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lunes, 28 de noviembre de 2016

Preparation of viral samples within biocontainment for ultrastructural analysis

Transmission electron microscopy can be used to observe the ultrastructure of viruses and other microbial pathogens with nanometer resolution. In a transmission electron microscope (TEM), the image is created by passing an electron beam through a specimen with contrast generated by electron scattering from dense elements in the specimen. Viruses do not normally contain dense elements, so a negative stain that places dense heavy metal salts around the sample is added to create a dark border. To prepare a virus sample for a negative stain transmission electron microscopy, a virus suspension is applied to a TEM grid specimen support, which is a 3mm diameter fragile specimen screen coated with a few nanometers of plastic film. Then, deionized (dI) water rinses and a negative stain solution are applied to the grid. All infectious viruses must be handled in a biosafety cabinet (BSC) and many require a biocontainment laboratory environment. Staining viruses in biosafety levels (BSL) 3 and 4 is especially challenging because the support grids are small, fragile, and easily moved by air currents. In this study we evaluated a new device for negative staining viruses called mPrep/g capsule. It is a capsule that holds up to two TEM grids during all processing steps and for storage after staining is complete. This study reports that the mPrep/g capsule method is valid and effective to negative stain virus specimens, especially in high containment laboratory environments.

REFERENCE:
Monninger MK, et al. Preparation of viral samples within biocontainment for ultrastructural analysis: Utilization of an innovative processing capsule for negative staining. J Virol Methods. 2016 Dec;238:70-76. doi: 10.1016/j.jviromet.2016.10.005. PubMed PMID: 27751950.
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martes, 22 de noviembre de 2016

#VIDEO: Safety Precautions and Operating Procedures in an (A)BSL-4 Laboratory

Biosafety level 4 (BSL-4) suit laboratories are specifically designed to study high-consequence pathogens for which neither infection prophylaxes nor treatment options exist. The hallmarks of these laboratories are: custom-designed airtight doors, dedicated supply and exhaust airflow systems, a negative-pressure environment, and mandatory use of positive-pressure (“space”) suits. The risk for laboratory specialists working with highly pathogenic agents is minimized through rigorous training and adherence to stringent safety protocols and standard operating procedures. Researchers perform the majority of their work in BSL-2 laboratories and switch to BSL-4 suit laboratories when work with a high-consequence pathogen is required. Collaborators and scientists considering BSL-4 projects should be aware of the challenges associated with BSL-4 research both in terms of experimental technical limitations in BSL-4 laboratory space and the increased duration of such experiments. Tasks such as entering and exiting the BSL-4 suit laboratories are considerably more complex and time-consuming compared to BSL-2 and BSL-3 laboratories. The focus of this particular article is to address basic biosafety concerns and describe the entrance and exit procedures for the BSL-4 laboratory at the NIH/NIAID Integrated Research Facility at Fort Detrick. Such procedures include checking external systems that support the BSL-4 laboratory, and inspecting and donning positive-pressure suits, entering the laboratory, moving through air pressure-resistant doors, and connecting to air-supply hoses. We will also discuss moving within and exiting the BSL-4 suit laboratories, including using the chemical shower and removing and storing positive-pressure suits.

REFERENCE:
Janosko, Krisztina et al. “Safety Precautions and Operating Procedures in an (A)BSL-4 Laboratory: 1. Biosafety Level 4 Suit Laboratory Suite Entry and Exit Procedures.” Journal of Visualized Experiments : JoVE 116 (2016): 52317. PMC. Web. 17 Nov. 2016.
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lunes, 14 de noviembre de 2016

Containment of Arthropod Disease Vectors

Arthropods
Effective containment of arthropod vectors of infectious diseases is necessary to prevent transmission of pathogens by released, infected vectors and to prevent vectors that escape from establishing populations that subsequently contribute to increased disease. Although rare, past releases illustrate what can go wrong and justify the need for guidelines that minimize risks. An overview of recommendations for insectary facilities, practices, and equipment is provided, and features of four recently published and increasingly rigorous arthropod containment levels (ACLs 1-4) are summarized. ACL-1 is appropriate for research that constitutes the lowest risk level, including uninfected arthropods or vectors that are infected with micro-organisms that do not cause disease in humans, domestic animals, or wildlife. ACL-2 is appropriate for indigenous and exotic arthropods that represent a moderate risk, including vectors infected or suspected of being infected with biosafety level (BSL)-2 infectious agents and arthropods that have been genetically modified in ways that do not significantly affect their fecundity, survival, host preference, or vector competence. ACL-3 is recommended for arthropods that are or may be infected with BSL-3 infectious agents. ACL-3 places greater emphasis on pathogen containment and more restricted access to the insectary than ACL-2. ACL-4 is intended for arthropods that are infected with the most dangerous BSL-4 infectious agents, which can cause life-threatening illness by aerosol or arthropod bite. Adherence to these guidelines will result in laboratory-based arthropod vector research that minimizes risks and results in important new contributions to applied and basic science.

REFERENCE:
Scott TW. Containment of arthropod disease vectors. ILAR J. 2005;46(1):53-61. Review.

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lunes, 7 de noviembre de 2016

Communicable Diseases and Outbreak Control

Infectious disease during an emergency condition can raise the death rate 60 times in comparison to other causes including trauma. An epidemic, or outbreak, can occur when several aspects of the agent (pathogen), population (hosts), and the environment create an ideal situation for spread. Overcrowding, poor regional design and hygiene due to poverty, dirty drinking water, rapid climate changes, and natural disasters, can lead to conditions that allow easier transmission of disease. Once it has been established that an emergency condition exists, there must be a prompt and thorough response for communicable disease control. A camp should be created, and the disease managed rapidly. The overall goals are rapid assessment, prevention, surveillance, outbreak control, and disease management.
REFERENCE:
AMELI, Jonathan. “Communicable Diseases and Outbreak Control.” Turkish Journal of Emergency Medicine 15.Suppl 1 (2015): 20–26. PMC.

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