Increased mobility and redistribution of concanavalin A receptors on cells infected with Newcastle disease virus

Lectins and their application to clinical microbiology

Lectins are generally associated with plant or animal components, selectively bind carbohydrates, and interact with procaryotic and eucaryotic cells. Lectins have various specificities that are associated with their ability to interact with acetylaminocarbohydrates, aminocarbohydrates, sialic acids, hexoses, pentoses, and as other carbohydrates. Microbial surfaces generally contain many of the sugar residues that react with lectins. Lectins are presently used in the clinical laboratory to type blood cells and are used in a wide spectrum of applications, including, in part, as carriers of chemotherapeutic agents, as mitogens, for fractionation of animal cells, and for investigations of cellular surfaces. Numerous studies have shown that lectins can be used to identify rapidly certain microorganisms isolated from a clinical specimen or directly in a clinical specimen. Lectins have been demonstrated to be important diagnostic reagents in the major realms of clinical microbiology. Thus, they have been applied in bacteriology, mycology, mycobacteriology, and virology for the identification and/or differentiation of various microorganisms. Lectins have been used successfully as epidemiologic as well as taxonomic markers of specific microorganisms. Lectins provide the clinical microbiologist with cost-effective and potential diagnostic reagents. This review describes the applications of lectins in clinical microbiology.

Use of lectins to detect and differentiate subtypes of Marek's disease virus and turkey herpesvirus glycoproteins in tissue culture

Biotinylated lectins in conjunction with an avidin-biotin-peroxidase complex were used for the first time to reveal glycoproteins in chicken and duck embryo fibroblasts infected with three prototype members of the avian herpesvirus group, Marek's disease virus serotypes 1 and 2 and turkey herpesvirus. By using a panel of 10 lectins, a pattern of reactivity emerged which was both group- and type-specific. Morphological details of the lectin-stained cells include cytoplasmic granulation, capping and bleb-like protrusions of the cell membrane. Although no antibody is necessary for the reaction, this novel approach allows specific detection of the glycan moieties of viral glycoproteins as they are synthesized during infection.

Agglutination kinetics of enzymatically treated normal and diabetic rat hepatocytes

The effect of trypsin and neuraminidase treatments on concanavalin A-induced agglutination of viable hepatocytes from normal and diabetic rats are reported. Trypsin (1.0 microgram/mL) treatment resulted in a increased rate of hepatocyte agglutination in both normal and diabetic cells in the presence of 100 micrograms/mL of concanavalin A. However, neuraminidase treatment resulted in a decrease in the rate of cytoagglutination in the normal cells and an increase in the rate in the diabetic counterpart. The results suggest that trypsin may have caused the removal of a surface protein and/or split a peptide bond on the agglutinin receptors resulting in identical receptor exposure and clustering in normal and diabetic cells. The neuraminidase data suggest that the arrangements of the neuraminic acid moieties on the receptors in normal cell membranes were different from those in the diabetic cells, eliminating the possible effect of changes in the surface charge density. In conclusion, normal cells carry numerous clustered (possibly some in the "cryptic" state) agglutinin receptors in the cell membrane as compared with cells from diabetic rats.

Electron microscopic investigations on the upper respiratory tracts of infants and children for detecting viral infections

The upper respiratory tract of 20 infants and children, suffering from viral diseases, have been investigated cytochemically and electron microscopically. We employed the electron microscope negative staining and the concanavalin-A-peroxidase methods in our investigations, besides the usual serological and immunological ones. Concanavalin-A-peroxidase reaction showed a characteristic damaging of the cell-surface which may play an important role in viral infection. The electron microscope negative staining investigations showed adeno-, herpes- and influenza-virions which are referring to viruses. These morphological methods are useful and they increase the efficiency of diagnosing viral infections.

