Biomedical subjects

Wolfgang Beyer

Publications and source records attributed to Wolfgang Beyer.

7 recordsLinked to original sources

PubMed2005

DNA vaccination against anthrax in mice-combination of anti-spore and anti-toxin components.

The predominant antigen in human anthrax vaccines is the protective antigen (PA) of Bacillus anthracis. To address the question whether immune responses against B. anthracis spores can improve the protectivity of a PA-based DNA vaccine against anthrax, we designed a eucaryotic expression plasmid encoding the exosporium antigen BclA, which is a collagen-like surface protein. This plasmid, pSecTag BclA, carries a secretion signal for the recombinant antigen. Using NMRI mice we compared the effects of immunisation with a combination of PA- and BclA-encoding plasmid DNA, to immunisations with either PA- or BclA-encoding pDNA. After three immunisations the mice were infected with 25 x LD(50) of B. anthracis Ames spores. The plasmid pSecTag BclA, induced high BclA-specific antibody responses. Vaccination with a combination of PA- and BclA-encoding pDNA led to significantly better survival than immunisation with only PA- or only BclA-encoding plasmids.

Animals↗

PubMed2005

Comparison of the immunological memory after DNA vaccination and protein vaccination against anthrax in sheep.

Currently available live spore vaccines against anthrax in animals have many drawbacks, one of which is their presumed inability to induce a long lasting immunity. In the present study we compared the immunological memory after a protein vaccination with DNA vaccinations in sheep. The antigen used was the protective antigen (PA83) of Bacillus anthracis. Sheep were vaccinated three times with either PA83 plus alhydrogel, or with one of four different plasmid DNA formulations, which all encoded either the full-length PA83 or its domain 4. Two pDNA formulations included Vaxfectin adjuvant, the other two were injected in PBS without adjuvant. Initially, the antibody titres of protein vaccinated sheep were significantly higher than the titres of pDNA vaccinated sheep. After 5 months, however, the antibody titres of protein vaccinated sheep had dropped remarkably, while the titres of all four pDNA vaccinated groups were either stable or had increased. Humoral responses of sheep immunised with pDNA formulated with Vaxfectin adjuvant were higher than the responses of the corresponding groups that received pDNA in PBS only.

Animals↗

PubMed2005

Growth characteristics of Bacillus anthracis compared to other Bacillus spp. on the selective nutrient media Anthrax Blood Agar and Cereus Ident Agar.

Anthrax Blood Agar (ABA) and Cereus Ident Agar (CEI) were evaluated as selective growth media for the isolation of Bacillus anthracis using 92 B. anthracis and 132 other Bacillus strains from 30 species. The positive predictive values for the identification of B. anthracis on ABA, CEI, and the combination of both were 72%, 71%, and 90%, respectively. Thus, less than 10% of all species were misidentified using both nutrient media. Species which might be misidentified as B. anthracis were B. cereus, B. mycoides, and B. thuringiensis. Particularly, 30% of B. weihenstephanensis strains were misidentified as B. anthracis.

Agar↗

PubMed2004

Oligonucleotide microarray for identification of Bacillus anthracis based on intergenic transcribed spacers in ribosomal DNA.

We developed a DNA microarray for identification of Bacillus anthracis and other phylogenetic groupings within the "Bacillus cereus group". Nucleotide sequences of 16S-23S ribosomal DNA internal transcribed spacers containing genes for tRNA(Ile) from 52 B. anthracis strains were found to be identical to sequences from seven strains published previously and different from all other bacteria. When 42 oligonucleotide probes targeting polymorphic sites were immobilized on glass slides and hybridized to fluorescently labeled PCR amplification products, one or more mismatches could be discriminated in all but one cases. Hence, hybridization events were highly specific and identification of B. anthracis was straightforward.

Bacillus anthracis↗

PubMed2004

Protection of mice against challenge with Bacillus anthracis STI spores after DNA vaccination.

Immune responses against the protective antigen (PA) of Bacillus anthracis are known to confer immunity against anthrax. We evaluated the efficacy of genetic vaccination with plasmid vectors encoding PA, in protecting mice from a lethal challenge with B. anthracis STI spores. BALB/c and A/J mice were immunized via gene gun inoculation, using eukaryotic expression vectors with different cellular targeting signals for the encoded antigen. The vector pSecTag PA83, encoding the full-length PA protein, has a signal sequence for secretion of the expressed protein. The plasmids pCMV/ER PA83 and pCMV/ER PA63, encoding the full-length and the physiologically active form of PA, respectively, target and retain the expressed antigen in the endoplasmic reticulum of transfected cells. All three plasmids induced PA-specific humoral immune responses, predominantly IgG1 antibodies, in mice. Spleen cells collected from plasmid-vaccinated BALB/c mice produced PA-specific interleukin-4, interleukin-5, and interferon-gamma in vitro. Vaccination with either pSecTag PA83 or pCMV/ER PA83 showed significant protection of A/J mice against infection with B. anthracis STI spores.

Animals↗

PubMed2003

Salmonella enterica serovar typhimurium expressing a chromosomally integrated copy of the Bacillus anthracis protective antigen gene protects mice against an anthrax spore challenge.

Protective immunity against infection with Bacillus anthracis is almost entirely based on a response to the protective antigen (PA), the binding moiety for the two other toxin components. We cloned the PA gene into an auxotrophic mutant of Salmonella enterica serovar Typhimurium as a fusion with the signal sequence of the hemolysin (Hly) A gene of Escherichia coli to allow the export of PA via the Hly export system. To stabilize the export cassette, it was also integrated into the chromosome of the live Salmonella carrier. When S. enterica serovar Typhimurium with the chromosomally integrated PA gene was given intravenously to A/J mice, they developed high levels of antibody to PA. These mice were protected against intraperitoneal challenge with 100 or 1,000 50% lethal doses of B. anthracis strain STI. This work contributes to the development of a Salmonella-based orally delivered anthrax vaccine.

Animals↗

PubMedDate not supplied

[Vaccination strategies for anthrax prevention].

Apart from live spore vaccines with a certain amount of residual virulence for various animal species, there are two acellular protein vaccines for immunoprophylaxis against anthrax in humans. For ethical reasons there are no experimental data available on the efficacy and duration of the immunity they induce in men. Their efficacy was evaluated in laboratory animals, mainly rabbits and rhesus monkeys. Furthermore, it is well known that these vaccines elicit only partial protection in guinea pigs and almost no protection in mice against a challenge with fully virulent spores of Bacillus (B.) anthracis. Other disadvantages are the high amount of boosters necessary to elicit and to maintain a protective immune response, the variability in the composition of bacterial culture supernatants used for production, and the appearance of clinically relevant side effects. Therefore, there is ongoing work worldwide to improve the existing vaccines by substitution with recombinant antigens and to develop new vaccines on the basis of recombinant bacterial or viral live vectors, DNA-vectors, and by addition of new adjuvants. Special attention is given to supplementing the existing toxoid-vaccines with an anti-bacterial component.

Animals↗