optimized for routine application to confirm the viral contamination in berries.

Challenges for estimating human norovirus infectivity by viability RT-qPCR as compared to replication in human intestinal enteroids

Viability RT-qPCR, a molecular detection method combining viability marker pre-treatment with RT-qPCR, has been proposed to infer infectivity of viruses which is particularly relevant for non-culturable viruses or sophisticated cell culture systems. Being human noroviruses (HuNoV) most frequently associated with foodborne outbreaks, this study compared different viability techniques and infectivity in human intestinal enteroids (HIE) to ultimately determine whether the molecular approaches could serve as rapid assays to predict HuNoV inactivation in high-risk food. To this end, the performance of three viability RT-qPCR assays with different intercalating markers ((Viability PCR Crosslinker Kit (CL), propidium monoazide (PMAxx™), and platinum chloride (PtCl4)) in estimating survival of HuNoV exposed to thermal and high pressure (HPP) treatments was compared to replication tested in the HIE cell culture model. A nearly full-length genomic molecular assay coupled with PMAxx™ to infer HuNoV thermal inactivation was also assessed. The experimental design included HuNoV genogroup I.3 [P13], GII.4 Sydney [P16], GII.6 [P7], along with Tulane virus (TV) serving as surrogate. Finally, viability RT-qPCR was tested in HPP-treated strawberry puree, selected as a food matrix with high viral contamination risk. PMAxx™ and CL performed evenly, while PtCl4 affected HuNoV infectivity. Taking all experimental data together, viability RT-qPCR was demonstrated to be an improved method over direct RT-qPCR to estimate viral inactivation at extreme thermal (95 °C) and HPP (450 MPa) exposures, but not under milder conditions as amplification signals were detected. Despite its complexity and limitations, the HIE demonstrated a more robust model than viability RT-qPCR to assess HuNoV infectivity.

Use of Human Intestinal Enteroids for Recovery of Infectious Human Norovirus from Berries and Lettuce

Norovirus (NoV) is the leading cause of viral foodborne gastroenteritis globally. Currently, the gold standard for detecting NoV in clinical, food, and environmental samples is via molecular-based methods, primarily RT-PCR. Nevertheless, there is a great need for confirmatory assays that can determine the infectivity of viral particles recovered from contaminated matrices. The use of the human intestinal enteroids system (HIEs) has allowed for the expansion of norovirus replication, although it still suffers from limitations of strain preferences and the requirement of high titer stocks for infection. In this study, we wanted to explore the feasibility of using the HIEs to support the replication of NoV that had been recovered from representative food matrices that have been associated with foodborne illness. We first confirmed that HIEs can support the replication of several strains of NoV as measured by RT-qPCR. We subsequently chose two of those strains that reproducibly replicated, GII.4 and GII.6, to evaluate in a TCID50 assay and for future experiments. Infectious NoV could be recovered and quantified in the HIEs from lettuce, frozen raspberries, or frozen strawberries seeded with high titers of either of these strains. While many experimental challenges still remain to be overcome, the results of this study represent an important step toward the detection of infectious norovirus from representative produce items.

Evaluation of U.S. Food and Drug Administration Enteric Viruses Microarray for Detection of Hepatitis A Virus and Norovirus in Inoculated Tomatoes, Green Onions, and Celery

ABSTRACT

Foodborne viral contamination of fresh produce has been associated with numerous outbreaks. Detection of such contaminated foods is important in protecting public health. Here, we demonstrate for the first time the capability of the U.S. Food and Drug Administration Enteric Viruses tiling microarray (FDA-EVIR) to perform rapid molecular identification of hepatitis A virus (HAV) and human norovirus extracted from artificially inoculated fresh produce. Two published viral extraction strategies, total RNA extraction or virus particle isolation, were used to prepare the viral targets. The total RNA extraction method was used on material eluted from tomatoes, using an alkaline Tris-glycine-beef extract (TGBE) buffer. Optimization procedures including DNase treatment and poly(A)-RNA enrichment were adopted to improve microarray sensitivity. For green onions or celery, material was eluted using either glycine buffer or TGBE buffer supplemented with pectinase, respectively, and then virus particles were concentrated by ultracentrifugation. We also assessed the amount of viral RNA extracted from celery using three commercially available kits and how well that RNA performed on FDA-EVIR. Our results confirm that FDA-EVIR can identify common enteric viruses isolated from fresh produce when present as either a single or mixed species of viruses. Using total RNA extraction from tomatoes yielded a limit of detection of 1.0 × 105 genome equivalents (ge) of HAV per array input. The limit of detection for viral RNA obtained using ultracentrifugation was 1.2 × 105 ge of HAV from green onions and 1.0 × 103 ge of norovirus from celery per array input. Extending microarray methods to other food matrices should provide important support to surveillance and outbreak investigations.

