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Petunia plants collected in Sao Paulo City, Brazil, showing yellow mosaic, were naturally infected by a virus of the genus Tobamovirus identified according to particle morphology and size, host range, physical properties and cytopathic effects. On the basis of serological properties, amino acid composition and nucleotide sequence of the coat protein gene, the virus isolate was identified as a new strain of Tobacco mosaic virus (TMV-p). A conspicuous feature of this virus infection is the presence of virus-like particles within the mitochondrial matrix. The data from phylogenetic analysis indicate that TMV-p belongs to subgroup 1 of the genus Tobamovirus. Zusammenfassung In Sao Paulo Stadt, Brasilien, wurden Petunia-Pflanzen gesammelt, die Gelbmosaiksymptome zeigten. Es konnte nach der Partikelmorphologie und -grose, sowie dem Wirtsspektrum, den physiologischen Eigenschaften und cytopathologischen Einflussen nachgewiesen werden, dass es sich um eine naturliche Infektion mit einem Tobamovirus handelte. Anhand der serologischen Eigenschaften, der Aminosaurezusammensetzung und der Nukleotidsequenz des Hullproteins wurde das Virus als eine neue Art des Tabak Mosaik Virus (TMV-p) bestimmt. Eine Besonderheit dieser Virusinfektion ist das Vorhandensein von virusahnlichen Partikeln innerhalb der mitochondrialen Matrix. Die Daten der phylogenetischen Analyse deuten darauf hin, dass TMV-p der Subgruppe 1 dem Genus Tobamovirus angehort.

The introduction in 1990 of a new biosensor technology based on surface plasmon resonance has greatly simplified the measurement of binding interactions in biology. This new technology known as biomolecular interaction analysis makes it possible to visualize the binding process as a function of time by following the increase in refractive index that occurs when one of the interacting partners binds to its ligand immobilized on the surface of a sensor chip. None of the reactants needs to be labelled, which avoids the artefactual changes in binding properties that often result when the molecules are labelled. Biosensor instruments are well-suited for the rapid mapping of viral epitopes and for identifying which combinations of capturing and detector Mabs will give the best results in sandwich assays. Biosensor binding data are also useful for selecting peptides to be used in diagnostic solid-phase immunoassays. Very small changes in binding affinity can be measured with considerable precision which is a prerequisite for analyzing the functional effect and thermodynamic implications of limited structural changes in interacting molecules. On-rate (ka) and off-rate (kd) kinetic constants of the interaction between virus and antibody can be readily measured and the equilibrium affinity constant K can be calculated from the ratio ka/kd = K.

Earlier electron microscopy studies of the location of various antigenic sites in tobacco mosaic virus indicated that epitopes specific for the quaternary structure and absent in dissociated viral subunits (so-called neotopes) were present along the entire length of the virus particle. In contrast, epitopes expressed in both intact particles and dissociated subunits (so-called metatopes) were found only at the one extremity of the particle containing the 5' end of the RNA. In the present study, the binding properties of antibodies to neotopes and metatopes were studied with the BIAcore. From the results of capture assays with viral subunits and on the basis of binding stoichiometry calculations, it was possible to demonstrate the presence of neotope and metatope specificities on additional parts of the viral surface where they had not been identified before by classical immunoassays. In two site binding assays it was also found that a neotope specificity could be induced in dissociated viral subunits by the binding of a first antimetatope antibody. The results clearly demonstrated the superiority of the biosensor technology for mapping conformational epitopes in viral proteins.

Summary Three manufacturing procedures using a slow propeller mixer, a labyrinth and a valve homogenizer were used for the preparation of emulsions. Three oil phases and fifteen pairs of emulsifiers were used giving a range of HLB values. These homogenizers gave more stable emulsions than the propeller mixer in the majority of cases although several times the reverse was the case. To interpret these reversals several mechanisms are suggested: the mechanical engergy applied to the system modifies the equilibrium of the interaction oil/emulsifier; homogenization gives a considerable increase in the contact to the point where the interfacial film is deficient in surface agents and is unable to stablilise completely the system or the emulsifier is no longer in sufficient concentration in the aqueous phase to play its role in viscosity modification which appears to be the case in non homogenized emulsions.

