Bret K. Purcell

An alternative approach to combination vaccines: intradermal administration of isolated components for control of anthrax, botulism, plague and staphylococcal toxic shock

BackgroundCombination vaccines reduce the total number of injections required for each component administered separately and generally provide the same level of disease protection. Yet, physical, chemical, and biological interactions between vaccine components are often detrimental to vaccine safety or efficacy.MethodsAs a possible alternative to combination vaccines, we used specially designed microneedles to inject rhesus macaques with four separate recombinant protein vaccines for anthrax, botulism, plague and staphylococcal toxic shock next to each other just below the surface of the skin, thus avoiding potentially incompatible vaccine mixtures.ResultsThe intradermally-administered vaccines retained potent antibody responses and were well- tolerated by rhesus macaques. Based on tracking of the adjuvant, the vaccines were transported from the dermis to draining lymph nodes by antigen-presenting cells. Vaccinated primates were completely protected from an otherwise lethal aerosol challenge by Bacillus anthracis spores, botulinum neurotoxin A, or staphylococcal enterotoxin B.ConclusionOur results demonstrated that the physical separation of vaccines both in the syringe and at the site of administration did not adversely affect the biological activity of each component.The vaccination method we describe may be scalable to include a greater number of antigens, while avoiding the physical and chemical incompatibilities encountered by combining multiple vaccines together in one product.

A short course of antibiotic treatment is effective in preventing death from experimental inhalational anthrax after discontinuing antibiotics.

BACKGROUND Postexposure prophylaxis of inhalational anthrax requires prolonged antibiotic therapy or antibiotics and vaccination. The duration of treatment for established anthrax is controversial, because retained spores may germinate and cause disease after antibiotics are discontinued. Using rhesus macaques, we determined whether a short course of antibiotic treatment, as opposed to prophylaxis, could effectively treat inhalational anthrax and prevent disease caused by the germination of spores after discontinuation of antibiotics. METHODS Two groups of 10 rhesus macaques were exposed to an aerosol dose of Bacillus anthracis spores. Animals in group 1 received ciprofloxacin prophylaxis beginning 1-2 h after exposure. Those in group 2 began receiving ciprofloxacin after becoming bacteremic, and treatment was continued for 10 days. When each group 2 animal completed 10 days of therapy, the prophylactic antibiotic was discontinued in the paired group 1 animal. RESULTS In group 1 (prophylaxis), no deaths occurred during antibiotic treatment, but only 2 (20%) of 10 animals survived after antibiotics were discontinued. In contrast, in group 2 (treatment), 3 deaths occurred during antibiotic treatment, but all 7 animals (100%) alive after 10 days of therapy survived when antibiotics were discontinued. CONCLUSIONS In the treatment of inhalational anthrax, the prolonged course of antibiotics required to achieve prophylaxis may not be necessary to prevent anthrax that results from the germination of retained spores after the discontinuation of antibiotics.

Lipid modification of the 15 kiloDalton major membrane immunogen of Treponema pallidum

The 15 kiloDalton major membrane immunogen was included among the Treponema pallidum polypeptides selectively labelled with [3H]‐palmitate. The cloned gene for this immunogen, tpp15, encoded a signal peptide of 17 amino acids, a consensus signal peptidase II cleavage site, and a mature protein of 124 amino acids (13967 Daltons). As predicted by the DNA sequence, the recombinant 15 kiloDalton immunogen labelled selectively with [3H]‐palmitate, and globo‐mycin inhibited processing of the precursor to the mature polypeptide. While the native and recombinant immunogens are amphiphilic, the 15 kiloDalton immunogen synthesized in a cell‐free system was hydrophilic. The covalent attachment of fatty acids appears to be responsible for the amphilicity of the immunogen and its membrane attachment.

In Vitro Antibiotic Susceptibilities of Yersinia pestis Determined by Broth Microdilution following CLSI Methods

ABSTRACT In vitro susceptibilities to 45 antibiotics were determined for 30 genetically and geographically diverse strains of Yersinia pestis by the broth microdilution method at two temperatures, 28°C and 35°C, following Clinical and Laboratory Standards Institute (CLSI) methods. The Y. pestis strains demonstrated susceptibility to aminoglycosides, quinolones, tetracyclines, β-lactams, cephalosporins, and carbapenems. Only a 1-well shift was observed for the majority of antibiotics between the two temperatures. Establishing and comparing antibiotic susceptibilities of a diverse but specific set of Y. pestis strains by standardized methods and establishing population ranges and MIC50 and MIC90 values provide reference information for assessing new antibiotic agents and also provide a baseline for use in monitoring any future emergence of resistance.

In Vitro Antibiotic Susceptibilities of Francisella tularensis Determined by Broth Microdilution following CLSI Methods

ABSTRACT In vitro susceptibilities for 47 antibiotics were determined in 30 genetic diverse strains of Francisella tularensis by the broth microdilution method following Clinical and Laboratory Standards Institute (CLSI) methods. The F. tularensis strains demonstrated susceptibility to aminoglycosides, fluoroquinolones, and tetracyclines. There was a distinct difference in macrolide susceptibilities between A and B type strains, as has been noted previously. The establishment and comparison of antibiotic susceptibilities of a diverse but specific set of F. tularensis strains by standardized methods and the establishment of population ranges and MIC50/90 values provide reference information for assessing new antibiotic agents and a baseline to monitor any future emergence of resistance, whether natural or intentional.