HIGHLIGHTS

Severe acute respiratory syndrome coronavirus 2 may be an underappreciated pathogen of the central nervous system

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) causes a highly contagious respiratory disease referred to as COVID‐19. However, emerging evidence indicates that a small but growing number of COVID‐19 patients also manifest neurological symptoms, suggesting that SARS‐CoV‐2 may infect the nervous system under some circumstances. SARS‐CoV‐2 primarily enters the body through the epithelial lining of the respiratory and gastrointestinal tracts, but under certain conditions this pleiotropic virus may also infect peripheral nerves and gain entry into the central nervous system (CNS). The brain is shielded by various anatomical and physiological barriers, most notably the blood–brain barrier (BBB) which functions to prevent harmful substances, including pathogens and pro‐inflammatory mediators, from entering the brain. The BBB is composed of highly specialized endothelial cells, pericytes, mast cells and astrocytes that form the neurovascular unit, which regulates BBB permeability and maintains the integrity of the CNS. In this review, potential routes of viral entry and the possible mechanisms utilized by SARS‐CoV‐2 to penetrate the CNS, either by disrupting the BBB or infecting the peripheral nerves and using the neuronal network to initiate neuroinflammation, are briefly discussed. Furthermore, the long‐term effects of SARS‐CoV‐2 infection on the brain and in the progression of neurodegenerative diseases known to be associated with other human coronaviruses are considered. Although the mechanisms of SARS‐CoV‐2 entry into the CNS and neurovirulence are currently unknown, the potential pathways described here might pave the way for future research in this area and enable the development of better therapeutic strategies.

Serum paraoxonase 1 activity and lipid metabolism parameter changes in Dachshunds with chronic mitral valve disease. Assessment of its diagnostic usefulness

Chronic mitral valve disease, which is frequently diagnosed in Dachshunds, leads to structural, hemodynamic and redox state changes in dogs. The aim of this study was to investigate serum paraoxonase 1 (PON1) activity and lipid metabolism in different disease stages. Standardized PON1 activity (PON1/HDL ratio) was lower in asymptomatic dogs, B1 and B2 Stages when compared to healthy ones and symptomatic Dachshunds in Stage C (ACVIM classfication). PON1 paraoxonase activity was elevated in Stage C dogs, with no changes found in PON1 activity towards phenyl acetate. Dachshunds in Stage B2 and C showed increased triglyceride levels, with no changes in cholesterol and lipoprotein concentration in comparison to healthy ones. Our data suggest that standardized PON1 activity changes could be used in laboratory diagnostics to differentiate the CMVD of affected asymptomatic (Stage B1 and B2) dogs from healthy (Stage A) and clinically affected (Stage C) dogs. Also, a standardized PON1 activity increase might be a prognostic progression signal of the disease to Stage C.

Cysteinyl leukotrienes C4 and D4 downregulate human mast cell expression of toll-like receptors 1 through 7

Cysteinyl leukotrienes (CysLT) are potent inflammatory lipid molecules that mediate some of the pathophysiological responses associated with asthma such as bronchoconstriction, vasodilation and increased microvascular permeability. As a result, CysLT receptor antagonists (LRA), such as montelukast, have been used to effectively treat patients with asthma. We have recently shown that mast cells are necessary modulators of innate immune responses to bacterial infection and an important component of this innate immune response may involve the production of CysLT. However, the effect of LRA on innate immune receptors, particularly on allergic effector cells, is unknown. This study determined the effect of CysLT on toll-like receptor (TLR) expression by the human mast cell line LAD2. Real-time PCR analysis determined that LTC4, LTD4 and LTE4 downregulated mRNA expression of several TLR. Specifically in human CD34+-derived human mast cells (HuMC), LTC4 inhibited expression of TLR1, 2, 4, 5, 6 and 7 while LTD4 inhibited expression of TLR1-7. Montelukast blocked LTC4-mediated downregulation of all TLR, suggesting that these effects were mediated by activation of the CysLT1 receptor (CysLT1R). Flow cytometry analysis confirmed that LTC4 downregulated surface expression of TLR2 which was blocked by montelukast. These data show that CysLT can modulate human mast cell expression of TLR and that montelukast may be beneficial for innate immune responses mediated by mast cells.

Testing for Human Norovirus and Recovery of Process Control in Outbreak-Associated Produce Items

The development of rapid and sensitive detection methods for human noroviruses (HuNoV) in produce items is critical, especially with the recent rise in outbreaks associated with this food commodity. In this study, 50-g portions of various produce items linked to a norovirus outbreak (celery, cucumber, lettuce, grapes, and radish) were artificially inoculated with murine norovirus (MNV-1) and concentrated either by ultracentrifugation or polyethylene glycol (PEG) precipitation after elution with an alkaline Tris-glycine-beef extract buffer supplemented with pectinase. As a viral concentration step following virus elution and clarification, ultracentrifugation yielded a faster method (<8 h, including reverse transcription quantitative PCR), with MNV-1 recoveries similar to or better, than those obtained with PEG precipitation. The addition of polyvinylpyrrolidone to the elution buffer, to remove polyphenolic inhibitors, improved MNV-1 recoveries by over two- and fivefold for cucumber and grapes, respectively. However, despite MNV-1 recoveries ranging from 10 to 38% as calculated with 10-fold diluted RNA, contaminating HuNoV was not detected in any of the outbreak-associated samples tested. For store-bought produce samples, the limit of detection for artificially seeded HuNoV GII.4 was determined to be 103 copies per 50 g, with reproducible detection achieved in grapes, radish, and celery. The results support the use of ultracentrifugation as an alternative approach to PEG precipitation to concentrate norovirus from a variety of produce items.

