Protein Compartments Modulate Fibrillar Self-Assembly

A notable feature of complex cellular environments is protein-rich compartments that are formed via liquid-liquid phase separation. Recent studies have shown that these biomolecular condensates can play both promoting and inhibitory roles in fibrillar protein self-assembly, a process that is linked to Alzheimer's, Parkinson's, Huntington's, and various prion diseases. Yet, the exact regulatory role of these condensates in protein aggregation remains unknown. By employing microfluidics to create artificial protein compartments, the self-assembly behavior of the fibrillar protein lysozyme within them can be characterized. It is observed that the volumetric parameters of protein-rich compartments can change the kinetics of protein self-assembly. Depending on the change in compartment parameters, the lysozyme fibrillation process either accelerated or decelerated. Furthermore, the results confirm that the volumetric parameters govern not only the nucleation and growth phases of the fibrillar aggregates but also affect the crosstalk between the protein-rich and protein-poor phases. The appearance of phase-separated compartments in the vicinity of natively folded protein complexes triggers their abrupt percolation into the compartments' core and further accelerates protein aggregation. Overall, the results of the study shed more light on the complex behavior and functions of protein-rich phases and, importantly, on their interaction with the surrounding environment.

Transport-Limited Growth of Coccolith Crystals

Biogenic crystals present a variety of complex morphologies that form with exquisite fidelity. In the case of the intricate morphologies of coccoliths, calcite crystals produced by marine algae, only a single set of crystallographic facets is utilized. It is unclear which growth process can merge this simple crystallographic habit with the species-specific architectures. Here, a suite of state-of-the-art electron microscopies is used to follow both the growth trajectories of the crystals ex situ, and the cellular environment in situ, in the species Emiliania huxleyi. It is shown that crystal growth alternates between a space filling and a skeletonized growth mode, where the crystals elongate via their stable crystallographic facets, but the final morphology is a manifestation of growth arrest. This process is reminiscent of the balance between reaction-limited and transport-limited growth regimes underlying snowflake formation. It is suggested that localized ion transport regulates the kinetic instabilities that are required for transport-limited growth, leading to reproducible morphologies.

Polymer-Rich Dense Phase Can Concentrate Metastable Silica Precursors and Regulate Their Mineralization

Multistep mineralization processes are pivotal in the fabrication of functional materials and are often characterized by far from equilibrium conditions and high supersaturation. Interestingly, such 'nonclassical' mineralization pathways are widespread in biological systems, even though concentrating molecules well beyond their saturation level is incompatible with cellular homeostasis. Here, we show how polymer phase separation can facilitate bioinspired silica formation by passively concentrating the inorganic building blocks within the polymer dense phase. The high affinity of the dense phase to mobile silica precursors generates a diffusive flux against the concentration gradient, similar to dynamic equilibrium, and the resulting high supersaturation leads to precipitation of insoluble silica. Manipulating the chemistry of the dense phase allows to control the delicate interplay between polymer chemistry and silica precipitation. These results connect two phase transition phenomena, mineralization and coacervation, and offer a framework to achieve better control of mineral formation.

The disulfide catalyst QSOX1 maintains the colon mucosal barrier by regulating Golgi glycosyltransferases

Mucus is made of enormous mucin glycoproteins that polymerize by disulfide crosslinking in the Golgi apparatus. QSOX1 is a catalyst of disulfide bond formation localized to the Golgi. Both QSOX1 and mucins are highly expressed in goblet cells of mucosal tissues, leading to the hypothesis that QSOX1 catalyzes disulfide-mediated mucin polymerization. We found that knockout mice lacking QSOX1 had impaired mucus barrier function due to production of defective mucus. However, an investigation on the molecular level revealed normal disulfide-mediated polymerization of mucins and related glycoproteins. Instead, we detected a drastic decrease in sialic acid in the gut mucus glycome of the QSOX1 knockout mice, leading to the discovery that QSOX1 forms regulatory disulfides in Golgi glycosyltransferases. Sialylation defects in the colon are known to cause colitis in humans. Here we show that QSOX1 redox control of sialylation is essential for maintaining mucosal function.

Plate-like Guanine Biocrystals Form via Templated Nucleation of Crystal Leaflets on Preassembled Scaffolds

Controlling the morphology of crystalline materials is challenging, as crystals have a strong tendency toward thermodynamically stable structures. Yet, organisms form crystals with distinct morphologies, such as the plate-like guanine crystals produced by many terrestrial and aquatic species for light manipulation. Regulation of crystal morphogenesis was hypothesized to entail physical growth restriction by the surrounding membrane, combined with fine-tuned interactions between organic molecules and the growing crystal. Using cryo-electron tomography of developing zebrafish larvae, we found that guanine crystals form via templated nucleation of thin leaflets on preassembled scaffolds made of 20-nm-thick amyloid fibers. These leaflets then merge and coalesce into a single plate-like crystal. Our findings shed light on the biological regulation of crystal morphogenesis, which determines their optical properties.

