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R Demarco de Hormaeche

Publications and source records attributed to R Demarco de Hormaeche.

23 records · Page 2Linked to original sources
PubMed1987

An attenuated aroA Salmonella typhimurium vaccine elicits humoral and cellular immunity to cloned beta-galactosidase in mice.

beta-Galactosidase (GZ) is an intracellular protein that is frequently used to express cloned antigens as fusion proteins in Escherichia coli. Salmonella typhimurium strain SL3261, an attenuated aroA vaccine strain, was used as a carrier for the plasmid pXY411, which directs the expression of GZ in salmonellae (which do not normally produce this protein). The resulting strain--SL3261(pXY411)--expressed GZ as an intracellular antigen. The plasmid was stable in vitro and in vivo and did not significantly alter the behavior of strain SL3261 in mice. Animals intravenously vaccinated with this construct developed circulating antibodies to GZ, as measured by ELISA, and delayed hypersensitivity to the antigen injected in the footpad. These results indicate that attenuated salmonellae may be expected to elicit both humoral and cellular responses to intracellular cloned antigens.

Animals↗
PubMed1986

Definition of a virulence-related antigen of Neisseria gonorrhoeae with monoclonal antibodies and lectins.

Variants of one strain of Neisseria gonorrhoeae, grown in vivo or in vitro, that have been previously shown to differ in infectivity, serum resistance, and capsule production were compared with use of monoclonal antibodies and lectins. Monoclonal antibodies to virulent gonococci recognized an antigenic site of the lipopolysaccharide (LPS) produced in large amounts by gonococci grown in vivo but present only in a small proportion of in vitro-grown gonococci. This antigen (C-LPS) was found in all 85 different gonococcal isolates studied but not among nonpathogenic neisseriae. It was shared by group B and C meningococci but not by groups A and D. Enzyme-linked immunosorbent assay and Western blot analysis showed that N-acetylglucosamine and N-acetylgalactosamine form part of the epitope. The C-LPS antigen was shown by immunofluorescence to be present on the surface of the gonococci and also free as slime. This antigen appears to confer resistance to killing by normal sera.

Animals↗
PubMed1983

Surface antigens of gonococci: correlation with virulence and serum resistance.

Encapsulated and non-encapsulated variants of one strain of gonococcus were compared for their capacity to produce infection in chambers implanted subcutaneously in mice, for their reactions with specific antibody and for their precipitation with wheat germ agglutinin. Only the encapsulated variant could infect implanted chambers. Specific rabbit antiserum raised against the non-encapsulated variant killed both variants. Saline extracts and lipopolysaccharide preparations of the encapsulated variant differed from those of the non-encapsulated one in their reactions with wheat germ agglutinin and antibody in diffusion and electrophoresis tests. Preparations from infective encapsulated gonococci reacted with wheat germ agglutinin while those from the non-encapsulated variant did not. Immunodiffusion tests showed that lipopolysaccharides from both variants share a common antigenic determinant, but saline extracts and lipopolysaccharides from encapsulated gonococci possess an additional determinant. The significance of these findings is discussed.

Animals↗
PubMed1978

Demonstration by light and electron microscopy of capsules on gonococci recently grown in vivo.

A study by light microscopy, using Leishman's stain alone or Leishman's stain followed by nigrosin, showed the presence of capsules on gonococci of two strains subcultured from subcutaneous chambers in guinea pigs. With the Alcian blue method of preparation for electron microscopy, gonococci of both strains recently grown in vivo showed densely stained capsules on some cells, while others in the same preparation showed only irregular masses of dense material on their surfaces with strands connecting adjacent bacteria. Treatment with antiserum, complement and conglutinin revealed irregular masses and strands of extracellular material with fixatives that did not contain Alcian blue.

Animals↗