Human Gut-On-A-Chip Supports Polarized Infection of Coxsackie B1 Virus In Vitro

Analysis of enterovirus infection is difficult in animals because they express different virus receptors than humans, and static cell culture systems do not reproduce the physical complexity of the human intestinal epithelium. Here, using coxsackievirus B1 (CVB1) as a prototype enterovirus strain, we demonstrate that human enterovirus infection, replication and infectious virus production can be analyzed in vitro in a human Gut-on-a-Chip microfluidic device that supports culture of highly differentiated human villus intestinal epithelium under conditions of fluid flow and peristalsis-like motions. When CVB1 was introduced into the epithelium-lined intestinal lumen of the device, virions entered the epithelium, replicated inside the cells producing detectable cytopathic effects (CPEs), and both infectious virions and inflammatory cytokines were released in a polarized manner from the cell apex, as they could be detected in the effluent from the epithelial microchannel. When the virus was introduced via a basal route of infection (by inoculating virus into fluid flowing through a parallel lower 'vascular' channel separated from the epithelial channel by a porous membrane), significantly lower viral titers, decreased CPEs, and delayed caspase-3 activation were observed; however, cytokines continued to be secreted apically. The presence of continuous fluid flow through the epithelial lumen also resulted in production of a gradient of CPEs consistent with the flow direction. Thus, the human Gut-on-a-Chip may provide a suitable in vitro model for enteric virus infection and for investigating mechanisms of enterovirus pathogenesis.

Optimizing a custom tiling microarray for low input detection and identification of unamplified virus targets

Viruses are major pathogens causing foodborne illnesses and are often present at low levels in foods, thus requiring sensitive techniques for their detection in contaminated foods. The lack of efficient culture methods for many foodborne viruses and the potential for multi-species viral contamination have driven investigation toward non-amplification based methods for virus detection and identification. A custom DNA microarray (FDA_EVIR) was assessed for its sensitivity in the detection and identification of low-input virus targets, human hepatitis A virus, norovirus, and coxsackievirus, individually and in combination. Modifications to sample processing were made to accommodate low input levels of unamplified virus targets, which included addition of carrier cDNA, RNase treatment, and optimization of DNase I-mediated target fragmentation. Amplification-free detection and identification of foodborne viruses were achieved in the range of 250-500 copies of virus RNA. Alternative data analysis methods were employed to distinguish the genotypes of the viruses particularly at lower levels of target input and the single probe-based analysis approach made it possible to identify a minority species in a multi-virus complex. The oligonucleotide array is shown to be a promising platform to detect foodborne viruses at low levels close to what are anticipated in food or environmental samples.

Serum paraoxonase 1 (PON1) activity and lipid metabolism parameters changes in different production cycle periods of Holstein-Friesian, Polish Red and Norwegian breeds

We investigated the measurement of paraoxonase 1 (PON1), as a potential marker of redox state changes in dairy cows, its involvement in lipid metabolism and compared it with superoxide dismutase (SOD) activity changes. We also evaluated lipid metabolism parameters associated with dairy production. PON1 paraoxonase and arylesterase acitvities, SOD activity, beta-hydroxybutyrate (BHB), uric acid (UA), high density lipoprotein (HDL), low density lipoprotein (LDL), cholesterol and triglyceride concentrations were measured in Holstein-Friesian, Polish Red and Norwegian breeds serum in two production cycles. Our data showed a significant postpartum depletion in PON1 activity and lipoprotein and lipid products concentrations, with elevated BHB values. However, there were no significant changes in SOD activity and uric acid concentrations in Holstein-Friesian and Polish Red breeds after calving. At lactation peak there was a significant SOD activity decrease correlated with standardized PON1 activity depletion in all examined breeds. The results suggest that PON1 might be a better parameter for minimal redox state changes in serum, shortly after labour in the examined breeds.

A review of paraoxonase 1 properties and diagnostic applications

Paraoxonase 1 (PON1) is an arylesterase associated with serum high density lipoprotein particles. Its name is derived from hydrolyzing one of several organophosphate compounds, namely paraoxon. Recent studies have shown that PON1 plays a protective role in diseases associated with oxidative stress such as atherosclerosis and diabetes mellitus. Studies have demonstrated reduction-oxidative state changes involving PON1 in humans and laboratory animal models. Although there is less information about the role of this enzyme in veterinary medicine, new data suggest that PON1 might be a new oxidative stress marker in animal patients, similarly to humans.

A novel eremophilane lactone inhibits FcεRI-dependent release of pro-inflammatory mediators: structure-dependent bioactivity

BACKGROUND

Allergic inflammation is primarily mediated by immune effector cells such as mast cells and basophils that release proinflammatory cytokines. Both mast cells and basophils are activated via their high affinity IgE receptor (FcεRI) which initiates the release of proinflammatory mediators such as histamine and tumor necrosis factor (TNF). Considerable effort has been focused on finding an effective basophil stabilizer that inhibits the activation of FcεRI-activated mediator release. Recently, eremophilane lactones, a novel family of sesquiterpene compound originally isolated from Petasites japonicas (Sieb. et Zucc.), have been described, and it has been postulated that they may have anti-inflammatory activity, particularly in allergic disease.

OBJECTIVE

Our objective was to determine the effect of two eremophilane lactones derived from 6β-angeloyloxy-3β,8-dihydroxyeremophil-7(11)-en-12,8β-olide (F-1) on immunoglobulin E (IgE)-dependent release of pro-inflammatory mediators by a basophil cell line, RBL-2H3, a model system for FcεRI-mediated activation of pro-inflammatory mediator release.

METHODS

The parent compound (F-1) was chemically modified to produce F-1a [6β-angeloyloxy-3β-benzoyloxy-8-hydroxyeremophil-7(11)-en-12,8β-olide] and F-1b [6β-angeloyloxy-3β,8-diacetoxyeremophil-7(11)-en-12,8β-olide]. RBL-2H3 cells were sensitized with DNP-specific IgE and then activated with DNP-BSA. The effect of these compounds on IgE-dependent basophil degranulation was assessed by measuring the release of β-hexosaminidase (b-hex). In addition, TNF release was measured via ELISA.