Electron microscopy of cellular ultrastructure in three dimensions

Electron microscopy in three dimensions (3D) of cells and tissues can be essential for understanding the ultrastructural aspects of biological processes. The quest for 3D information reveals challenges at many stages of the workflow, from sample preparation, to imaging, data analysis and segmentation. Here, we outline several available methods, including volume SEM imaging, cryo-TEM and cryo-STEM tomography, each one occupying a different domain in the basic tradeoff between field-of-view and resolution. We discuss the considerations for choosing a suitable method depending on research needs and highlight recent developments that are essential for making 3D volume imaging of cells and tissues a standard tool for cellular and structural biologists.

Polymorphism, Structure, and Nucleation of Cholesterol·H2O at Aqueous Interfaces and in Pathological Media: Revisited from a Computational Perspective

We revisit the important issues of polymorphism, structure, and nucleation of cholesterol·H₂O using first-principles calculations based on dispersion-augmented density functional theory. For the lesser known monoclinic polymorph, we obtain a fully extended H-bonded network in a structure akin to that of hexagonal ice. We show that the energy of the monoclinic and triclinic polymorphs is similar, strongly suggesting that kinetic and environmental effects play a significant role in determining polymorph nucleation. Furthermore, we find evidence in support of various O–H···O bonding motifs in both polymorphs that may result in hydroxyl disorder. We have been able to explain, via computation, why a single cholesterol bilayer in hydrated membranes always crystallizes in the monoclinic polymorph. We rationalize what we believe is a single-crystal to single-crystal transformation of the monoclinic form on increased interlayer growth beyond that of a single cholesterol bilayer, interleaved by a water bilayer. We show that the ice-like structure is also relevant to the related cholestanol·2H₂O and stigmasterol·H₂O crystals. The structure of stigmasterol hydrate both as a trilayer film at the air–water interface and as a macroscopic crystal further assists us in understanding the polymorphic and thermal behavior of cholesterol·H₂O. Finally, we posit a possible role for one of the sterol esters in the crystallization of cholesterol·H₂O in pathological environments, based on a composite of a crystalline bilayer of cholesteryl palmitate bound epitaxially as a nucleating agent to the monoclinic cholesterol·H₂O form.

Characterization of the growth plate-bone interphase region using cryo-FIB SEM 3D volume imaging

The interphase region at the base of the growth plate includes blood vessels, cells and mineralized tissues. In this region, cartilage is mineralized and replaced with bone. Blood vessel extremities permeate this space providing nutrients, oxygen and signaling factors. All these different components form a complex intertwined 3D structure. Here we use cryo-FIB SEM to elaborate this 3D structure without removing the water. As it is challenging to image mineralized and unmineralized tissues in a hydrated state, we provide technical details of the parameters used. We obtained two FIB SEM image stacks that show that the blood vessels are in intimate contact not only with cells, but in some locations also with mineralized tissues. There are abundant red blood cells at the extremities of the vessels. We also documented large multinucleated cells in contact with mineralized cartilage and possibly also with bone. We observed membrane bound mineralized particles in these cells, as well as in blood serum, but not in the hypertrophic chondrocytes. We confirm that there is an open pathway from the blood vessel extremities to the mineralizing cartilage. Based on the sparsity of the mineralized particles, we conclude that mainly ions in solution are used for mineralizing cartilage and bone, but these are augmented by the supply of mineralized particles.

Genetic basis of stony coral biomineralization: History, trends and future prospects

Despite their simple body plan, stony corals (order Scleractinia, phylum Cnidaria) can produce massive and complex exoskeletal structures in shallow, tropical and subtropical regions of Earth's oceans. The species-specific macromorphologies of their aragonite skeletons suggest a highly coordinated biomineralization process that is rooted in their genomes, and which has persisted across major climatic shifts over the past 400 + million years. The mechanisms by which stony corals produce their skeletons has been the subject of interest for at least the last 160 years, and the pace of understanding the process has increased dramatically in the past decade since the sequencing of the first coral genome in 2011. In this review, we detail what is known to date about the genetic basis of the stony coral biomineralization process, with a focus on advances in the last several years as well as ways that physical and chemical tools can be combined with genetics, and then propose next steps forward for the coming decade.

Fluorescent Silica Nanoparticles to Label Metastatic Tumor Cells in Mineralized Bone Microenvironments

During breast cancer bone metastasis, tumor cells interact with bone microenvironment components including inorganic minerals. Bone mineralization is a dynamic process and varies spatiotemporally as a function of cancer-promoting conditions such as age and diet. The functional relationship between skeletal dissemination of tumor cells and bone mineralization, however, is unclear. Standard histological analysis of bone metastasis frequently relies on prior demineralization of bone, while methods that maintain mineral are often harsh and damage fluorophores commonly used to label tumor cells. Here, fluorescent silica nanoparticles (SNPs) are introduced as a robust and versatile labeling strategy to analyze tumor cells within mineralized bone. SNP uptake and labeling efficiency of MDA-MB-231 breast cancer cells is characterized with cryo-scanning electron microscopy and different tissue processing methods. Using a 3D in vitro model of marrow-containing, mineralized bone as well as an in vivo model of bone metastasis, SNPs are demonstrated to allow visualization of labeled tumor cells in mineralized bone using various imaging modalities including widefield, confocal, and light sheet microscopy. This work suggests that SNPs are valuable tools to analyze tumor cells within mineralized bone using a broad range of bone processing and imaging techniques with the potential to increase the understanding of bone metastasis.