Virus-induced decrease of insulin receptors in cultured human cells

Viral infections may produce abnormalities in carbohydrate metabolism in normal subjects and profound changes in glucose homeostasis in insulin-dependent diabetics. Using an in vitro radio-receptor assay with 125I-labeled insulin and human-amnion (WISH) cells, the effect of viral infections on insulin receptors was examined. Both herpes simplex virus and vesicular stomatitis virus produced a 50% decrease in insulin binding. There was no evidence that this decrease was due to degradation of insulin. On quantitative analysis, this decrease in binding was found to be the result of a decrease in receptor concentration with no change in receptor affinity. The decrease in receptors occurred between 4 and 12 h, at the time viral antigens were being inserted into the plasma membrane of infected cells. Because the t 1/2 of insulin receptors in uninfected cells was between 14 and 24 h, the decrease in insulin receptors cannot be explained solely by virus-induced shut-off of macromolecular synthesis. Moreover, viruses such as encephalomyocarditis that do not insert new antigens into the plasma membrane, did not cause changes in the number of insulin receptors. The most likely explanation is that virus-induced changes in the plasma membrane altered or displaced insulin receptors. It is concluded that the insulin receptor assay is a sensitive and quantitative method for studying the effect of viral infections on cell membranes. These data also suggest that abnormalities in glucose metabolism associated with some viral infections may be due, in part, to changes in the concentration of insulin receptors.

Lectin-mediated agglutination of murine lymphoma cells. Cell surface deformability and reversibility of agglutination by saccharides

Agglutination of S49 mouse lymphoma cells by Ricinus communis I agglutinin can be reversed by the competing haptenic saccharide, lactose, soon after agglutination, but after further incubation in the absence of lectin the agglutination reaction could not be reversed by lactose and the cells remained as multicell aggregates. The irreversibility of S49 cell agglutination was time, temperature and lectin concentration dependent and its onset correlated with ultrastructurally observed deformation of adjacent cell surfaces and an increase in the proportion of adjacent cell surface areas in close apposition within multicell aggregates. Pretreatment of S49 cells with cytochalasin B or cytochalasin B plus vinblastine enhanced R. communis I agglutinin-mediated agglutination, while vinblastine alone and fluoride plus azide had essentially no effect. When drug-treated cells were agglutinated and then incubated in lectin-free drug-containing media for various times prior to lactose addition, the drug effects were more pronounced. Cytochalasin B alone or with vinblastine inhibited lactose reversal of S49 cell agglutination compared to the drug-free controls, while fluoride plus azide enhanced hapten reversibility. Electron microscopic analysis revealed that the onset of agglutination irreversibility correlated with cell surface deformation in the drug-treated cells. Cell aggregates that were more readily reversible by lactose (fluoride plus azide) were unchanged or less deformed, while S49 aggregates treated with cytochalasin B plus vinblastine were more deformed compared to controls without drugs. These experiments suggest a role for cell surface deformability as an important secondary effect during lectin-mediated cell agglutination of S49 lymphoma cells.

Selection and characterization of a varient of murine L5178Y lymphoma resistant to local anesthetics

A varient of murine L5178Y lymphoma resistant to procaine hydrochloride (PH) was selected by exposing the cells to gradual increments of PH in the growth medium until the cell grew exponentially in the presence of 1.5 mM PH. Using cinephotomicrography, it was observed that the majority of cells that initially succumbed to PH failed to undergo successful mitosis. With respect ot chromosomal, cell size distribution and flow microfluorometric analyses, the PH-resistant cells are very similar to a spontaneous tetraploid cell line (R1T) previously cloned. The isolated cells, designated R1/P, were also found to be cross-resistant to analogues of PH, namely, lidocaine, tetracaine and dibucaine. The naturally-occurring tetraploid cell line (R1T) was also found to be more resistant to local anesthetics, although not to the same extent as R1/P cells. Since the enzyme that hydrolyzes procaine appears to be absent in all these lymphoid cell lines, the difference in resistance does not appear to depend on differences in the ability of these cells to remove the agent. It is suggested that an alteration in the structure and/or function of the plasma membrane in R1/P cells have rendered them either less sensitive to the membrane-perturbing effects of the local anesthetics or less permeable to local anesthetics molecules. The ability of local anesthetics to affect membranes and cytoskeleton structures may play a role in the genesis and/or selection of these cell variants.

Transformation by concanavalin A of the response of molluscan neurones to L-glutamate

Concanavalin A causes in all Aplysia and Helix neurones a depolarising response to L-glutamate. The Con A-induced glutamate response is pharmacologically distinct from the three cell-specific glutamate responses (two inhibitory, one excitatory) that can be elicited from untreated molluscan neurones. The transformation in glutamate sensitivity brought about by Con A does not seem to be related to the lectin's capacity to produce redistribution of receptor sites in cell membranes.

