Live attenuated Francisella novicida vaccine protects against Francisella tularensis pulmonary challenge in rats and non-human primates.

Francisella tularensis causes the disease tularemia. Human pulmonary exposure to the most virulent form, F. tularensis subsp. tularensis (Ftt), leads to high morbidity and mortality, resulting in this bacterium being classified as a potential biothreat agent. However, a closely-related species, F. novicida, is avirulent in healthy humans. No tularemia vaccine is currently approved for human use. We demonstrate that a single dose vaccine of a live attenuated F. novicida strain (Fn iglD) protects against subsequent pulmonary challenge with Ftt using two different animal models, Fischer 344 rats and cynomolgus macaques (NHP). The Fn iglD vaccine showed protective efficacy in rats, as did a Ftt iglD vaccine, suggesting no disadvantage to utilizing the low human virulent Francisella species to induce protective immunity. Comparison of specific antibody profiles in vaccinated rat and NHP sera by proteome array identified a core set of immunodominant antigens in vaccinated animals. This is the first report of a defined live attenuated vaccine that demonstrates efficacy against pulmonary tularemia in a NHP, and indicates that the low human virulence F. novicida functions as an effective tularemia vaccine platform.

Plazomicin is effective in a non-human primate pneumonic plague model.

The efficacy of plazomicin for pneumonic plague was evaluated in a non-human primate model. African Green monkeys challenged with a lethal aerosol of Yersinia pestis [median (range) of 98 (15-331) LD50s] received placebo (n=12) or 'humanized' dose regimens (6.25, 12.5 or 25mg/kg every 24h) of plazomicin (n=52) after the onset of fever for a duration of 5 or 10days. All animals treated with placebo died, while 36 plazomicin-treated animals survived through study end. The majority (33/36) were either in the 10-day (high-/mid-/low-dose) or 5-day high-dose groups. The findings suggest an exposure range of plazomicin for treatment of pneumonic/bacteremic Y. pestis infection in humans.

Lethal factor, but not edema factor, is required to cause fatal anthrax in cynomolgus macaques after pulmonary spore challenge.

Inhalational anthrax is caused by inhalation of Bacillus anthracis spores. The ability of B. anthracis to cause anthrax is attributed to the plasmid-encoded A/B-type toxins, edema toxin (edema factor and protective antigen) and lethal toxin (lethal factor and protective antigen), and a poly-d-glutamic acid capsule. To better understand the contribution of these toxins to the disease pathophysiology in vivo, we used B. anthracis Ames strain and isogenic toxin deletion mutants derived from the Ames strain to examine the role of lethal toxin and edema toxin after pulmonary spore challenge of cynomolgus macaques. Lethal toxin, but not edema toxin, was required to induce sustained bacteremia and death after pulmonary challenge with spores delivered via bronchoscopy. After intravenous challenge with bacilli to model the systemic phase of infection, lethal toxin contributed to bacterial proliferation and subsequent host death to a greater extent than edema toxin. Deletion of protective antigen resulted in greater loss of virulence after intravenous challenge with bacilli than deletion of lethal toxin or edema toxin alone. These findings are consistent with the ability of anti-protective antigen antibodies to prevent anthrax and suggest that lethal factor is the dominant toxin that contributes to the escape of significant numbers of bacilli from the thoracic cavity to cause anthrax after inhalation challenge with spores.

Performance evaluation of Puritan® universal transport system (UniTranz-RT™) for preservation and transport of clinical viruses.

The ability of a non-propagating microbial transport medium to maintain the viability of clinically relevant viruses was compared to a similar commercial medium to establish performance equivalence. Two dilutions of stock of test viruses, namely adenovirus (AdV), cytomegalovirus (CMV), echovirus Type 30 (EV), herpes simplex virus (HSV) types 1 and 2, influenza A, parainfluenza 3 (PIV), respiratory syncytial virus (RSV), and varicella zoster virus (VZV), were spiked into Puritan® Medical Products Company Universal Transport System (UniTranz-RT™) and BD(TM) Universal Viral Transport System (UVT) and incubated at 4 °C and room temperature (RT) for up to 72 hr. Post incubation assessment of recovery of AdV, EV, HSV-2, PIV, and VZV from UniTranz-RT™ and UVT using shell vial assays followed by immunofluorescence staining demonstrated statistically significant differences between both transport media. In general, significantly higher recoveries of AdV, EV, and VZV were found from UniTranz-RT™ than UVT whereas HSV-2 and PIV were recovered better from UVT than UniTranz-RT™, under specific test conditions. The recovery of HSV-1, influenza A, PIV, and RSV showed no significant differences between transport media. Sulforhodamine B-based assay analysis of UniTranz-RT™ lots prior to and at expiration exhibited no cytotoxicity. The overall results of the study validate the full performance of UniTranz-RT™ as a viral transport medium and establish its effectiveness on par with the UVT.