Cellular pathways of calcium transport and concentration toward mineral formation in sea urchin larvae

Sea urchin larvae have an endoskeleton consisting of two calcitic spicules. The primary mesenchyme cells (PMCs) are the cells that are responsible for spicule formation. PMCs endocytose sea water from the larval internal body cavity into a network of vacuoles and vesicles, where calcium ions are concentrated until they precipitate in the form of amorphous calcium carbonate (ACC). The mineral is subsequently transferred to the syncytium, where the spicule forms. Using cryo-soft X-ray microscopy we imaged intracellular calcium-containing particles in the PMCs and acquired Ca-L2,3 X-ray absorption near-edge spectra of these Ca-rich particles. Using the prepeak/main peak (L2'/ L2) intensity ratio, which reflects the atomic order in the first Ca coordination shell, we determined the state of the calcium ions in each particle. The concentration of Ca in each of the particles was also determined by the integrated area in the main Ca absorption peak. We observed about 700 Ca-rich particles with order parameters, L2'/ L2, ranging from solution to hydrated and anhydrous ACC, and with concentrations ranging between 1 and 15 M. We conclude that in each cell the calcium ions exist in a continuum of states. This implies that most, but not all, water is expelled from the particles. This cellular process of calcium concentration may represent a widespread pathway in mineralizing organisms.

The Effect of the Phospholipid Bilayer Environment on Cholesterol Crystal Polymorphism

Invited for this month's cover are the group of Prof. Lia Addadi at the Weizmann Institute of Science, Israel and collaborators at the Università Degli Studi di Milano, Italy, and the ALBA Synchrotron Light Source, Spain. The front cover shows how cholesterol crystals form in macrophage cells and in lipid bilayers of different compositions. Cholesterol monohydrate stable triclinic crystals form in vitro as rhomb-shaped plates, whereas the monoclinic crystals fold into tubular or helical shapes. Read the full text of the article at 10.1002/cplu.201800632.

Mineralization pathways in the active murine epiphyseal growth plate

Endochondral ossification in the growth plate of long bones involves cartilage mineralization, bone formation and the budding vasculature. Many of these processes take place in a complex and dynamic zone, the provisional ossification zone, of the growth plate. Here we investigate aspects of mineralization in 2D and 3D in the provisional ossification zone at different length scales using samples preserved under cryogenic or fully hydrated conditions. We use confocal light microscopy, cryo-SEM and micro-CT in the phase contrast mode. We show in 9 week old BALB/c mice the presence of vesicles containing mineral particles in the blood serum, as well as mineral particles without membranes integrated with the blood vessel walls. We also observe labeled mineral particles within cells associated with bone formation, but not in the hypertrophic cartilage cells that are involved with cartilage mineralization. High resolution micro-CT images of fresh hydrated tibiae, show that there are open continuous pathways between the blood vessel extremities and the hypertrophic chondrocyte zone. As the blood vessel extremities, the mineralizing cartilage and the forming bone are all closely associated within this narrow zone, we raise the possibility that in addition to ion transport, mineral necessary for both cartilage and bone formation is also transported through the vasculature.

Macrophages Shed Excess Cholesterol in Unique Extracellular Structures Containing Cholesterol Microdomains

Supplemental Digital Content is available in the text.

Objective—

Cells use various mechanisms to maintain cellular cholesterol homeostasis including efflux of cholesterol from the cellular plasma membrane to cholesterol acceptors such as HDLs (high-density lipoproteins). Little is known about the transfer of cholesterol from cells into the extracellular matrix. Using a unique monoclonal antibody that detects ordered cholesterol arrays (ie, cholesterol micro[or nano]-domains), we previously identified that particles containing these cholesterol domains accumulate in the extracellular matrix during cholesterol enrichment of human monocyte-derived macrophages and are found in atherosclerotic lesions. In this study, we further investigate these deposited particles containing cholesterol microdomains and discover their unexpected morphology.

Approach and Results—

Although appearing spherical at the resolution of the conventional fluorescence microscope, super-resolution immunofluorescence and atomic force microscopy of in situ cholesterol microdomains, and immunoelectron microscopy of isolated cholesterol microdomains revealed that the microdomains are not vesicles or 3-dimensional crystals but rather appear as branching irregularly shaped deposits of varying size. These cholesterol microdomain-containing deposits are shed from the plasma membrane into the extracellular matrix.

Conclusions—

To date, research on cellular excretion of excess cholesterol has demonstrated cellular cholesterol efflux in the form of membranous vesicles and discoidal HDL particles released into the fluid-phase medium. Shedding of plasma membrane cholesterol microdomains provides an additional mechanism for cells such as macrophages to maintain plasma membrane cholesterol homeostasis. Furthermore, recognition that macrophages shed cholesterol microdomains into the extracellular matrix is important to our understanding of extracellular buildup of cholesterol in atherosclerosis.

