Improved hemagglutination and hemagglutination-inhibition tests for Akabane virus using formalinized goose erythrocytes

When formalinized instead of fresh goose erythrocytes were used in the hemagglutination (HA) test system of the Akabane virus, the agglutinability of the erythrocytes increased and became less salt-dependent. The improved method based on these findings should facilitate the hemagglutination-inhibition (HI) test and may be useful for epidemiological studies of the Akabane virus.     

Immunologic response ot introduction of intact and formalinized erythrocytes]

Experiments were conducted on mice; there was revealed an increase in the immunogenicity of erythrocytes following their immunization illustrated by the difference in the circulating antibody titres and the plaque count in the spleen of the animals, and also by the results of immunization with formalin-treated erythrocytes mixed with the cells of the peritoneal exudate. A conclusion was drawn on the expediency of the immunization with formalinized erythrocytes of rabbits--producers of the hemolytic serum.     

Agglutinin from Limulus polyphemus. Purification with formalinized horse erythrocytes as the affinity adsorbent.

We have purified an agglutinin from the hemolymph of Limulus polyphemus about 1500-3000-fold by adsorption to formalinized horse erythrocytes, elution with N-acetylneuraminic acid and subsequent fractionation on Sephadex G-200. Recovery was in the range of 50 percent. On ultracentrifugation the agglutinin behaves as an homogenous protein with a molecular weight of about 460 000. On polyacrylamide gel electrophoresis of the dissociated protein in sodium dodecylsulfate we found a single prominent diffuse band with an apparent molecular weight of 22 000 plus or minus 2000. This band contained carbohydrate as determined by periodic acid-Schiff staining. The intensity of staining compared with standards suggested a carbohydrate content of less than 4 percent. The protein contains a preponderance of acidic amino acids and has an isoelectric point of 4.83.5 residues per 1000 of glucosamine were detected on amino acid analysis. Agglutination of formalinized horse erythrocytes by the purified protein is inhibited not only by N-acetylneuraminic acid but also by D-glucuronic acid; but not by a number of other monosaccharides. D-Glucuronic acid may be used in place of N-acetylneuraminic acid as the eluting sugar in the purification procedure.     

Isolation of lectins from hemolymph of decapod crustaceans by adsorption on formalinized erythrocytes

Hemolymph of decapod crustaceans contains lectins of important specificity. An isolation procedure, based on adsorption of hemolymph lectins on red blood cells (RBC) fixed with formaldehyde, is described. Hemolymph is let to clot for 3 h at 22-28 degrees C (RT) and for 24 h at 5 degrees C; centrifuged at 13000 g for 30 min; filtered through 5-microm filters; diluted with an equal volume of 50 mM NaCl, 100 mM CaCl(2); supplemented with protease as well as phenoloxidase inhibitors; centrifuged at 13000 g for 20 min. Formalinized RBC (FRBC) are mixed with diluted hemolymph to a suspension of about 20% v/v FRBC. After incubation for 30 min at RT, FRBC are washed five times with 150 mM NaCl, 10 mM CaCl(2). The lectins adsorbed on FRBC are desorbed using either 100-500 mM of carbohydrate solutions in 0.9% NaCl or 50 mM Tris-HCl buffer, pH 8.0 containing 100 mM NaCl and 20 mM entylenediaminetetraacetate (EDTA). The procedure is efficient in isolating the hemolymph lectins of the decapods Liocarcinus depurator and Potamon potamios.     

A possible mechanism for the action of some myxoviruses

Summary The redox properties of some myxoviruses [Fowl plaque virus strain Rostock (FPV), New Castle Disease virus strain Italy (NDV), B/Hong Kong, A/Port Chalmers, A/Victoria, A/Scotland, and A/Fort Dix (FD)] have been investigated by means of electron spin resonance (ESR) and electron microscopic studies as well as by the determination of the hemagglutination (HA) titer (antigen efficiency). The results have shown that viruses decrease the spin concentration of Cu²⁺ by acting as a reducing species (electron donor) which will result in the inactivation (oxidation) of the virus. Addition of an oxidizing substance, such as H₂O₂, to a virus suspension also leads to an oxidation of the viruses and, thus, to their inability to reduce Cu²⁺. This result is confirmed by the decrease of the HA titer of viruses with increasing Cu²⁺ concentrations. H₂O₂ could not be applied for the HA titer test since it interacts with the erythrocytes of the chicken blood used for this determination. Therefore, another oxidizing substance (oxidized glutathione, GSS) was selected which exhibited a slightly less pronounced effect than Cu²⁺. Since reduced glutathione (GSH) exerts a similar but less pronounced effect than GSS, it might be concluded that viruses have a redox system of their own and act as reducing or oxidizing substance depending on the biological receptor system. Electron microscopic studies confirm this hypothesis. As can be seen by the electron micrographs, increasing concentrations of either Cu²⁺, GSS, H₂O₂, KMnO₄, or GSH will, finally, result in a complete destruction of the virus. Because of structural similarities it might be assumed that other types of viruses behave very similarly.     

Opsonic activity of antisera to ribosomal vaccine fractions with live and formalinized Pseudomonas aeruginosa

The opsonic capacity of antisera to Pseudomonas aeruginosa ribosomal vaccine fractions was determined by a chemiluminescent technique. Antiserum to a vaccine fraction ("peak A") containing lipopolysaccharide (antiserum A), and antiserum to a vaccine fraction ("peak B"), which did not contain detectable amounts of lipopolysaccharide (antiserum B), were used to opsonify live or formalin-treated bacteria. Polymorphonuclear leukocytes were then stimulated by the opsonified bacteria in the presence of the chemiluminigenic probe, luminol, resulting in the observed chemiluminescence. The data obtained indicated that the antisera had comparable opsonic activity with live (untreated) bacteria. However, antiserum B had far less opsonic activity than did antiserum A when formalinized bacteria were used. Owing to the effects of formaldehyde on protein, these results were interpreted as evidence to suggest that the opsonic activities of the two antisera are dependent on different antigens on the bacterial cell surface. Antiserum A activity is probably dependent on lipopolysaccharide to a great extent, whereas antiserum B activity is most likely dependent primarily on a protein(s).     

The interaction of fetuin with phosphatidylcholine monolayers. Characterization of a lipoprotein membrane system suitable for the attachment of myxoviruses

1. An artificial membrane system was formed by spreading at air/water and oil/water interfaces, by using phosphatidylcholine and the glycoprotein fetuin (mol.wt. 48400). 2. The plot of increase of interfacial pressure against amount of protein added beneath a monomolecular film of phosphatidylcholine showed two discontinuities, corresponding to the completion of two distinct layers of protein: (a) largely denatured and closely associated with the polar head groups of phosphatidylcholine, possibly with penetration of non-polar protein groups between the phosphatidylcholine molecules and (b) an additional adsorbed layer of substantially native fetuin in either a close-packed or open-lattice array. A more compactly organized membrane was apparently formed at pH7.4 with 1mm-Mg²⁺ in the aqueous phase than without Mg²⁺; at 15mm-Mg²⁺, more random adsorption of protein appeared to take place. Qualitatively similar results were obtained at pH5.1 with 1mm-Mg²⁺. Closer initial packing of the phosphatidylcholine layer decreased both the magnitude of the interfacial pressure change and the amounts of protein bound in the two layers. 3. The amount of N-acetylneuraminic acid released by neuraminidase (EC 3.2.1.18) in the subphase was measured at pH5.1; a mean distribution of 9.7×10¹³ residues/cm² was calculated for the completed second protein layer.