Microarray-based molecular detection of foot-and-mouth disease, vesicular stomatitis and swine vesicular disease viruses, using padlock probes

The World Organization for Animal Health (Office International des Epizooties, OIE) includes the diseases caused by foot-and-mouth disease virus (FMDV), swine vesicular disease virus (SVDV), and vesicular stomatitis virus (VSV), as "Diseases Notifiable to the OIE". Foot-and-mouth disease (FMD) outbreaks have severe economical as well as social effects and cannot be differentiated from the diseases caused by the other two viruses on the basis of clinical symptoms. Efficient laboratory techniques are therefore required for detection and identification of the viruses causing similar vesicular symptoms in swine. A rapid method is described using padlock probes and microarrays to detect simultaneously and differentiate the three viruses in a single reaction, as well as providing serotype information in cases of VSV infection. The padlock probe/microarray assay detected successfully and identified 39 cDNA samples of different origin representing the three viruses. The results were in complete agreement with identities and serotypes determined previously. This novel virus detection method is discussed in terms of usefulness and further development.     

Cyclosporin a permits the distinction between specific T and NK activity generated in a human MLC

Human lymphocytes, activated in mixed lymphocyte culture (MLC), express cytolytic activity against a range of target cell types. Cyclosporin A (CyA) efficiently prevents the development of cytotoxic T cells directed against target cells expressing the phenotype of the stimulator cells whilst not preventing an increase in natural killing (NK) activity measured against tumor targets. The drug was further shown not to influence the short-term induction of increased NK activity by interferon. Already established T killer cells are not sensitive to CyA. The drug thus seems to be selectively involved in the induction of immune responses requiring T-cell proliferation.     

Consulting the source code: prospects for gene-based medical diagnostics

Gene-based diagnostics has been slow to enter medical routine practice in a grand way, but it is now spurred on by three important developments: the total genetic informational content of humans and most of our pathogens is rapidly becoming available; a very large number of genetic factors of diagnostic value in disease are being identified; and such factors include the identity of genes frequently targeted by mutations in specific diseases, common DNA sequence variants associated with disease or responses to therapy, and copy number alterations at the level of DNA or RNA that are characteristic of specific diseases. Finally, improved methodology for genetic analysis now brings all of these genetic factors within reach in clinical practice. The increasing opportunities for genetic diagnostics may gradually influence views on health and normality, and on the genetic plasticity of human beings, provoking discussions about some of the central attributes of genetics.     

Cancer diagnostics based on plasma protein biomarkers: hard times but great expectations

Cancer diagnostics based on the detection of protein biomarkers in blood has promising potential for early detection and continuous monitoring of disease. However, the currently available protein biomarkers and assay formats largely fail to live up to expectations, mainly due to insufficient diagnostic specificity. Here, we discuss what kinds of plasma proteins might prove useful as biomarkers of malignant processes in specific organs. We consider the need to search for biomarkers deep down in the lowest reaches of the proteome, below current detection levels. In this regard, we comment on the poor molecular detection sensitivity of current protein assays compared to nucleic acid detection reactions, and we discuss requirements for achieving detection of vanishingly small amounts of proteins, to ensure detection of early stages of malignant growth through liquid biopsy.

Abbreviations

ACPP

acid phosphatase

AFP

alpha‐fetoprotein

CEA

carcinoembryonic antigen

CTLA4

cytotoxic T lymphocyte‐associated protein 4

FDA

(US) Food and Drug Administration

GTEx project

Genotype‐Tissue Expression project

HCA

human cell Atlas

IL‐6

interleukin 6

PD‐1

programmed cell death 1 receptor

PD‐L1

programmed cell death ligand 1

PSA

prostate‐specific antigen

TCGA

The Cancer Genome Atlas

     

Inherited IFNAR1 Deficiency in a Child with Both Critical COVID-19 Pneumonia and Multisystem Inflammatory Syndrome

Journal of Clinical Immunology - Inborn errors of immunity (IEI) and autoantibodies to type I interferons (IFNs) underlie critical COVID-19 pneumonia in at least 15% of the patients, while the...     

Selected Abstracts from the 13th Annual Meeting of the Clinical Immunology Society: 2022 Annual Meeting: Immune Deficiency and Dysregulation North American Conference

Journal of Clinical Immunology - Coronavirus disease 2019 (COVID-19) exhibits a wide spectrum of clinical manifestations, ranging from asymptomatic to critical conditions. Understanding the...     