RESULTS

The phenylacetyl reaction modified C-8 and produced F-1a whereas acetylation of F-1 produced F-1b. F-1a was not cytotoxic to RBL-2H3 cells even at 50 μM, but F-1b was slightly cytotoxic at 50 μM, reducing viability of the cells by approximately 15 %. Neither F-1a nor F-1b inhibited FcεRI-dependent activation of RBL-2H3 cells when the cells were pretreated for only 30 min with the compounds. However, 24 h pretreatment with F-1a inhibited antigen-dependent degranulation by as much as 60 % and TNF production by as much as 90 %. F-1b had no effect on RBL-2H3 activation via FcεRI.

CONCLUSIONS

These results indicate that F-1a inhibits degranulation of RBL-2H3 cells activated via the high affinity IgE receptor, FcεRI, and that this effect is dependent upon hydroxylation of the third carbon.

Review: Approaches to the Viral Extraction, Detection, and Identification of Hepatitis Viruses, HAV and HEV, in Foods

Although the incidence rate of hepatitis A virus (HAV) infection has been on the decline in developed countries, in part due to immunization availability, high profile outbreaks continue to be reported. Hepatitis E virus has been recognized as an emerging pathogen in industrialized countries. While associated with waterborne illnesses, particularly in undeveloped countries, several animal species have been identified as reservoirs for the virus. Consequently, the potential of zoonotic transmission exists as a function of the consumption of infected animals. In this review we provide a comparative overview of these two virus species with regard to their known virus properties, discuss extraction methodologies, and describe some basic principles and methodology applied toward the isolation of these viruses (as particles or their isolated genomes) from food commodities. We also discuss the challenges that remain as experimental hurdles to extraction of such viruses from food. As HAV has been the most extensively studied with regard to virus detection in foods, it often serves as a model virus for current and future development of sample preparation methodology for foodborne virus detection. Lastly, we discuss the application and role of current and developing technologies in the post-extraction detection and identification of these viruses from foods.

Temperature and density dependent induction of a cytopathic effect following infection with non-cytopathic HAV strains

Hepatitis A virus infection and growth in cultured cells is protracted, cell-type restricted, and generally not accompanied by the appearance of a cytopathic effect, with the exception of some culture-adapted strains. We demonstrate that the non-cytopathic HAV strain HM175/clone 1 can be induced to exhibit a cytopathic phenotype in both persistently or acutely infected cells under co-dependent conditions of lower incubation temperature (<34°C) and reduced cell density in both monkey (FRhK-4) and human (A549) cells. This phenotype is not virus-strain restricted, as it was also observed in cells infected with HAV strains, HAS-15 and LSH/S. Cytopathic effect was accompanied by rRNA cleavage, indicating activation of the RNase L pathway, viral negative strand synthesis, caspase-3 activation, and apoptosis. The results indicate that a cytopathic phenotype may be present in some HAV strains that can be induced under appropriate conditions, suggesting the potential for development of a plaque assay for this virus.

Systemic fungicidal activity of 1,4-oxathiin derivatives

Treatment of pinto bean and barley seed with 1,4-oxathiin derivatives gave disease control by systemic fungicidal action of such pathogenic fungi as Uromyces phaseoli and Ustilago nuda. The two chemicals, D735 and F461, were highly specific and selective against the pathogens without injury of the hosts.

The potential of natural products as effective treatments for allergic inflammation: implications for allergic rhinitis

The impact of natural products on human health has been enormous, and the study of natural products continues to influence research in the fields of chemistry, biology, and ecology. Historically, the majority of our medicines originate from natural products and their synthetic derivatives, many of which have taught us valuable lessons about biology. While advances in synthetic and combinatorial chemistry have given rise to notable successes in the development of new drugs, the perceived value of natural products in the treatment of allergic disease has yet to be fully explored. The immune system is a highly complex, intricately regulated group of cells whose integrated function is essential to health. Cells of the immune system may interact in a cell-cell manner and may also respond to intercellular messages including hormones, cytokines, and effector molecules produced by various cells. These effector molecules include histamine, kinins, leukotrienes, prostaglandins, and serotonin. The immune system can be modified by diet, pharmacologic agents, environmental pollutants, and naturally occurring food chemicals, such as vitamins and flavonoids. Allergic inflammation is mediated by several types of immune cells all of which can be effected by these naturally occurring bioactive compounds but this review will focus on mast cells and their mediators since these cells are the focal point of allergic reactions such as allergic rhinitis. The molecular mechanisms and scientific validity of some herbal remedies currently used clinically in the treatment of allergic rhinitis will be explored.

Activation of the 2-5OAS/RNase L pathway in CVB1 or HAV/18f infected FRhK-4 cells does not require induction of OAS1 or OAS2 expression

The latent, constitutively expressed protein RNase L is activated in coxsackievirus and HAV strain 18f infected FRhK-4 cells. Endogenous oligoadenylate synthetase (OAS) from uninfected and virus infected cell extracts synthesizes active forms of the triphosphorylated 2-5A oligomer (the only known activator of RNase L) in vitro and endogenous 2-5A is detected in infected cell extracts. However, only the largest OAS isoform, OAS3, is readily detected throughout the time course of infection. While IFNbeta treatment results in an increase in the level of all three OAS isoforms in FRhK-4 cells, IFNbeta pretreatment does not affect the temporal onset or enhancement of RNase L activity nor inhibit virus replication. Our results indicate that CVB1 and HAV/18f activate the 2-5OAS/RNase L pathway in FRhK-4 cells during permissive infection through endogenous levels of OAS, but contrary to that reported for some picornaviruses, CVB1 and HAV/18f replication is insensitive to this activated antiviral pathway.

