Live attenuated organisms

Live Attenuated Organisms. Live attenuated bacteria and viruses have been used not only as vaccines but also as a delivery system that elicits humoral, mucosal, and cellular immune responses against exogenous antigens. Since the success with live attenuated oral vaccines against tuberculosis and polio more than 3 decades ago, a number of live attenuated microorganisms have been used as antigen-delivery systems. Live vaccines are relatively easy and cheap to manufacture, because they do not require purification of... 

Vaccination to induce an adaptive immune response is expected for a broad range of infectious diseases and cancers. Traditional vaccines are mainly composed of live attenuated viruses, whole inactivated pathogens, or inactivated bacterial toxins. In general, these approaches have been successful for developing vaccines that can induce an immune response based on antigen-specific antibody and cytotoxic T lymphocyte (CTL) responses, which kill host cells infected with intracellular organisms (Fig. 1) [1,2], One of the most important current issues in vaccinology is the need for new adjuvants (immunostimulants) and delivery systems. Many of the vaccines currently in development are based on purified subunits, recombinant... 

There are two classical strategies for vaccination. One involves vaccination with either killed pathogenic organisms or subunits of the pathogenic organism. The other utilizes live attenuated viruses or bacteria that do not cause disease but have been derived from the pathogenic parent organism. 

Inherently safer than the live attenuated organism as replication or mutation to a more pathogenic form cannot occur... 

The method allows genes that confer pathogenicity or virulence to be excluded Inherently safer than the live attenuated organism as replication or mutation to a more pathogenic form cannot occur Can be prepared and purified easily More thermally stable than live preparations... 

As a manufactured product, a vaccine is composed of several components. A vaccine antigen(s) is a required component for any vaccine. Such a vaccine antigen can be part of a whole organism (e.g., live attenuated vaccine), a protective protein antigen, or an immune epitope. A live attenuated vaccine usually does not require a vaccine adjuvant that functions as an immune stimulant. However, killed whole organism or subunit vaccines usually need vaccine adjuvants. Otherwise, a weak or nonexistent immune response will be induced. Other vaccine components include vaccine vectors and vaccine preservatives. Databases of these vaccine components are briefly introduced here. 

Cholera vaccines consist of live attenuated or heat-kiUed Vibrio cholerae organisms. They can be given orally or parenteraUy. 

Vaccine A preparation of whole or parts of living, attenuated, or killed bacteria or viruses, (or synthesized antigens identical or similar to those found in the disease-causing organisms) designed to produce or increase immunity to a particular disease. 

Active immunization, vaccination, involves administration of an antigen as a whole, killed organism, an attenuated (live) organism, or a specific protein or peptide constituent of an organism. Booster doses often are required, especially when killed (inactivated) organisms are used as the immunogen. In the United States, vaccination has sharply curtailed or practically eliminated a variety of major infections, including diphtheria, measles, mumps, pertussis, rubella, tetanus, Haemophilus influenzae type b, and pneumococcus. 

While it is necessary to provide adequate precautions to personnel when freeze-drying hazardous products, overcautious risk assessment can result in unnecessary or even impractical working regimes. An example where risk assessment may require modification is where live attenuated vaccines are freeze-dried on an industrial scale, when it may be operationally impossible to handle such strains with the precautions essential when processing virulent strains of that organism. 

LOCKE, J.B., vicKNAiR, M.R., osTLAND, V.E., NIZET, v. and BUCHANAN, j.T. (2010) Evaluation of Streptococcus iniae kfiled bacterin and live attenuated vaccines in hybrid striped bass through injection and bath immersion. Diseases of Aquatic Organisms 89,117-123. 

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