Synopsis The influence of the following hydrophilic polymers on the stability of emulsions has been studied: sodium carboxymethyl cellulose, hydroxyethyl cellulose, agar-agar, water dispersible clay, and a neutralized polyethylene acid. The oil phases used were paraffin oil, olive oil and a synthetic C(8)-C(12) triglyceride. The other emulsifiers were non ionic-types. After 12 months storage at room temperature, olive oil proved to be the most difficult material to emulsify. The hydrocolloids did not give uniformly better stability to the emulsions and the polyacrylic acid gave the best stability of the colloids tested.

Synopsis With high-performance liquid chromatography the three major isomers present in the sunscreen agent, 5(3, 3-dimethyl-2-norbornylidene)-3 pentene-2-one, have been isolated and quantified. Their structures have been determined using mass, infra-red, and NMR spectrometry. Isomeres dans le filtre solaire 5(3, 3-dimethyl-2-norbornylidene)-3 pentene-2-one.

Two panels of monoclonal antibodies (Mabs) raised against duck (Barbary) egg white lysozyme or hen egg white lysozyme, were tested in antigen-coated plate (ACP) and double antibody sandwich (DAS) ELISA for cross-reaction with various avian lysozymes. The antibodies to hen lysozyme cross-reacted with goose lysozyme, but most antibodies to duck lysozyme reacted with it. One antibody to duck lysozyme reacted more strongly with goose lysozyme than with the homologous antigen, a heterospecific reaction confirmed by biosensor technology. Many lysozyme epitopes recognized by different antibodies showed considerable resistance to heat denaturation. Such Mabs may be useful for detecting chicken liver adulterants in “foies gras” of goose or duck origin.

The antigenic activity of the N-terminal region of coat protein of turnip mosaic virus (TuMV) aphid transmissible strain 1 and non-transmissible strain 31 was examined by using a panel of monoclonal antibodies (MAbs) raised against the two virus strains as well as antisera raised against several synthetic peptides from the N-terminal region of the protein. The reactivity of these antibodies was tested in ELISA and in a biosensor system (BIAcore Pharmacia) using virus particles, dissociated coat protein and synthetic peptides as antigens. Substitution of a single amino acid at position 8 in the coat protein of TuMV strain 1 abolished any cross-reactivity between MAbs to strain 1 and the substituted peptide (strain 31) in ELISA although some cross-reactivity was apparent in BIAcore inhibition experiments. In reciprocal tests with MAbs to strain 31 no cross-reactivity with the heterologous peptide was detected in either type of assay. The amino acid residue present at position 8 appears to play a critical role in the binding capacity of MAbs specific for the N-terminal region of TuMV. Antiserum to a synthetic peptide corresponding to residues 1–14 of the protein of TuMV strain 1 was found to react strongly with dissociated coat protein and intact virus particles and was able to inhibit the aphid transmission of the virus. Antiserum to the corresponding peptide of strain 31 did not have this capacity.

The different types of epitopes found in viral antigens are described. The BIAcore has been used successfully to map the location of epitopes in viral antigens and several examples of such studies are presented. Knowledge of the affinity of viral antibodies is important for understanding the molecular basis of viral antigenicity and the mechanism of infectivity neutralization by antibodies. The use of the BIAcore for measuring binding constants of viral antibodies is described. Affinity constants of antibodies binding to virus particles are easily obtained using sensor chips on which the virus is immobilized by a first layer of antibodies. Affinity constants obtained with the BIAcore agree closely with values obtained by several other methods of affinity determination. By comparing the binding properties of neutralizing and nonneutralizing viral antibodies with the BIAcore, it should be possible to establish whether there is a relationship between affinity and neutralizing capacity of antibodies. By immobilizing synthetic peptides corresponding to viral epitopes on sensor chips, the BIAcore can also be used to quantitate antibody to specific epitopes present in polyclonal antiserum.