A microarray based approach for the identification of common foodborne viruses

An oligonucleotide array (microarray) incorporating 13,000 elements representing selected strains of hepatitis A virus (HAV), human coxsackieviruses A and B (CVA and CVB), genogroups I and II of Norovirus (NV), and human rotavirus (RV) gene segments 3,4,10, and 11 was designed based on the principle of tiling. Each oligonucleotide was 29 bases long, starting at every 5th base of every sequence, resulting in an overlap of 24 bases in two consecutive oligonucleotides. The applicability of the array for virus identification was examined using PCR amplified products from multiple HAV and CV strains. PCR products labeled with biotin were hybridized to the array, and the biotin was detected using a brief reaction with Cy3-labeled streptavidin, the array subjected to laser scanning, and the hybridization data plotted as fluorescence intensity against each oligonucleotide in the array. The combined signal intensities of all probes representing a particular strain of virus were calculated and plotted against all virus strains identified on a linear representation of the array. The profile of the total signal intensity identified the strain that is most likely represented in the amplified cDNA target. The results obtained with HAV and CV indicated that the hybridization profile thus generated can be used to identify closely related viral strains. This represents a significant improvement over current methods for virus identification using PCR amplification and amplicon sequencing.

Codeine induces human mast cell chemokine and cytokine production: involvement of G-protein activation

BACKGROUND

Activation of mast cells and the systemic release of histamine are common side effects of opiates such as codeine and morphine. In some individuals, codeine not only elicits a sizable early response due to mast cell degranulation, but can also lead to late cutaneous allergic inflammation possibly through the production of chemokines. However, individuals who exhibit a late phase reaction to codeine often do not react to its synthetic analog, meperidine. The goal of this study was to test whether codeine and meperidine induce secretion of inflammatory mediators in human mast cells.

METHODS

To characterize opiate activation of human mast cells, we stimulated cultured human (LAD2 cell line and CD34+-derived) mast cells with codeine and meperidine and measured degranulation and chemokine production.

RESULTS

Codeine, but not meperidine, activated human mast cell degranulation within 30 min in a dose-dependent manner. Degranulation was blocked by the phosphoinositol-3 kinase (PI3K) inhibitor, wortmannin, and pertussis toxin but not by Ro-31-8220, a PKC inhibitor or forskolin, a cyclic adenylyl cyclase activator. After 3 and 8 h of stimulation, codeine, but not meperidine, activated human mast cells to release monocyte chemoattractant protein-1 (CCL2), regulated on activation, normal T expressed and secreted (RANTES, CCL5) and interleukin-8 (CXCL 8) but not inducible protein-10 (CXCL10).

CONCLUSIONS

Codeine activates human mast cell degranulation and chemokine production by activating protein kinase A and PI3 kinase, possibly leading to NF-kappaB activation. Therefore, opiates may regulate late phase allergic inflammation by activating chemokine production by human mast cells.

TLR3 activation inhibits human mast cell attachment to fibronectin and vitronectin

Mast cells are involved in both the genesis of allergic inflammation and in host defense; and reside in tissues where their location and responsiveness is regulated in part by adhesion to extracellular matrix proteins (ECM). We have reported that human mast cells (huMC) express TLR1-7, and 9 and respond to toll-like receptors (TLR) ligands by releasing cytokines and leukotriene C4. To determine if TLR ligation could similarly affect mast cells via an influence on adhesion, we employed huMC; and as substrates, fibronectin (FN) and vitronectin (VN). huMC were thus treated with double-stranded RNA (dsRNA) and adhesion to ECM was quantified. FcvarepsilonRI dependent mast cell degranulation was assessed. Adhesion molecule expression and activation was measured by flow cytometry. Activation of huMC through TLR3 with increasing amounts of polyI:C inhibited mast cell adhesion in a dose-dependent manner. This decrease in adhesion was accompanied by a similar decrease in IgE-mediated mast cell degranulation. Activation of TLR3 on huMC resulted in a change in the conformation of CD29, the receptor for FN, to an inactive form. Thus, TLR3 activation decreases mast cell attachment to VN and FN through an active process and one, which would abrogate mast cell attachment dependent potentiation of IgE-mediated responses.

Apoptosis induced by a cytopathic hepatitis A virus is dependent on caspase activation following ribosomal RNA degradation but occurs in the absence of 2'-5' oligoadenylate synthetase

We have presented previously evidence that the cytopathogenic 18f strain of hepatitis A virus (HAV) induced degradation of ribosomal RNA (rRNA) in infected cells [Arch. Virol. 148 (2003) 1275–1300]. In contrast, the non-cytopathogenic parent virus HM175 clone 1 had no effect on rRNA integrity. We present here data showing that rRNA degradation is followed by apoptosis accompanied by characteristic DNA laddering in the cytoplasm of 18f infected cells. The DNA laddering coincided with the detection of caspase 3 and PARP-1 cleavage and was dependent upon activation of the caspase pathway, since treatment with Z-VAD-FMK, a pan-caspase inhibitor, inhibited both events. RNase L mRNA was present in both virus-infected and uninfected cells. Messenger RNA for the interferon inducible enzyme 2′–5′ oligoadenylate synthetase (2′–5′ OAS), which polymerizes ATP into 2′–5′ oligo adenylate (2–5A, the activator of RNase L) in the presence of double-stranded RNA, was not detected following virus infection. 2′–5′ OAS mRNA was induced by treatment of the cells with interferon-β (IFN-β). IFN-β mRNA was marginally induced following infection. However, phosphorylated STAT 1, a key regulator of interferon-stimulated gene transcription was not detected in virus infected cells. STAT 1 phosphorylation in response to IFN treatment was lower in virus-infected cells, compared to uninfected cells treated with interferon, suggesting that 18f virus infection interferes with interferon signaling. The results suggest that 18f infection causes the induction of a 2–5A independent RNase L like activity.

