Air evacuation under high-level biosafety containment: the aeromedical isolation team.
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Military contingency operations in tropical environments and potential use of biological weapons by adversaries may place troops at risk for potentially lethal contagious infections (e.g., viral hemorrhagic fevers, plague, and zoonotic poxvirus infections). Diagnosis and treatment of such infections would be expedited by evacuating a limited number of patients to a facility with containment laboratories. To safely evacuate such patients by military aircraft and minimize the risk for transmission to air crews, caregivers, and civilians, the U.S. Army Medical Research Institute of Infectious Diseases maintains an aeromedical isolation team. This rapid response team, which has worldwide airlift capability designed to evacuate and manage patients under high-level containment, also offers a portable containment laboratory, limited environmental decontamination, and specialized consultative expertise. This article also examines technical aspects of the team's equipment, training, capabilities, and deployments. (+info)
Bacterial toxin-antitoxin gene system as containment control in yeast cells.
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The potential of a bacterial toxin-antitoxin gene system for use in containment control in eukaryotes was explored. The Escherichia coli relE and relB genes were expressed in the yeast Saccharomyces cerevisiae. Expression of the relE gene was highly toxic to yeast cells. However, expression of the relB gene counteracted the effect of relE to some extent, suggesting that toxin-antitoxin interaction also occurs in S. cerevisiae. Thus, bacterial toxin-antitoxin gene systems also have potential applications in the control of cell proliferation in eukaryotic cells, especially in those industrial fermentation processes in which the escape of genetically modified cells would be considered highly risky. (+info)
Dual system to reinforce biological containment of recombinant bacteria designed for rhizoremediation.
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Active biological containment (ABC) systems have been designed to control at will the survival or death of a bacterial population. These systems are based on the use of a killing gene, e.g., a porin-inducing protein such as the one encoded by the Escherichia coli gef gene, and a regulatory circuit that controls expression of the killing gene in response to the presence or absence of environmental signals. An ABC system for recombinant microorganisms that degrade a model pollutant was designed on the basis of the Pseudomonas putida TOL plasmid meta-cleavage regulatory circuit. The system consists of a fusion of the Pm promoter to lacI, whose expression is controlled by XylS with 3-methylbenzoate, and a fusion of a synthetic P(lac) promoter to gef. In the presence of the model pollutant, bacterial cells survived and degraded the target compound, whereas in the absence of the aromatic carboxylic acid cell death was induced. The system had two main drawbacks: (i) the slow death of the bacterial cells in soil versus the fast killing rate in liquid cultures in laboratory assays, and (ii) the appearance of mutants, at a rate of about 10(-8) per cell and generation, that did not die after the pollutant had been exhausted. We reinforced the ABC system by including it in a Deltaasd P. putida background. A P. putida Deltaasd mutant is viable only in complex medium supplemented with diaminopimelic acid, methionine, lysine, and threonine. We constructed a P. putida Deltaasd strain, called MCR7, with a Pm::asd fusion in the host chromosome. This strain was viable in the presence of 3-methylbenzoate because synthesis of the essential metabolites was achieved through XylS-dependent induction. In the P. putida MCR7 strain, an ABC system (Pm::lacI, xylS, P(lac)::gef) was incorporated into the host chromosome to yield strain MCR8. The number of MCR8 mutants that escaped killing was below our detection limit (<10(-9) mutants per cell and generation). The MCR8 strain survived and colonized rhizosphere soil with 3-methylbenzoate at a level similar to that of the wild-type strain. However, it disappeared in less than 20 to 25 days in soils without the pollutant, whereas an asd(+), biologically contained counterpart such as P. putida CMC4 was still detectable in soils after 100 days. (+info)
Sequence analysis of cloned cDNA encoding part of an immunoglobulin heavy chain.
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The recombinant plasmid pH21-1 consists of mouse-derived complementary DNA (cDNA) in the E. coli plasmid pMB9. The mouse insertion has been completely sequenced, and encodes the CH3 domain and half the CH2 domain of the immunoglobulin gamma1 heavy chain. The predicted amino acid sequence differs at several positions from that previously published for this protein. The pattern of codon usage resembles that in some other eukaryotic messenger RNAs. A computer program has been used to predict the optimum secondary structure for the mRNA encoding the CH3 domain and the inter-domain junction. (+info)
Countering the posteradication threat of smallpox and polio.
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After eradication, there is a small but finite risk that smallpox and/or poliomyelitis viruses could accidentally escape from a laboratory or be released intentionally. The reintroduction of either virus into a highly susceptible population could develop into a serious catastrophe. To counter such an occurrence will require the use of vaccine, perhaps in substantial quantities. In the United States, new stocks of smallpox vaccine are being procured and arrangements are being made for a standby production facility. Similar provisions need to be considered for polio. To counter an epidemic of polio will require the use of the oral vaccine, which is presently the World Health Organization-recommended vaccine of choice for countries throughout the developing world. In these countries, its continued use is advised because of its ability to induce intestinal immunity, its ability to spread to other susceptible household members and to protect them, its ease of administration, and its low cost. (+info)
National laboratory inventory as part of global poliovirus containment--United States, June 2002.
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Since the initiation of the global poliomyelitis initiative in 1988 through 2001, the number of countries where polio is endemic decreased from 125 to 10, and the number of reported polio cases decreased >99%, from an estimated 350,000 to <1,000. The Global Commission for the Certification of the Eradication of Poliomyelitis, convened by the World Health Organization, will declare the world polio-free when all regions have documented the absence of wild poliovirus transmission for at least 3 consecutive years and when laboratories with wild poliovirus materials have implemented appropriate containment conditions. (+info)
Infection of mice with aerosolized Mycobacterium tuberculosis: use of a nose-only apparatus for delivery of low doses of inocula and design of an ultrasafe facility.
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Aerosolized delivery of virulent or hypervirulent Mycobacterium tuberculosis requires careful consideration of methodology and safety. To maximize safety, we installed a nose-only aerosol apparatus that can reproducibly deliver a low dose (<100 CFU per mouse) of M. tuberculosis in a carefully designed biohazard facility. (+info)
Measuring containment of viable infectious cell sorting in high-velocity cell sorters.
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BACKGROUND: With the advent of high-speed sorters, aerosols are a considerable safety concern when sorting viable infectious materials. We describe a four-part safety procedure for validating the containment. METHODS: This procedure includes aerosol containment, physical barriers, environmental controls, and personal protection. The Aerosol Management System (AMS) produces a negative pressure within the sort chamber, where aerosols are forced through a HEPA filter. Physical barriers include the manufacturer's standard plastic shield and panels. The flow cytometer was contained within a BSL-3 laboratory for maximum environmental control, and the operator was protected by a respiratory system. Containment was measured by using highly fluorescent Glo-Germ particles under the same conditions as the cell sort. RESULTS: Escaping aerosols were vacuumed for 10 min onto a glass slide and examined. With the AMS active and the cytometer producing the maximum aerosols possible, Glo-Germ particles remained within the sort chamber. Measurements taken directly outside the door averaged fewer than one particle per slide, and those taken at 2 ft away and on top of the sorter were completely negative. CONCLUSIONS: With this monitoring system in place, aerosols can be efficiently measured, thus reducing the risk to the operator while sorting viable infectious cells. (+info)