The fact that optimal in vitro growth of Haemophilus ducreyi occurs at 33 degrees C prompted evaluation of the effect of temperature on the ability of this organism to produce skin lesions in rabbits after intradermal inoculation. Animals housed at a reduced ambient temperature (15-17 degrees C) consistently developed necrotic lesions when injected intradermally with 10(5) cfu of H. ducreyi; this inoculum did not produce necrotic lesions in animals housed at normal room temperature (23-25 degrees C). Lesion production in this new model was dependent on both viability of the H. ducreyi inoculum and replication of these organisms after intradermal injection. Histopathologic examination of the lesions revealed that H. ducreyi infection of the rabbit dermis evolves from an acute inflammatory reaction to abscess formation. Evaluation of three additional strains of H. ducreyi in this model confirmed that lesion formation was not bacterial strain-dependent. This new temperature-dependent rabbit model for productive H. ducreyi infection will facilitate investigation of the molecular pathogenesis of chancroid.

The nucleotide sequences of the genes encoding the subunits of Klebsiella pneumoniae and Salmonella typhimurium type 1 fimbriae were determined. Comparison of the predicted amino acid sequences of the two subunits revealed domains in which the sequences were highly conserved. Both gene products possessed signal peptides, a fact consistent with the transport of the fimbrial subunit across the membrane, but these regions showed no amino acid homology between the two proteins. The predicted N-terminal amino acid sequences of the processed fimbrial subunits were in good agreement with those obtained by purification of the fimbrial subunits.

A murine monoclonal antibody specific for a 17-kDa major membrane immunogen of Treponema paUlidum was used to select recombinant Escherichia coli clones expressing the molecule from a T. paUidum genomic library. Sequence analysis of the structural gene for the immunogen (designated tppl 7) revealed a 468-bp open reading frame encoding a polypeptide of 156 amino acids with a calculated molecular mass of 16,441 Da. The deduced amino acid sequence included a putative leader peptide terminated by a consensus tetrapeptide for the modification and processing of prokaryotic lipoproteins. Immunoprecipitation of the cloned immunogen radiolabeled with [3Hlpalmitate confirmed that it was a lipoprotein. The amino acid sequence also predicted that the mature protein contains four cysteine residues in addition to the lipid-modified cysteine of the N terminus. The existence of disulfide-bonded multimeric forms of the native immunogen was demonstrated by immunoblotting T. paUlidum solubilized in the presence and absence of 2-mercaptoethanol. Triton X-114 phase partitioning of a nonlipidated form of the 17-kDa immunogen cleaved from a glutathione S-transferase fusion protein demonstrated that lipid modification is responsible for the immunogen's hydrophobic character. The same nonlipidated form of the immunogen also was used to demonstrate that lipid modification is essential for the molecule's ability to stimulate production of tumor necrosis factor alpha by murine macrophages. We conclude that covalently attached fatty acids not only anchor T. paUidum lipoproteins to spirochetal membranes but also confer upon these molecules the ability to activate immune effector cells.