Use of reverse transcription and PCR to discriminate between infectious and non-infectious hepatitis A virus

Hepatitis A virus (HAV) is a major cause of infectious hepatitis worldwide. Detection of HAV in contaminated food or water is a priority research area in laboratories worldwide. Our laboratory has reported previously the development of reverse transcription-polymerase chain reaction (RT-PCR) based detection and typing methods for HAV in contaminated shellfish and produce. It is commonly held that RT-PCR can detect viral genome, but cannot distinguish between infectious and inactivated virus. Therefore, signals obtained after PCR should be considered as false positives unless it can be shown that the sample contains virus capable of infecting a suitable host cell line in culture. We present data to show that this general assumption is not valid. Evidence is provided that demonstrate that signals generated after RT-PCR amplification of viral genome correlated well with the presence of infectious virus in the sample. Viral samples inactivated by heat or UV treatment produced significantly lower signal strength that paralleled infectivity of the sample in cultured cells. The loss of signal strength is most likely the result of damage to the viral RNA that renders it unsuitable for RT-PCR. The correlation between PCR signal and infectivity was better following UV inactivation than heat treatment. The procedure may be adapted to other viruses and inactivating agents.

The cytopathic 18f strain of Hepatitis A virus induces RNA degradation in FrhK4 cells

The mechanism responsible for the induction of apoptosis by the rapidly replicating HM175/18f strain of Hepatitis A virus (HAV) was investigated. Full length HAV RNA and viral capsid protein VP1 were detected in 18f infected cells at earlier times post-infection than in HM175/clone 1 infected cells. Analysis of total cellular RNA from HM175/18f infected FrhK4 cells by denaturing agarose gel electrophoresis and Northern blot hybridization revealed extensive degradation of both the 28S and 18S ribosomal RNA (rRNA) molecules. Similar degradation was observed when these cells were infected with Human coxsackievirus B1, a fast replicating enterovirus. In contrast, the parental strain of 18f, HM175/clone 1 did not induce RNA degradation. Inhibition of RNA degradation correlated with inhibition of virus replication. The pattern of rRNA degradation resembled degradation of rRNAs by RNase L, an enzyme activated in interferon-treated cells following infection with certain viruses. Ribosomal RNA degradation was accompanied by the reduction in the levels of several cellular RNAs including those for beta-actin and glyceraldehyde-3-phosphate dehydrogenase, while the levels of c-myc and c-jun were higher. Interferon mRNAs could not be detected in either infected or mock-infected control cells, and STAT1, a key regulator of interferon action was not phosphorylated following virus infection. These results reveal a heretofore-undescribed pathway that involves the regulation of RNA degradation and apoptosis following HAV/18f replication in FrhK4 cells.

Mast cells express chloride channels of the ClC family

OBJECTIVE AND DESIGN

The expression of specific Cl- channels in mast cells (MC) is poorly understood. Because the largest and most ubiquitously expressed family of Cl- channels is the ClC, we studied MC mRNA and protein expression for members of the ClC family.

METHODS

Specific primers were designed to ClC-1 to -7 and reverse-transcriptase polymerase chain reaction (RT-PCR) was performed on RNA from highly purified rat peritoneal mast cells (PMC) and the rat cultured mast cell line (RCMC). Protein expression of ClC-2, -3 and -7 chloride channels in PMC and RCMC was studied using western blotting.

RESULTS

RT-PCR showed that RCMC expressed mRNA for the Cl- channels (ClC)-2, -3, -4, -5 and -7, while PMC expressed ClC-7. Using Western Blotting, we found protein expression of ClC-2 and ClC-7, but not ClC-3, in RCMC, whereas in PMC neither of these proteins could be detected.

CONCLUSION

These results indicate that MC express several members of the ClC family and that these Cl- channels might be important in MC functions.

Characteristics of nasal T/NK-cell lymphoma among Brazilians

Nasal T/NK-cell lymphomas are highly associated with Epstein-Barr virus (EBV). They are more frequent in Asia than in Western countries. In Central and South America there are few studies about nasal T/NK-cell lymphoma and they have shown a strong predominance of this phenotype in Native American descents, supporting the hypothesis of a racial predisposition for the disease. We studied the lymphomas involving midline facial region at a Brazilian institution. T/NK cell lymphomas (16/25) were more frequently found compared to B lymphomas (9 cases, all B large cell). T/NK cell lymphomas involved predominantly the nasal region. Histologically they showed angioinvasion and necrosis. All of them were positive for CD3 and CD56 and showed numerous tumor cells labeled by EBER-1. Although disease was localized in 61% at diagnosis, there was no tendency to cure. The racial distribution of patients with T/NK-cell phenotype was similar to that found in B-cell lymphomas. EBV was more frequently found in adenoids than in palatine tonsils. In inflammatory lesions of the nasal and palatal regions EBV was not found. In the present study the relative frequency of T/NK versus B cell sinonasal lymphomas was high and similar to that observed in other Latin American countries. However, there was not any racial association with T/NK-cell phenotype and the tumor showed an agressive behavior similar to that reported in Asia. The high frequency of EBV-positive lymphocytes in nasopharyngeal lymphoid tissue (adenoids) suggests that they could serve as a reservoir for the virus.