Calcium ionophores A23187 and X537A affect cell agglutination by lectins and capping of lymphocyte surface immunoglobulins

The microtubule-disruptive drugs colchicine and vinblastine alter ligand-induced redistribution of cell surface immunoglobulins and lectin receptors. These effects can be duplicated by treatment of cells with the divalent cation ionophores A23187 and X537A. Ionophore activity was dependent upon the presence of Ca2+ (1.8 - 10(-3)-4 - 10(-4) M) in the culture medium. The K+-selective ionophore valinomycin had no effect on ligand-induced redistribution of surface receptors. It is suggested that A23187 and X537A impair membrane-associated microtubules involved in transmembrane control of receptor mobility and topography. In contrast to the action of colchicine and vinblastine that bind directly to microtubules, it is proposed that ionophores indirectly affect microtubules by raising the concentration of Ca2+ in the cytoplasm to levels that favor microtubule depolymerization and inhibit microtubule assembly.

Cell shape changes and transmembrane receptor uncoupling induced by tertiary amine local anesthetic

Tertiary amine local anesthetics (dibucaine, tetracaine, procaine, etc.) modify cell morphology, concanavalin A (Con A)-mediated agglutinability and redistribution of Con A receptors. Con A agglutination of untransformed mouse 3T3 cells was enhanced at low concentrations of local anesthetics, and the dynamics of fluorescent-Con A indicated that ligand-induced clustering was increased in the presence of the drugs. In contast, these drugs inhibited Con A-induced receptor capping on mouse spleen cells. These effects can be duplicated by combinations of vinblastine (or colchicine) and cytochalasin B suggesting that local anesthetics act on microtubule and microfilament assemblies which are involved in the trans-membrane control of cell surface receptor mobility and distribution. It is proposed that tertiary amine local anesthetics displace plasma membrane-bound Ca2+, resulting in disengagement of microfilament systems from the plasma membrane and increased cellular Ca2+ concentration to levels which disrupt microtubular organization. The possible involvement of cellular Ca2+ in cytoskeletal destruction by local anesthetics was investigated utilizing Ca2+-specific ionophores A23187 and X537A. In media containing Ca2+ and cytochalasin B these ionophores caused effects similar to tertiary amine local anesthetics.

Local anesthetics affect transmembrane cytoskeletal control of mobility and distribution of cell surface receptors

Tertiary amine local anesthetics facilitated concanavalin A-induced redistribution of lectin receptors on murine BALB/3T3 cells and enhanced the susceptibility of these cells to agglutination by concanavalin A. In contrast, these drugs at similar concentrations inhibited ligand-induced capping of immunoglobulin receptors on mouse lymphocytes. We propose that these differing effects of local anesthetics on membrane receptor mobility in fibroblasts and lymphocytes result from the action of anesthetics on membrane-associated microtubules and microfilaments involved in the transmembrane control of receptor mobility. We present electron microscopic evidence of structural alterations in microtubule and microfilament organization in anesthetic-treated cells, together with data on changes in the responsiveness of anesthetic-treated cells to drugs that act on microtubules and/or microfilaments. This evidence supports the proposal that anesthetics affect the organization of cytoskeletal components or their plasma membrane attachment points. The effects of local anesthetics on ligand-induced redistribution of membrane receptors in both 3T3 cells and lymphocytes can be duplicated by treating cells with colchicine (or Vinca alkaloids) together with cytochalasin B. We propose that the participation of membrane-associated microtubules and microfilaments in the transmembrane control of receptor mobility is such that microtubules and microfilaments play opposing roles in regulating the mobility and topography of cell surface receptors.

Effects of local anesthetics on membrane properties. II. Enhancement of the susceptibility of mammalian cells to agglutination by plant lectins

Treatment of untransformed mouse and hamster cells with the tertiary amine local anesthetics dibucaine, tetracaine and procaine increases their susceptibility to agglutination by low doses of the plant lectin concanavalin A. Agglutination of anesthetic-treated untransformed cells by low doses of concanavalin A is accompanied by redistribution of concanavalin A receptors on the cell surface to form patches, similar to that occurring in spontaneous agglutination of virus-transformed cells by concanavalin A. Immunofluorescence and freeze-fracture electronmicroscopic observations indicate that local anesthetics per se do not induce this redistribution of concanavalin A receptors but modify the plasma membrane so that receptor redistribution is facilitated on binding of concanavalin A to the cell surface. Fluorescence polarization measurements on the rotational freedom of the membrane-associated probe, diphenylhexatriene, indicate that local anesthetics produce a small increase in the fluidity of membrane lipids. Spontaneous agglutination of transformed cells by low doses of concanavalin A is inhibited by colchicine and vinblastine but these alkaloids have no effect on concanavalin A agglutination of anesthetic-treated cells. Evidence is presented which suggests that local anesthetics may impair membrane peripheral proteins sensitive to colchicine (microtubules) and cytochalasin-B (microfilaments). Combined treatment of untransformed 3T3 cells with colchicine and cytochalasin B mimics the effect of local anesthetics in enhancing susceptibility to agglutination by low doses of concanavalin A. A hypothesis is presented on the respective roles of colchicine-sensitive and cytochalasin B-sensitive peripheral membrane proteins in controlling the topographical distribution of lectin receptors on the cell surface.