Development of Correlative Cryo-soft X-ray Tomography and Stochastic Reconstruction Microscopy. A Study of Cholesterol Crystal Early Formation in Cells

We have developed a high resolution correlative method involving cryo-soft X-ray tomography (cryo-SXT) and stochastic optical reconstruction microscopy (STORM), which provides information in three dimensions on large cellular volumes at 70 nm resolution. Cryo-SXT morphologically identified and localized aggregations of carbon-rich materials. STORM identified specific markers on the desired epitopes, enabling colocalization between the identified objects, in this case cholesterol crystals, and the cellular environment. The samples were studied under ambient and cryogenic conditions without dehydration or heavy metal staining. The early events of cholesterol crystal development were investigated in relation to atherosclerosis, using as model macrophage cell cultures enriched with LDL particles. Atherosclerotic plaques build up in arteries in a slow process involving cholesterol crystal accumulation. Cholesterol crystal deposition is a crucial stage in the pathological cascade. Our results show that cholesterol crystals can be identified and imaged at a very early stage on the cell plasma membrane and in intracellular locations. This technique can in principle be applied to other biological samples where specific molecular identification is required in conjunction with high resolution 3D-imaging.

ABCA1 contributes to macrophage deposition of extracellular cholesterol

We previously reported that cholesterol-enriched macrophages excrete cholesterol into the extracellular matrix. A monoclonal antibody that detects cholesterol microdomains labels the deposited extracellular particles. Macro-phage deposition of extracellular cholesterol depends, in part, on ABCG1, and this cholesterol can be mobilized by HDL components of the reverse cholesterol transport process. The objective of the current study was to determine whether ABCA1 also contributes to macrophage deposition of extracellular cholesterol. ABCA1 functioned in extracellular cholesterol deposition. The liver X receptor agonist, TO901317 (TO9), an ABCA1-inducing factor, restored cholesterol deposition that was absent in cholesterol-enriched ABCG1(-/-) mouse macrophages. In addition, the ABCA1 inhibitor, probucol, blocked the increment in cholesterol deposited by TO9-treated wild-type macrophages, and completely inhibited deposition from TO9-treated ABCG1(-/-) macrophages. Lastly, ABCA1(-/-) macrophages deposited much less extracellular cholesterol than wild-type macrophages. These findings demonstrate a novel function of ABCA1 in contributing to macrophage export of cholesterol into the extracellular matrix.

Abstract 534: Abca1 Mediates Macrophage Deposition of Cholesterol Into the Extracellular Matrix

ABCG1 and ABCA1 both function in reverse cholesterol transport. We previously reported that cholesterol-enriched macrophages deposit cholesterol into the extracellular space and this process depends in part on ABCG1. The extracellular cholesterol deposits can be mobilized by HDL. The objective of the current study was to determine whether ABCA1 also contributes to macrophage deposition of extracellular cholesterol. A monoclonal antibody that detects cholesterol microdomains, and not isolated cholesterol molecules, labels these extracellular deposits. First, to confirm the specificity of the cholesterol labeling, we treated cholesterol-enriched macrophages cultures with cholesterol oxidase and found that antibody labeling of deposits was eliminated. Many biochemical studies assume that cholesterol oxidase susceptible cholesterol indicates this cholesterol is within the plasma membrane. However, as we show here, the extracellular pool of cholesterol also contributes to cholesterol oxidase susceptible cholesterol. Second, concerning ABCA1 function in cholesterol deposition, we observed that the LXR agonist, TO901317, an ABCA1-inducing agent, restored cholesterol deposition that was absent in ABCG1-/- mouse macrophages. In addition, probucol, an agent that inhibits ABCA1 function, partially inhibited cholesterol deposited by wild-type mouse macrophages, and completely inhibited deposition from TO901317-treated ABCG1-/- mouse macrophages. These results suggest that ABCA1 contributes to macrophage cholesterol deposition. We confirmed this conclusion by testing cholesterol deposition in ABCA1-/- mouse macrophages. Extracellular cholesterol deposition by these macrophages was substantially reduced compared with wild-type mouse macrophages. Thus, our findings demonstrate a novel function of ABCA1 in contributing to macrophage export of cholesterol into the extracellular space where this cholesterol can be stored until mobilized by HDL.

Vaccination against influenza in rheumatoid arthritis: the effect of disease modifying drugs, including TNF alpha blockers

OBJECTIVE

To assess the efficacy and safety of vaccination against influenza virus in patients with rheumatoid arthritis, with special emphasis on the effect of disease modifying antirheumatic drugs (DMARDs), including tumour necrosis factor alpha (TNFalpha) blockers.

METHODS

82 rheumatoid patients and 30 healthy controls were vaccinated with a split-virion inactivated vaccine containing 15 mug haemagglutinin (HA) per dose of each of B/Hong Kong/330/2001 (HK), A/Panama/2007/99 (PAN), and A/New Caledonian/20/99 (NC). Disease activity was assessed by tender and swollen joint count, morning stiffness, evaluation of pain, Health Assessment Questionnaire, ESR, and C reactive protein on the day of vaccination and six weeks later. Haemagglutination inhibiting (HI) antibodies were tested by a standard WHO procedure. Response was defined as a fourfold or more rise in HI antibodies six weeks after vaccination, or seroconversion in patients with a non-protective baseline level of antibodies (<1/40). Geometric mean titres (GMT) were calculated to assess the immunity of the whole group.