A polymerase chain reaction-based method for the detection of hepatitis A virus in produce and shellfish

Outbreaks of gastroenteritis that are suspected to be of viral origin are on the rise. Thus, there is a need for regulatory agencies entrusted with food safety to develop adequate techniques for the detection of viruses in foods. We have established a general procedure for the detection of hepatitis A virus (HAV) in shellfish that, with minor modifications, is also applicable to fresh produce such as cilantro. Total RNA was isolated from shellfish or cilantro, followed by isolation of poly(A)-containing RNA. Because HAV genomic RNA contains a poly(A) tail, the isolation of poly(A)-containing RNA also enriches HAV genomic RNA. Reverse transcription was used to convert the RNA to cDNA, and then amplification was carried out by polymerase chain reaction (PCR). Reamplification with internal primers was used to improve the quality and the quantity of amplified DNA, allowing for post-PCR analysis such as sequence identification of the viral strain. With this procedure, multiple samples could be analyzed in four working days by a single trained individual. The nominal sensitivity of detection of the procedure was 0.15 TCID50 (50% tissue culture infective dose) per 0.62 g of tissue with a test virus. The direct RNA isolation protocol avoided pitfalls associated with whole-virus purification procedures by replacing virus precipitation steps involving polyethylene glycol and Procipitate with phenol extraction. The method is straightforward and reliable. We successfully used this procedure to detect naturally occurring HAV in clams involved in a gastroenteritis outbreak, as well as in cilantro artificially contaminated with a test virus.

Expression and functional characterization of CFTR in mast cells

Mast cell activation requires Cl(-) flux, which maintains the driving force for entry of extracellular calcium and initiates release of mediators such as histamine. However, chloride channel expression in mast cells has been poorly understood. For the first time, reverse transcriptase-polymerase chain reaction shows that rat-cultured mast cells (RCMC) and peritoneal mast cells (PMC) contain mRNA for the cystic fibrosis transmembrane conductance regulator (CFTR), an important chloride channel. Immunostaining with an anti-CFTR antibody indicates expression of CFTR in PMC and RCMC. Mast cell CFTR is a functional Cl(-) channel because it is capable of mediating Cl(-) flux in response to elevated cAMP. An inhibitor of CFTR-dependent Cl(-) flux, diphenylamine-2-carboxylate down-regulates mast cell mediator release. These results show that rat mast cells express a functional CFTR, which might be important in mediator release.

Regulation of CD8 expression in mast cells by exogenous or endogenous nitric oxide

We recently reported a novel CD8 molecule on rat alveolar macrophages and peritoneal mast cells (PMC). However, little is known about the regulation of CD8 expression and function on these cells. We investigated the regulation of CD8 expression on PMC by NO, because NO can regulate inflammatory responses and also because anti-CD8 Ab stimulates inducible NO synthase and NO production by PMC and alveolar macrophages. Ligation of CD8alpha on PMC with Ab (OX8) induced CD8alpha mRNA expression after 3-6 h, and flow cytometry demonstrated that OX8 treatment increased CD8alpha protein expression compared with PMC treated with isotype control IgG1. To test whether NO mediates the up-regulation of CD8alpha, we used the NO donor S-nitrosoglutathione (500 microM) and NO synthase inhibitors (N(G)-monomethyl-L-arginine and N(G)-nitro-L-arginine methyl ester; 100 microM). S-nitrosoglutathione up-regulated both mRNA and protein expression of CD8alpha in PMC compared with that in sham-treated cells, while NO synthase inhibitors down-regulated OX8 Ab-induced CD8alpha expression. To investigate how NO regulates CD8 expression on PMC, we examined the cGMP-dependent pathway using 8-bromo-cGMP (2 mM) and the guanylate cyclase inhibitor, 1H-oxadiazoloquinoxalin-1-one (20 microM). 8-Bromo-cGMP up-regulated CD8 expression, whereas 1H-oxadiazoloquinoxalin-1-one down-regulated its expression. Thus, ligation of CD8 up-regulates CD8 expression on PMC, a response mediated at least in part by NO through a cGMP-dependent pathway. The significance of this up-regulation of CD8alpha on mast cells (MC) is unclear, but since ligation of CD8 on MC with OX8 Ab can alter gene expression and mediator secretion, up-regulation of CD8 may enhance the MC response to natural ligation of this novel form of CD8.

Mast cells and nitric oxide: control of production, mechanisms of response

Mast cells are involved in numerous activities ranging from control of the vasculature, to tissue injury and repair, allergic inflammation and host defences. They synthesize and secrete a variety of mediators, activating and modulating the functions of nearby cells and initiating complex physiological changes. Interestingly, NO produced by mast cells and/or other cells in the microenvironment appears to regulate these diverse roles. This review outlines some of the pathways central to the production of NO by mast cells and identifies many of the tightly controlled regulatory mechanisms involved. Several cofactors and regulatory elements are involved in NO production, and these act at transcriptional and post-translational sites. Their involvement in NO production will be outlined and the possibility that these pathways are critically important in mast cell functions will be discussed. The effects of NO on mast cell functions such as adhesion, activation and mediator secretion will be examined with a focus on molecular mechanisms by which NO modifies intracellular signalling pathways dependent or independent of cGMP and soluble guanylate cyclase. The possibility that NO regulates mast cell function through effects on selected ion channels will be discussed. Metabolic products of NO including peroxynitrite and other reactive species may be the critical elements that affect the actions of NO on mast cell functions. Further understanding of the actions of NO on mast cell activities may uncover novel strategies to modulate inflammatory conditions.