Use of proximity ligation to screen for inhibitors of interactions between vascular endothelial growth factor A and its receptors

BACKGROUND: Improved methods are required to screen drug candidates for their influences on protein interactions. There is also a compelling need for miniaturization of screening assays, with attendant reductions in reagent consumption and assay costs. METHODS: We used sensitive, miniaturized proximity ligation assays (PLAs) to monitor binding of vascular endothelial growth factor A (VEGF-A) to 2 of its receptors, VEGFR-1 and VEGFR-2. We measured the effects of proteins and low molecular weight compounds capable of disrupting these interactions and compared the results with those obtained by immunoblot analysis. We analyzed 6 different inhibitors: a DNA aptamer, a mixed DNA/RNA aptamer, a monoclonal VEGF-A neutralizing antibody, a monoclonal antibody directed against VEGFR-2, a recombinant competitive protein, and a low molecular weight synthetic molecule. RESULTS: The PLAs were successful for monitoring the formation and inhibition of VEGF-A-receptor complexes, and the results correlated well with those obtained by measuring receptor phosphorylation. The total PLA time is just 3 hours, with minimal manual work and reagent additions. The method allows evaluation of the apparent affinity [half-maximal inhibitory concentration (IC(50))] from a dose-response curve. CONCLUSIONS: The PLA may offer significant advantages over conventional methods for screening the interactions of ligands with their receptors. The assay may prove useful for parallel analyses of large numbers of samples in the screening of inhibitor libraries for promising agents. The technique provides dose-response curves, allowing IC(50) values to be calculated.     

Profiling protein expression and interactions: proximity ligation as a tool for personalized medicine

Abstract. Blokzijl A, Friedman M, Pontén F, Landegren U (From the Department of Genetics and Pathology, Uppsala University, Uppsala, Sweden). Profiling protein expression and interactions: proximity ligation as a tool for personalized medicine. (Review) J Intern Med 2010; 268 : 232–245. The ability to detect very low levels of expressed proteins has enormous potential for early diagnostics and intervention at curable stages of disease. An extended range of targets such as interacting or post‐translationally modified proteins can further improve the potential for diagnostics and patient stratification, and for monitoring response to treatment. These are critical building blocks for personalized treatment strategies to manage disease. The past few decades have seen a remarkably improved understanding of the molecular basis of disease in general, and of tumour formation and progression in particular. This accumulated knowledge creates opportunities to develop drugs that specifically target molecules or molecular complexes critical for survival and expansion of tumour cells. However, tumours are highly variable between patients, necessitating the development of diagnostic tools to individualize treatment through parallel analysis of sets of biomarkers. The proximity ligation assay (PLA) can address many of the requirements for advanced molecular analysis. The method builds on the principle that recognition of target proteins by two, three or more antibodies can bring in proximity DNA strands attached to the antibodies. The DNA strands can then participate in ligation reactions, giving rise to molecules that are amplified for highly sensitive detection. PLA is particularly well suited for sensitive, specific and multiplexed analysis of protein expression, post‐translational modifications and protein–protein interactions. The analysis of this extended range of biomarkers will prove critical for the development and implementation of personalized medicine.     

Defective N-sulfation of heparan sulfate proteoglycans limits PDGF-BB binding and pericyte recruitment in vascular development

During vascular development, endothelial platelet-derived growth factor B (PDGF-B) is critical for pericyte recruitment. Deletion of the conserved C-terminal heparin-binding motif impairs PDGF-BB retention and pericyte recruitment in vivo, suggesting a potential role for heparan sulfate (HS) in PDGF-BB function during vascular development. We studied the participation of HS chains in pericyte recruitment using two mouse models with altered HS biosynthesis. Reduction of N-sulfation due to deficiency in N-deacetylase/N-sulfotransferase-1 attenuated PDGF-BB binding in vitro, and led to pericyte detachment and delayed pericyte migration in vivo. Reduced N-sulfation also impaired PDGF-BB signaling and directed cell migration, but not proliferation. In contrast, HS from glucuronyl C5-epimerase mutants, which is extensively N- and 6-O-sulfated, but lacks 2-O-sulfated L-iduronic acid residues, retained PDGF-BB in vitro, and pericyte recruitment in vivo was only transiently delayed. These observations were supported by in vitro characterization of the structural features in HS important for PDGF-BB binding. We conclude that pericyte recruitment requires HS with sufficiently extended and appropriately spaced N-sulfated domains to retain PDGF-BB and activate PDGF receptor beta (PDGFRbeta) signaling, whereas the detailed sequence of monosaccharide and sulfate residues does not appear to be important for this interaction.     

Automated DNA diagnostics using an ELISA-based oligonucleotide ligation assay.

DNA diagnostics, the detection of specific DNA sequences, will play an increasingly important role in medicine as the molecular basis of human disease is defined. Here, we demonstrate an automated, nonisotopic strategy for DNA diagnostics using amplification of target DNA segments by the polymerase chain reaction (PCR) and the discrimination of allelic sequence variants by a colorimetric oligonucleotide ligation assay (OLA). We have applied the automated PCR/OLA procedure to diagnosis of common genetic diseases, such as sickle cell anemia and cystic fibrosis (delta F508 mutation), and to genetic linkage mapping of gene segments in the human T-cell receptor beta-chain locus. The automated PCR/OLA strategy provides a rapid system for diagnosis of genetic, malignant, and infectious diseases as well as a powerful approach to genetic linkage mapping of chromosomes and forensic DNA typing.