RESULTS

Six weeks after vaccination, a significant increase in GMT for each antigen was observed in both groups, this being higher in the healthy group for HK (p=0.004). The percentage of responders was lower in rheumatoid patients than healthy controls (significant for HK). The percentage of responders was not affected by prednisone or any DMARD, including methotrexate, infliximab, and etanercept. Indices of disease activity remained unchanged.

CONCLUSIONS

Influenza virus vaccine generated a good humoral response in rheumatoid patients, although lower than in healthy controls. The response was not affected by the use of prednisone or DMARDs.

Emergence of influenza A H1N2 reassortant viruses in the human population during 2001

Influenza A H1N2 viruses, which emerged during 2001, are genetic reassortants between H1N1 and H3N2 subtype viruses which have cocirculated in the human population since 1977. They possess a H1 hemagglutinin antigenically and genetically similar to contemporary A/New Caledonia/20/99 (H1N1)-like viruses and seven genes closely related to those of recent A/Moscow/10/99 (H3N2)-like viruses. The viruses have spread to many regions of the world and have predominated over H1N1 viruses in several countries. Since half of the amino acid changes which accumulated in the HAs of H1N1 viruses since 1995 are in residues implicated in receptor binding, functional changes in the H1 HA may have facilitated its replacement of the H3 HA and may contribute to the future epidemiologic significance of these H1N2 viruses.

Influenza surveillance during winter 1997-1998 in Israel

BACKGROUND

Each winter influenza activity is a major cause of morbidity and mortality both in Israel and worldwide.

OBJECTIVES

To identify the influenza viruses active in Israel during the winter season and to assess the extent of influenza morbidity.

METHODS

Information was collected on a population of 18,684 individuals enrolled in two community clinics in central Israel. It included the total number of visits for acute respiratory infection--including influenza and influenza-like illness (ARI/flu-like)--during a 20 week surveillance period (23 November 1997 to 27 March 1998) and the percent of influenza virus isolates in nasopharyngeal specimens from a sample of patients with ARI/flu-like collected on a weekly basis during the same period.

RESULTS

A total of 5,947 visits for ARI/flu-like were recorded among 18,684 enrolled patients in two community clinics (18.1%). The progressive increase in the number of visits for ARI/flu-like reached a peak on week 2/98 with 597 visits and a rate of 31.95 visits per 1,000 population. After this, a decrease to the initial values was evident by week 12/98. Most affected patients were in the age groups 5-14 and 65 years and over, with a rate of 733.5 and 605.3 visits per 1,000 population, respectively. Influenza virus was isolated from 92 of the 426 nasopharyngeal specimens (21.6%). The most commonly detected strain was A/Sydney/5/97 (H3N2) like (77.2%). The peak rate of isolates was recorded at the beginning of January (01/98).

CONCLUSIONS

A/Sydney/5/97 (H3N2) like-strain was the dominant influenza virus. Its presence did not prevent the simultaneous activity of influenza A/H1N1 virus. The dynamic of the clinical disease as expressed by the weekly visit rate for ARI/flu-like was similar to the temporal pattern of the virological findings. The extent of morbidity suggests moderate epidemic activity.

Molecular epidemiology of adenovirus type 7 in Israel: identification of two new genome types, Ad7k and Ad7d2

The molecular epidemiology of Adenovirus type 7 in Israel was investigated. Fifty-seven adenovirus isolates identified as serotypes 7 or 7a which were recovered from patients in Israel between 1968 and 1995 were analyzed by restriction enzymes digestion using BamHI for primary discrimination and identification of genome types and by six additional enzymes: BstEII, HpaI, BglI, BglII, BclI, and XbaI for confirmation and determination of genomic subtypes. Four digestion patterns were identified with BamHI; one of them was new. Using BstEII, two patterns were obtained, one of them new. Digestion with the other five enzymes yielded known patterns. The analysis revealed four different genomic types and subtypes, which circulated in Israel in different years: subtype 7a1; type 7b, a type with a new BamHI pattern which was designated type 7K, and a subtype with a new BstEII pattern which differed from type 7d by one restriction site and was designated type 7d2. Twenty-two isolates from 1968 through 1975 and from 1984 were Ad7a1. Three isolates from 1973-1974 were Ad7b. Five isolates from 1968 through 1973 were Ad7K and 27 isolates from 1992 through 1995 were Ad7d2. This demonstrates the temporal change in the circulating genome types with up to three genome types cocirculating in 1 year (1973). The two new types, Ad7k and Ad7d2 could have evolved in Israel or could have been imported by travellers and immigrants from neighboring or distant countries.