Prevention of inhalational anthrax after Bacillus anthracis spore exposure requires a prolonged course of antibiotic prophylaxis. In response to the 2001 anthrax attack in the United States, Ϸ10,000 people were offered 60 days of antibiotic prophylaxis to prevent inhalational anthrax, but adherence to this regimen was poor. We sought to determine whether a short course of antibiotic prophylaxis after exposure could protect non-human primates from a high-dose spore challenge if vaccination was combined with antibiotics. Two groups of 10 rhesus macaques were exposed to Ϸ1,600 LD 50 of spores by aerosol. Both groups were given ciprofloxacin by orogastric tube twice daily for 14 days, beginning 1-2 h after exposure. One group also received three doses of the licensed human anthrax vaccine (anthrax vaccine adsorbed) after exposure. In the ciprofloxacin-only group, four of nine monkeys (44%) survived the challenge. In contrast, all 10 monkeys that received 14 days of antibiotic plus anthrax vaccine adsorbed survived (P ‫؍‬ 0.011). Thus postexposure vaccination enhanced the protection afforded by 14 days of antibiotic prophylaxis alone and completely protected animals against inhalational anthrax. These data provide evidence that postexposure vaccination can shorten the duration of antibiotic prophylaxis required to protect against inhalational anthrax and may impact public health management of a bioterrorism event.Bacillus anthracis ͉ treatment ͉ vaccine B acillus anthracis infection in humans occurs as cutaneous, gastrointestinal, or inhalational anthrax depending upon the route of exposure. Cutaneous anthrax is rarely fatal and can be effectively treated with antibiotics. Inhalational anthrax, the form likely to occur after a bioterrorist attack, on the other hand, is difficult to diagnose early, and despite antibiotic therapy, has a high fatality rate. Anthrax is rare in industrialized countries, and vaccination with anthrax vaccine adsorbed (AVA) is confined to those who could be potentially exposed to anthrax, such as veterinary workers, woolen mill employees, and laboratory workers (1). Military personnel in the United States are also vaccinated due to the potential threat of B. anthracis being used as a bioweapon.Past experiments have shown that the rhesus macaque is the animal model that most closely mimics inhalational anthrax in humans (2). In both humans and macaques, inhalational anthrax begins with the deposition of 1-to 5-m spores in the alveolar spaces, where spores are thought to be ingested by alveolar phagocytic cells. Some spores survive inside the phagocyte and are transported to the draining pulmonary and mediastinal lymph nodes where germination occurs. Although most spores probably germinate within a few days after inhalation, germination is not synchronous (3). Some spores remain dormant and do not germinate for prolonged periods (4, 5). It is the delayed germination of retained spores into vegetative bacilli that necessitates the prolonged use of prophylactic antibiotics after an inhalational ...

Nine rhesus macaques were implanted with multisensor telemetry devices and internal jugular vein catheters before being infected with Zaire ebolavirus. All animals developed viremia, fever, a hemorrhagic rash, and typical changes of Ebola hemorrhagic fever in clinical laboratory tests. Three macaques unexpectedly survived this usually lethal disease, making it possible to compare physiological parameters in lethally challenged animals and survivors. After the onset of fever, lethal illness was characterized by a decline in mean arterial blood pressure, an increase in pulse and respiratory rate, lactic acidosis, and renal failure. Survivors showed less pronounced change in these parameters. Four macaques were randomized to receive supplemental volumes of intravenous normal saline when they became hypotensive. Although those animals had less severe renal compromise, no apparent survival benefit was observed. This is the first report of continuous physiologic monitoring in filovirus-infected nonhuman primates and the first to attempt cardiovascular support with intravenous fluids.

Bacillus anthracis lethal toxin (LT) was characterized in plasma from infected

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 (13,967 Daltons). As predicted by the DNA sequence, the recombinant 15 kiloDalton immunogen labelled selectively with [3H]-palmitate, and globomycin 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 amphiphilicity of the immunogen and its membrane attachment.

Abstract. Tularemia, caused by Francisella tularensis, is a sporadic zoonotic disease with the potential to be an agent of biowarfare or bioterrorism. We describe here the gross, histologic, immunohistochemical, and ultrastructural findings in a group of 5 African green monkeys (AGMs) that received an average inhaled dose of 729 colony-forming units of F. tularensis and died or were euthanatized between days 7 and 11 post infection. Clinical changes were evident by 48 hours post infection, and key physiologic abnormalities included increases in body temperature, heart rate, peak cardiac pressure, and mean blood pressure. Prominent gross changes in all cases included numerous pinpoint to 1-cm, well-demarcated, necrotic foci present consistently in the lungs, mediastinal lymph nodes, and spleen but also seen in the heart, mediastinum, diaphragm, liver, urinary bladder, urethra, and mesentery. The lungs, mediastinal lymph nodes, and spleen were most severely affected, with as much as 50% of the tissue replaced by necrotic foci. Histologic changes in all tissues consisted of welldelineated foci of necrosis and neutrophilic and histiocytic inflammation, with varying amounts of hemorrhage, edema, fibrin, and vasculitis. Some lesions were immature pyogranulomas. Strong immunoreactivity was identified primarily within macrophages. Ultrastructurally, bacteria were present within cytoplasmic vacuoles of alveolar macrophages, many of which were degenerate. In summary, AGMs infected with F. tularensis by aerosol develop lethal multisystemic disease that particularly targets the lungs and lymphoid tissues. Thus, AGMs should serve as a suitable and reliable animal model for further studies of tularemia.