It has been shown by others that translation of tobacco mosaic virus (TMV) RNA may begin before uncoating of particles is complete. We provide evidence that this cotranslational disassembly can be inhibited by incubating TMV treated at pH 8 with certain monoclonal antibodies (MAbs) specific for TMV coat protein. The most efficient inhibition was achieved by incubation with some anti-metatope MAbs known to bind to the TMV extremity that becomes disassembled first and contains the 5′ end of the RNA, as well as with some anti-cryptotope MAbs that bind only to dissociated coat protein subunits.

Resume Afin d'ameliorer la stabilite des emulsions a base d'huile de paraffine, d'huile d'olive, de Myglyol 812 et de plusieurs couples emulsifiants constitues de tensio-actifs non-ioniques, cinq polymeres hydrophiles ont ete utilises: la carboxymethyl cellulose sodique, l'hydroxyethyl cellulose, l'agar-agar, une argile hydrophile synthetique et un polymere carboxyvinylique. Apres douze mois de conservation, il ressort un certain nombre de points: parmi les trois huiles utilisees l'emulsion a base d'huile d'olive se revele etre la plus difficile a stabiliser. L'addition d'un hydrocolloide n'entraine pas forcement la stabilisation d'une emulsion et parmi les additifs testes c'est le polymere acrylique qui se revele etre le plus efficace. Stabilisation of emulsions: influence of hydrophilic colloids Synopsis The influence of the following hydrophilic polymers on the stability of emulsions has been studied: sodium carboxymethyl cellulose, hydroxyethyl cellulose, agar-agar, water dispersible clay, and a neutralized polyethylene acid. The oil phases used were paraffin oil, olive oil and a synthetic C8–C12 triglyceride. The other emulsifiers were non ionic-types. After 12 months storage at room temperature, olive oil proved to be the most difficult material to emulsify. The hydrocolloids did not give uniformly better stability to the emulsions and the polyacrylic acid gave the best stability of the colloids tested.

Summary Three manufacturing procedures using a slow propeller mixer, a labyrinth and a valve homogenizer were used for the preparation of emulsions. Three oil phases and fifteen pairs of emulsifiers were used giving a range of HLB values. These homogenizers gave more stable emulsions than the propeller mixer in the majority of cases although several times the reverse was the case. To interpret these reversals several mechanisms are suggested: the mechanical engergy applied to the system modifies the equilibrium of the interaction oil/emulsifier; homogenization gives a considerable increase in the contact to the point where the interfacial film is deficient in surface agents and is unable to stablilise completely the system or the emulsifier is no longer in sufficient concentration in the aqueous phase to play its role in viscosity modification which appears to be the case in non homogenized emulsions.

Synopsis Le present travail a eu pour but de comprendre les phenomenes regissant la stabilite des emulsions H/E a base d'huile d'olive et de tensio actifs non ioniques. Ces surfactifs ont ete utilises en association (un emulsif hydrophile/un emulsif lipophile) de facon a obtenir une gamme de valeurs HLB s'etendant de 7 a 12. Dans ces conditions l'emulsification de l'huile d'olive n'a ete possible que dans le cas ou l'emulsif lipophile du couple comportait une chaine stearique, isostearique ou stearylique, et lorsque l'emulsif hydrophile possedait une chaine hydrophile de poids moleculaire moyen (400 < PM < 600). Ces resultats tendent a confirmer la theorie selon laquelle la stabilite des emulsions est favorisee par un film interfacial de type lamellaire. Ce travail a egalement permis de mettre en evidence la fragilite de la notion de HLB critique dans le cas de l'huile d'olive. Emulsification of vegetable oils: application to olive oil