Influenza vaccine efficacy in young, healthy adults

Findings concerning influenza vaccine efficacy in young, healthy adults are inconsistent. A high incidence of influenza in the winter of 1995 provided an opportunity to study the efficacy of influenza vaccine among young, healthy military personnel. Influenza activity was confirmed by isolation of influenza A and B viruses from nasopharyngeal swab specimens from hospitalized soldiers. Self-administered questionnaires concerning vaccination status and disease symptoms were used in two study groups: recruits and veteran soldiers serving in different camps. Six hundred eighty-four individuals had received influenza vaccine and 652 had not. Vaccine efficacy was found to be 38.1% (P = .002) for preventing febrile illness with or without symptoms and slightly higher (41.6%; P < .001) for preventing fever together with upper respiratory tract symptoms. The current influenza vaccine significantly reduced febrile illness among healthy military personnel.

Inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry extract (Sambucus nigra L.) during an outbreak of influenza B Panama

A standardized elderberry extract, Sambucol (SAM), reduced hemagglutination and inhibited replication of human influenza viruses type A/Shangdong 9/93 (H3N2), A/Beijing 32/92 (H3N2), A/Texas 36/91 (H1N1), A/Singapore 6/86 (H1N1), type B/Panama 45/90, B/Yamagata 16/88, B/Ann Arbor 1/86, and of animal strains from Northern European swine and turkeys, A/Sw/Ger 2/81, A/Tur/Ger 3/91, and A/Sw/Ger 8533/91 in Madin-Darby canine kidney cells. A placebo-controlled, double blind study was carried out on a group of individuals living in an agricultural community (kibbutz) during an outbreak of influenza B/Panama in 1993. Fever, feeling of improvement, and complete cure were recorded during 6 days. Sera obtained in the acute and convalescent phases were tested for the presence of antibodies to influenza A, B, respiratory syncytial, and adenoviruses. Convalescent phase serologies showed higher mean and mean geometric hemagglutination inhibition (HI) titers to influenza B in the group treated with SAM than in the control group. A significant improvement of the symptoms, including fever, was seen in 93.3% of the cases in the SAM-treated group within 2 days, whereas in the control group 91.7% of the patients showed an improvement within 6 days (p < 0.001). A complete cure was achieved within 2 to 3 days in nearly 90% of the SAM-treated group and within at least 6 days in the placebo group (p < 0.001). No satisfactory medication to cure influenza type A and B is available. Considering the efficacy of the extract in vitro on all strains of influenza virus tested, the clinical results, its low cost, and absence of side-effects, this preparation could offer a possibility for safe treatment for influenza A and B.

Identification of a new strain of fastidious enterovirus 70 as the causative agent of an outbreak of hemorrhagic conjunctivitis

A 1994 outbreak of acute hemorrhagic conjunctivitis in Israel was caused by an enterovirus 70 strain that was distinct from previously reported strains. Characterization was by electron microscopy (eye washes), reverse transcription-PCR (RT-PCR; eyewash, specimens, eye swabs, and tears), and sequence analysis of RT-PCR-amplified fragments from the 5' noncoding region and VP1.

Detection of adeno-associated virus type 2 sequences in the human genital tract

Adeno-associated virus (AAV) is a defective parvovirus with unknown pathogenicity. It requires helper functions for its normal replication in human tissue and therefore is not readily isolated from clinical specimens. We have used the PCR method to examine the following clinical samples for the presence of AAV sequences: (i) 15 nasopharyngeal aspirates from symptomatic patients, (ii) 7 swab or fluid specimens from vesicles of patients suspected of having varicella-zoster virus infections, (iii) 21 human papilloma virus-positive genital biopsy specimens, (iv) 61 genital swab specimens from women suspected of having herpes simplex virus (HSV) infection examined either directly or following propagation in tissue culture, (v) 62 samples of first-trimester aborted material, including 38 samples from spontaneous abortions and 24 samples from induced abortions, (vi) 11 samples of chorionic villi taken from women undergoing genetic prenatal diagnosis, and (vii) three lots of cultured human embryonic cells. AAV sequences were detected only in samples taken from the genital tracts of women suspected of having HSV infection and not in any of the other types of samples. Samples from 11 patients were positive for AAV: for 4 patients the original swab sample was positive, for 4 patients the cultured swab sample was positive, and for 3 patients both the original swab samples and the cultures were positive. Five of the 11 patients were infected with HSV. Our study demonstrates the presence of AAV in the female genital tract. However, in contrast to a previous report (E. Tobiasch, M. Rabreau, K. Geletneky, S. Larue-Charlus, F. Severin, N. Becker, and J. R. Schlehofer, J. Med. Virol. 44:215-222, 1994), we did not find solid evidence of its replication in maternal or embryonal tissues from the first trimester of pregnancy. The questions of a potential pathogenic etiology of AAV and the interaction with HSV remain open.