Cell rigidity: Effect on concanavalin A-mediated agglutinability of fibroblasts after fixation

A quantitative hemadsorption assay distinguishes the effects of membrane fixation on concanavalin A-mediated agglutinability of fixed cells with unfixed cells. We observed undiminished adherence of unfixed erythrocytes to glutaraldehyde-fixed normal and virus-transformed hamster fibroblasts coated with concanavalin A. Fixation of the erythrocytes abolished agglutination with fixed fibroblasts. The agglutinability of fixed cells is more likely related to increased cell rigidity than to decreased membrane fluidity.

Interaction of Lens culinaris lectin, concanavalin A, Ricinus communis agglutinin and wheat germ agglutinin with the cell surface of normal and transformed rat liver cells

The observation of BOREK et al. (1973) on nonagglutinability of transformed rat liver cells by Lens culinaris lectin and our ultrastructural findings of a greater mobility of the Lens culinaris lectin receptors on transformed rat liver cells as compared to normal rat liver cells (ROTH 1975) initiated the present agglutination experiments on liver cells with lectins. For agglutination assay the microhemadsorption technique after FURMANSKI et al. (1973) was used with exception of several tests on EDTA-detached cells. The transformed rat liver cells exhibited, in contrast to the findings of BOREK et al. (1973), a positive microhemadsorption with Lens culinaris lectin as well as with Concanavalin A, Ricinus communis lectin and wheat germ agglutinin whereas the normal rat liver cells became positive only after a brief trypsin treatment. The significance of the difference in agglutinability of rat liver cells with Lens culinaris lectin and the other lectins used is discussed with regard to the cell-cell interaction mediated by lectins.

Effects of concanavalin A on mouse peritoneal macrophages. II. Metabolism of endocytized proteins and reversibility of the effects by mannose

The half-time for the degradation of horseradish peroxidase (HRP) is increased from 14 h to 37 h in Con A-treated cells, while the half-time for the degradation of [(125)I]BSA is increased from 5.4 h to 14.8 h. This supports prior microscopic observations which suggested that Con A pinosomes showed a marked impairment in their ability to form phagolysosomes. Artifacts due to anomalous behavior of HRP-Con A complexes, or to inhibition of lysosomal hydrolases by Con A, could be excluded. These indications of impaired phagolysosome formation, as well as those described in the preceding paper, could be reversed by postincubation of the cells in mannose, but not in galactose. This reversal is accompanied by a dissociation of Con A-FITC from the inner surface of the pinosome membrane, into the vesicle contents. These observations may be relevant to the ability of Con A to affect several membrane characteristics, and are also of interest in relation to the impaired formation of phagolysosomes which has been described in certain in vitro parasitic infections of macrophages or other cells.

Primaquine diphosphate: inhibition of Newcastle disease virus replication

The response of Newcastle disease virus replication to primaquine, an antimalarial drug, was examined in chicken embryo cells (CEC). Virus-induced hemadsorption was completely inhibited by 250 mug of primaquine per ml. At lower concentrations, hemadsorption inhibition was dose dependent. Primaquine retarded virus-induced redistribution of receptor sites on the host cell plasma membrane as shown by the failure of infected, drug-treated CEC to be agglutinated with concanavalin A. The production of infectious progeny virus was substantially inhibited by the addition of primaquine at various times postinfection. When the drug was added early in the virus replication cycle, viral ribonucleic acid (RNA) synthesis was inhibited; however, when the drug was added late in the cycle, stimulation of RNA synthesis was observed. Primaquine was also shown to retard the incorporation of [(14)C]amino acids into proteins of virus-infected CEC. We suggest that the major role of primaquine is inhibition of protein synthesis; this results in changes in: hemadsorption, redistribution of lectin receptors, release of progeny, and virus-induced RNA synthesis.