In December 1993 and May 1996 FDA issued letters advising that bovine derived materials from animals born in or residing in countries where BSE had occurred should not be used to manufacture FDA-regulated products intended for administration to humans. In a 1991 letter to manufacturers CBER expressed concern about bovine sourced material. The Center for Biologics Evaluation and Research (CBER) is responsible for regulation of biologic products, including vaccines. However, FDA wants to minimize any chance that the BSE agent could be introduced into biologic products during manufacture. It is believed that variant CJD was acquired from eating food products containing the BSE agent. What measures have the FDA taken to ensure that people are not exposed to the BSE agent in vaccines? Questions about FDA Preventative Measures Also the production processes used to prepare bovine-derived materials (such as heat sterilization and chemical treatment) may reduce or remove infectivity. However, the slaughtering and butchering methods used to obtain tissues and prepare materials can affect the amount of infectivity that may be present. Some tissues, such as skeletal muscle and milk, have never been shown to have any infectivity. It is generally believed that the highest amounts of infectivity are found in the brain and spinal cord from animals in the final stages of clinical disease. Scientists have found that different bovine tissues contain different amounts of the BSE agent. Many difficult to grow microorganisms and the cells that are used to propagate viruses require the addition of serum from blood to the growth media.ĭo all bovine materials have the same risk of transmitting the BSE agent? Cow skeletal muscle is used to prepare broths used in certain complex media. Gelatin and some amino acids come from cow bones. Cow tallow derivatives used in vaccine manufacture include glycerol. Cow milk is a source of amino acids, and sugars such as galactose. Animal-derived products used in vaccine manufacture can include amino acids, glycerol, detergents, gelatin, enzymes and blood. Cow components are often used simply because cows are very large animals, commonly used for food, and thus much material is available. Microorganisms for vaccine manufacture are grown under controlled conditions in media which provide the nutrients necessary for growth. Which bovine derived materials are used in vaccine manufacture? Viral vaccines are produced in living cells, which, similarly, require the addition of complex growth media components, such as fetal calf serum. Although synthetic media have been developed for growth of many medically important microorganisms, some still require additional nutrients which are easily provided by animal-derived products such as serum and blood. The early bacteriologists tried to mimic as closely as possible the environment in an infected person's tissues by using solutions containing sugars, salts, and various meat extracts to make "growth media." These kinds of conditions were quite successful in growing bacteria and then viruses in the lab, because these media supplied the many necessary nutrients. In the late 19th century, microbiologists began to grow bacteria in the laboratory. Vaccines contain either killed or weakened forms of disease-causing bacteria or viruses, or components of these that stimulate a response by the body's immune system, which then protects against the development of disease. Why are animal products used in the manufacture of vaccines? Questions about Animal Products and Vaccine Manufacturing Questions about FDA Preventative Measures.Questions about Animal Products and Vaccine Manufacturing.
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