Measles immunity and response to revaccination of a young adult population in Israel

In order to evaluate the true immune status and the effect of revaccination on a young adult population, we collected serum samples from 289 military recruits who were vaccinated during an outbreak in 1991. Most vaccinees, age 18-25 years, had apparently been immunized once before as infants. Sera collected just prior to the vaccination and 14 and 28 days afterwards were tested for measles antibodies by hemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA)-IgM. Before vaccination, 46 (15.9%) of the subjects had no HI antibodies, (< 1:4) and 48 (16.6%) had borderline (1:4) HI titer. Following vaccination, only ten (3.5%) remained negative and 19 (6.6%) had borderline titer. The increase in HI antibody titer was inversely proportional to the prevaccination titer, and 159 subjects (55.0%) showed no increase at all. The geometric mean titer (GMT) rose from 9.14 to 21.47. Among the prevaccination-negative subjects (HI < 1:4) 28 (60.9%) reached a postvaccination titer of > or = 1:8, and eight (17.4%) reached a titer of 1:4. Twelve (26.1%) of the negative subjects seroconverted and developed IgM, 16 (35%) seroconverted without IgM, and 18 (39%) remained negative and did not develop IgM. A group of eight vaccinees with prevaccination titer of > or = 1:4 developed IgM. Some were probably infected by the circulating wild-type virus prior to the vaccination. Thus, a total number of 20 of the 289 subjects studied (6.9%) had true negative preimmune status as judged by the IgM test. However, the vaccination campaign prevented further measles cases, apparently by increasing the population's immunity, particularly in individuals with very low titers or without measles antibodies.

Determination of immunity to measles virus in young adults: comparative evaluation of a commercial enzyme immunoassay and the hemagglutination inhibition techniques

BACKGROUND

Determination of the immune status against measles in young adults requires careful evaluation of the laboratory methods because of waning immunity. The hemagglutination inhibition (HI) test and enzyme-linked immunosorbent assay (ELISA) may lack the sensitivity required to detect very low levels of antibodies. In addition, the correlation between ELISA-IgG assays and the degree of protection from measles is not well defined.

OBJECTIVES

(a) Evaluation of a commonly used measles ELISA-IgG test kit in comparison with the hemagglutination inhibition (HI) test which corresponds strongly to virus neutralization; (b) determination of false negative rates of the ELISA-IgG and the HI tests; (c) evaluation of the ELISA-IgG test kit as a quantitative assay.

STUDY DESIGN

One hundred and eighty serum samples collected from 60 vaccinated young adults immediately before vaccination and 14 and 28 days postvaccination, were tested comparatively by HI and by a commercial ELISA-IgG kit. For evaluation of false negative rates, postvaccination sera of a cohort of 48 vaccinees with negative HI or ELISA-IgG prevaccination sera were tested for IgM. Sixty-three of the samples were also titrated by the ELISA-IgG kit using serial dilutions, for comparison with HI titers.

RESULTS

Using the HI test as a reference method, the ELISA-IgG kit was found to have overall accuracy of 81%, sensitivity of 80% and specificity of 84%. The false negative and the false positive rates were 20% and 16%, respectively. In contrast, when we used postvaccination IgM test to distinguish between true and false prevaccination negatives in both the HI and ELISA-IgG tests, we found that the false negative rates were 75.6% by ELISA and 72.5% by HI, and false positive rates were 2.4% and 0%, respectively. Serum titers determined by the ELISA-IgG test were generally 5-10-fold higher than the corresponding HI titers, but without a consistent correlation.

CONCLUSIONS

Both the ELISA-IgG and the HI tests frequently failed to detect residual immunity. The two tests also did not correlate well with each other suggesting that different antigenic determinants of the virus are involved in each assay and therefore the HI test should not be used as a reference method for evaluation of the sensitivity of ELISA IgG kits.

Serological evidence for hepatitis E virus infection in Israel

Israel is suspected to be endemic for hepatitis E virus (HEV) because of its geographic location and the large-scale immigration from endemic countries. Although no cases of local HEV infection have been diagnosed, a serological survey would provide indirect evidence for such infection. We examined sera from 1,416 healthy subjects, including 1,139 Jews from various regions of Israel and 277 Arabs, most of whom reside in the West Bank of the Jordan River. In addition, we tested 13 non-A, non-B, and non-C viral hepatitis patients. Sera were screened for antibody to hepatitis E virus (anti-HEV) by a newly developed enzyme immunoassay (EIA) and by immunoblots for both IgG and IgM anti-HEV activity. Positive samples were confirmed by neutralization. The seroprevalence found by EIA was 2.81% and 1.81% in the Jewish and Arab populations, respectively. More than a 2-fold higher prevalence in males compared to females and an increase with age were found in both populations. However, these differences were nonsignificant. The geographical distribution was even throughout the country, except for two clusters of 3 and 4 seropositive individuals possibly reflecting past foci of infection. Eight of 37 EIA-positive sera were positive for IgG, and 3 were positive for IgM by the immunoblot assay. Among hepatitis patients (9 acute and 4 chronic), one patient with chronic hepatitis was positive for both IgG and IgM. Our study provides indirect evidence that Israel is endemic for HEV.(ABSTRACT TRUNCATED AT 250 WORDS)

Application of ELISA for IgM, IgA and antigen detection for rapid diagnosis of respiratory syncytial virus infections: a comparative study

BACKGROUND

Infection with Respiratory Syncytial Virus (RSV) can be rapidly diagnosed by detection of viral antigen in nasopharyngeal secretions (NPS) or serologically by detecting IgM and IgA antibodies.