A growth and latency compromised herpes simplex virus type 2 mutant (ICP10DeltaPK) has prophylactic and therapeutic protective activity in guinea pigs

A growth compromised herpes simplex virus type 2 (HSV-2) mutant which is deleted in the PK domain of the large subunit of ribonucleotide reductase (ICP10DeltaPK) protects from fatal HSV-2 challenge in the mouse model (Aurelian L, Kokuba H, Smith CC. Vaccine potential of a Herpes Simplex Virus type 2 mutant deleted in the PK domain of the large subunit of ribonucleotide reductase (ICP10). Vaccine 1999;17:1951-1963). Here we report the results of our studies with ICP10DeltaPK in the guinea pig model of recurrent HSV-2 disease. ICP10DeltaPK was also compromised for growth and disease causation in this model. It was not isolated from latently infected ganglia by explant co-cultivation. The proportions of latently infected ganglia were significantly lower for ICP10DeltaPK than HSV-2 [3/25 (12%) and 7/10 (70%), respectively]. Similar results were obtained for the levels of viral DNA (8 x 10(3) and 2 x 10(5) molecules/ganglion for ICP10DeltaPK and HSV-2, respectively]. ICP10DeltaPK immunization caused a significant (P< or = 0.001) decrease in the proportion of animals with primary [1/14 (6%) and 16/16 (100%) for ICP10DeltaPK and PBS, respectively) and recurrent [1/14 (6%) and 11/14 (79%) for ICP10DeltaPK and PBS, respectively) HSV-2 skin lesions. It also protected from genital HSV-2 disease [1/10 and 10/10 for ICP10DeltaPK and PBS, respectively] and decreased the severity of the lesions in both models. Quantitative PCR (Q-PCR) with primers that distinguish between HSV-2 and ICP10DeltaPK indicated that immunization reduced the proportion of ganglia positive for HSV-2 DNA [8/25 (32%) and 7/10 (70%) for ICP10DeltaPK and PBS, respectively) and its levels [3 x 10(3) and 2 x 10(5) molecules/ganglion for ICP10DeltaPK and PBS, respectively]. The proportion of HSV-2 infected animals with recurrent disease was also significantly (P < or = 0.001) decreased by immunization with ICP10DeltaPK [1/15 (7%) and 11/14 (79%) with recurrent disease for ICP10DeltaPK and PBS, respectively], suggesting that ICP10DeltaPK has prophylactic and therapeutic activity in the guinea pig.

A novel gene expressed in human keratinocytes with long-term in vitro growth potential is required for cell growth

The herpes simplex virus large subunit of ribonucleotide reductase differs from its counterparts in eukaryotic and prokaryotic cells and in other viruses in that it contains a unique domain that codes for a distinct serine-threonine protein kinase that activates the Ras/MEK/MAPK mitogenic pathway and is required for virus growth. Previous studies suggested that ribonucleotide reductase protein kinase was co-opted from a cellular gene. Cellular genes similar to ribonucleotide reductase protein kinase were not cloned, however, and their function is unknown. Here we report that a novel gene (H11) that codes for a protein similar to herpes simplex virus 2 ribonucleotide reductase protein kinase, is expressed in skin tissues, cultured keratinocytes, and the keratinocyte cell line A431. The protein is phosphorylated and it associates with the plasma membrane. H11 is expressed in keratinocytes with long-term in vitro growth potential and is coexpressed with high levels of adhesion molecules involved in signal transduction, such as beta1 integrin. Antisense oligonucleotides that inhibit H11 expression inhibit DNA synthesis and keratinocyte proliferation, suggesting that H11 expression is required for cell growth.

Modified adenovirus penton base protein (UTARVE) as a non-replicating vector for delivery of antisense oligonucleotides with antiviral and/or antineoplastic activity

Antisense oligonucleotides that selectively inhibit gene expression are a genetic approach for disease treatment and prevention. However, their use as therapeutic agents is complicated by their low rate of transport across cellular membranes and their sequestration within endocytic-like vesicles. We report that the adenovirus type-2 penton base protein modified to include the fusogenic peptide of the influenza virus hemagglutinin protein is a non-replicating vector (designated UTARVE) that improves delivery of antisense oligonucleotides. Approximately 10-18% of the input vector was internalized by A549 and HeLa cells as determined by immunoblotting. It was cleared by proteolysis within 48 h. The vector had endosome disruptive potential as evidenced by erythrocyte lysis activity at low pH and a primarily diffuse cytoplasmic distribution in treated cells. Despite concentration and time-dependent cell detachment, UTARVE was not cytotoxic in the dye release assay. We used R1T1, an antisense oligonucleotide that inhibits expression of the multifunctional herpes simplex virus type-2 (HSV-2) R1 protein, HSV-2 growth and the proliferation of R1 PK transformed cells to examine vector-mediated delivery. Conjugated FITC-labeled R1T1 was rapidly (15-30 min) internalized by all cells treated at low (80 nM) concentration and the oligomer was intracellularly dissociated from the vector. This compares to 65-83% of cells internalizing the unconjugated R1T1 when treated for 24 h. In antiviral assays, the IC50 and time required to inhibit HSV-2 growth were significantly lower for the conjugated (2 nM; 30 min) as compared to unconjugated (100 nM; 24 h) R1T1. The data indicate that the bioavailability and biological activity of R1T1 were significantly increased by its delivery with UTARVE.