Performance evaluation of two microbial transport media designed for preservation and transport of Chlamydiae, Mycoplasma and Ureaplasma.

The ability of a non-propagating transport device (test device) to maintain the viability of clinically relevant bacteria was compared with a similar commercial device (predicate device) to establish performance equivalence. Test bacteria, namely Chlamydia trachomatis, Chlamydia pneumoniae, Mycoplasma hominis, Mycoplasma pneumoniae and Ureaplasma urealyticum, were inoculated into the test [Puritan Medical Products Universal Transport System (UniTranz-RT(TM))] and predicate (BD Universal Viral Transport System) devices, and incubated at 4 °C and room temperature for up to 72 h. Bacterial viability was assessed at selected time points post-incubation using shell vial assays followed by immunofluorescence staining (for Chlamydia) or by standard culture techniques (for Mycoplasma and Ureaplasma). Results indicated that the Chlamydia strains were equally stable in both test and predicate devices through 72 h storage, at both test temperatures. Quantifiable levels of Mycoplasma and Ureaplasma were recovered from the test and predicate devices throughout the storage period. Low-temperature storage improved bacterial viability when compared with room temperature storage. In addition, the predicate device demonstrated slightly improved performance versus the test device in the context of Mycoplasma and Ureaplasma following 72 h storage. The overall results of the study confirmed the full performance of UniTranz-RT(TM) as a microbial transport medium and established equal performance with the predicate device.

Inhalational anthrax (Ames aerosol) in naïve and vaccinated New Zealand rabbits: characterizing the spread of bacteria from lung deposition to bacteremia.

There is a need to better understand inhalational anthrax in relevant animal models. This understanding could aid risk assessment, help define therapeutic windows, and provide a better understanding of disease. The aim here was to characterize and quantify bacterial deposition and dissemination in rabbits following exposure to single high aerosol dose (> 100 LD(50)) of Bacillus anthracis (Ames) spores immediately following exposure through 36 h. The primary goal of collecting the data was to support investigators in developing computational models of inhalational anthrax disease. Rabbits were vaccinated prior to exposure with the human vaccine (Anthrax Vaccine Adsorbed, AVA) or were sham-vaccinated, and were then exposed in pairs (one sham and one AVA) so disease kinetics could be characterized in equally-dosed hosts where one group is fully protected and is able to clear the infection (AVA-vaccinated), while the other is susceptible to disease, in which case the bacteria are able to escape containment and replicate uncontrolled (sham-vaccinated rabbits). Between 4-5% of the presented aerosol dose was retained in the lung of sham- and AVA-vaccinated rabbits as measured by dilution plate analysis of homogenized lung tissue or bronchoalveolar lavage (BAL) fluid. After 6 and 36 h, >80% and >96%, respectively, of the deposited spores were no longer detected in BAL, with no detectable difference between sham- or AVA-vaccinated rabbits. Thereafter, differences between the two groups became noticeable. In sham-vaccinated rabbits the bacteria were detected in the tracheobronchial lymph nodes (TBLN) 12 h post-exposure and in the circulation at 24 h, a time point which was also associated with dramatic increases in vegetative CFU in the lung tissue of some animals. In all sham-vaccinated rabbits, bacteria increased in both TBLN and blood through 36 h at which point in time some rabbits succumbed to disease. In contrast, AVA-vaccinated rabbits showed small numbers of CFU in TBLN between 24 and 36 h post-exposure with small numbers of bacteria in the circulation only at 24 h post-exposure. These results characterize and quantify disease progression in naïve rabbits following aerosol administration of Ames spores which may be useful in a number of different research applications, including developing quantitative models of infection for use in human inhalational anthrax risk assessment.