OBJECTIVES

To evaluate the above methods for reliability and rapidity, and compare them with the complement fixation (CF) test and virus isolation.

STUDY DESIGN

Viral antigen was tested in 145 NPS samples by ELISA in parallel with tissue culture isolation. The geometric mean titer (GMT) of complement fixing antibodies in various age groups was determined from 92 individual serum samples by CF test. The diagnostic methods, CF test, ELISA-IgM and ELISA-IgA, were evaluated using 21 pairs of acute and convalescent sera. Appearance of IgM and IgA in serum samples with low or negative CF titers was studied in two age groups: 0-10 months (n = 82), and 11 months-9 years (n = 47).

RESULTS

From the 145 NPS samples, 20 samples were positive by both ELISA and virus isolation, 9 were positive only by ELISA and 5 were positive only by virus isolation. The GMT by age group for 92 sera evaluated by CF test were 40 (0-10 months), 195 (11-24 months), 269 (2-4 years), 173 (5-12 years) and 132 (adults). Among the 21 paired sera examined, CF test detected 13 RSV infections by antibody rise or seroconversion while the ELISA-IgM/IgA tests identified all 21 infections, 7 of them in the first sample. The presence of IgM alone or IgM and IgA antibodies was demonstrated in both age groups examined; however, IgA alone was found only in the age group 11 months and older.

CONCLUSIONS

ELISA for antigen detection is better than virus isolation because it is faster (6-20 h vs. 3-20 days, respectively) and more sensitive (29/34 vs. 25/34 positives, respectively). ELISA-IgM and ELISA-IgA was more sensitive and reliable than the CF test, particularly for the 0-10 month age group. Thus, when necessary, serological diagnosis of RSV infection can be based on the presence of IgM and/or IgA antibodies in serum samples obtained early after onset of symptoms.

Sex differences in the humoral antibody response to live measles vaccine in young adults

BACKGROUND

Following vaccination of children using high-titre live measles vaccine, excess non-specific mortality was reported, particularly among females. Since vaccination with live measles virus results in a temporary depression of the immune response to other antigens, the female predominance in subsequent non-measles mortality may be due to sex differences in response to live measles vaccines.

METHODS

In this study, the immunogenicity of standard titre live Schwarz strain measles vaccine was examined 2 and 4 weeks post-vaccination in 223 males and 66 female aged 18-20 years in Israel in 1991.

RESULTS

Females had higher post-vaccination geometric mean titre (GMT) at all levels of pre-vaccination titres at both 2 and 4 weeks. Furthermore, after controlling for differences in pre-vaccination titres, overall the post-vaccination GMT for females was about 50% higher than for males (P < 0.001).

CONCLUSIONS

These findings indicate that females exhibit a stronger humoral immune response to measles vaccine. Possible sex differences in immunosuppression following measles vaccination should be explored.

Adenovirus type 8 conjunctivitis outbreak in a neonatal intensive care unit

An outbreak of adenovirus type 8 conjunctivitis occurred in seven premature infants who had undergone ophthalmological examination four to seven days previously. Three of the affected infants, treated with steroids because of bronchopulmonary dysplasia, showed systemic manifestations and deterioration of their respiratory disease. Second and third waves affected nine staff and 12 family members.

West Nile fever encephalitis

Three cases of meningoencephalitis caused by the West Nile virus in young people are described. All patients had high fever, severe headaches, and meningeal irritation. One patient had papillitis and a maculopapular rash. Lymphadenopathy, which is a common finding in West Nile fever, was not found in any of our patients. Duration of the disease was one to two weeks, and recovery was complete. Cerebrospinal fluid examination revealed an increase in protein and pleocytosis (predominantly polymorphonuclears). We believe that West Nile encephalitis is not rare in Israel.

Stimulation of antibodies to Epstein-Barr virus (EBV) in acute viral infections

Acute and convalescent sera from 77 patients with serologically confirmed influenza, measles and adenovirus infections and from 36 healthy controls were tested for the level of antibodies to Epstein-Barr (EB) virus. In the three groups of patients significantly higher titers of antibodies to EB viral capsid antigen (VCA) were found as compared to the controls. In 19 patients twofold or higher rise in antibody titers between the first and second blood sample was demonstrated. It is suggested that in patients with influenza, measles or adenovirus infections, involvement of lymphocytes leads to reactivation of EB virus and antibody formation is stimulated.

Latent viruses and Bell's palsy in children

4 children with unilateral facial palsy--Bell's palsy (BP)--had serological evidence of primary infection with Epstein-Barr virus (EBV). Concomitant infection with cytomegalovirus (CMV) was demonstrated in 1 child while in all 4 children a rise in antibody titers to an additional one or two viruses was demonstrated. The viruses involved were herpes simplex, CMV and adenovirus which are latent in humans. Immunosuppression induced by EBV and steroid treatment may cause reactivation of these viruses resulting in rise in antibody titers. The need for prolonged serological follow-up for possible reactivation of latent viruses in BP is emphasized.