• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Development of salmonella vaccine

Extracts from this document...

Introduction

´╗┐DEVELOPMENT OF SALMONELLA VACCINE Abstract There are a number of specific characteristics to be considered when developing and manufacturing vaccines. Special characteristics for these vaccines comprise: 1. The appropriate level of attenuation, the balance between safety and immunogenicity, 2. The genetic stability of the organisms combined with environmental risk assessment, 3. The challenge of old-fashioned upstream and downstream methods in combination with quality control of the final product, and 4. The release requirements. Vaccination has proven to be the most efficient, cost-effective means for preventing a wide variety of infectious diseases. Vaccine development and manufacturing, however, poses several challenges. Inherent to all biological systems is the difficulty to achieve robust production processes guaranteeing reproducible efficacy and safety of the products. Highly automated bioprocess systems or advanced analytical systems used for closed-loop control may be a solution to overcome this. Yet these techniques are still not standard in the industrial environment or cannot be applied to vaccine production processes because of historical reasons, as some of the vaccines have been developed early in the previous century. Because vaccines are administered to healthy people, the efficacy and safety of vaccines are most important. Regulatory GMP (Good Manufacturing Practices) requirements are increasing to guarantee the safety of vaccines being developed and produced. ...read more.

Middle

Hence, vaccines have to undergo careful pre- and post licensure safety studies. 1. Regulatory Hurdles The vaccine must achieve the right balance between safety and immunogenicity. Additional issues include the potential for genetic reversion to partial or full pathogenicity, gene transfer into and out of the vaccine cells, and the potential risks for humans and the environment. For many vaccine candidates, the appropriate balance of attenuation and immunogenicity could not be met, and development of such candidates was consequently discontinued at an early stage of clinical evaluation. Hence, these safety issues have to be addressed very carefully during preclinical and clinical development. 1. Determining Safety and Efficacy In the case of Ty21a, safety and efficacy of the vaccine were demonstrated in a large number of clinical trials, with over 500,000 vaccinated children and adults in the US, Europe, Africa, Latin America, and Asia. Excellent tolerability and an overall protective efficacy of 67?80% were demonstrated for up to seven years in large field trials. The safety and tolerability profile of Ty21a was further confirmed in more than 200 million vaccinees during its more than 25-years of use worldwide. Recent post marketing surveillance has identified only mild and infrequent adverse events associated with Ty21a. ...read more.

Conclusion

Pharmacopoeia monographs are in place for the release testing of Ty21a. However, after internal testing and release by the vaccine manufacturers, each vaccine batch must undergo additional quality-control testing by regulatory authorities before it can be commercialized. Conclusion Live attenuated vaccines have numerous advantages over killed and subunit vaccines. However, they also have higher requirements regarding safety and quality. We have highlighted the challenges faced during preclinical and clinical development, as well as manufacturing and release testing for three attenuated live bacterial vaccines registered for human use?M. bovis BCG, S. typhi Ty21a, and V. cholerae CVD 103-HgR. When generating attenuated vaccines, attention must be given to the appropriate balance of attenuation and immunogenicity. We have demonstrated the progress in attenuation approaches from the empirical approach of the M. bovis BCG strain to the targeted attenuation of Ty21a and CVD 103-HgR. In the absence of correlates of protection of the vaccine, large Phase-3 field trials need to be conducted. Apart from ethical considerations caused by exposure of the trial participants to pathogens, potential side effects and safety issues are most prominent topics during the development and clinical trials of a vaccine. The orally administered Ty21a vaccine exhibits an excellent tolerability with an incidence rate of only 0.002% in addition to the absence of reversion to wildtype during the 30 years since its development. This clearly demonstrates the advantage of oral vaccination with a live attenuated vaccine. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our University Degree Microbiology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related University Degree Microbiology essays

  1. Free essay

    Identifying microorganisms using differential staining techniques

    Another difference is that a simple stain shows only the basic morphology and size of a microbe, but a differential stain like the gram stain differentiates the microbe into two categories, one being gram positive shown by a purple colour and the other being gram negative shown by a red or pink colour.

  2. Investigation into the effect of Temperature on the action of the Enzyme Lipase.

    In addition to this the graph of rate of reaction against temperature is not the same smooth curve as shown in my prediction and in many secondary sources. These results do however follow roughly the same trend as the prediction and secondary sources show, the graph of results does also show similarities to the prediction curve shown in the prediction.

  1. Bacterial Metabolism and Enzymatic Growth

    Ec and Pa were dyed, indicating a negative result; amylase was not produced by these enzymes since the starch did not catabolise. Lipolysis is the catabolism is lipids by the exoenzyme lipase. Lipids are triglycerides and are broken down to free fatty acids (Goldberg, 1996). It was present in P.

  2. COSHH Risk Assessment for a Laboratory

    3 As the details show this indicates it is corrosive and it is very harmful to skin. Hazards in the lab are not only limited to chemicals used but can be, material itself such as glassware that can cause harm if mishandled.

  1. Identification of an Unknown Enterobacteriaceae. The purpose of the experimental determination of an unknown ...

    Gas production was not seen in TSI. For phenylalanine deaminase test, 4-5 drops of 10% aqueous ferric chloride was added to the slant after which a green color developed indicating a positive result. S.I.M. showed a motile reaction demonstrated by the brushlike cloudy appearance in the test tube labeled "M".

  2. Distinguishing Species of Bacteria

    Table 6: Ideal Results for Urease Activity Name of Organism Urease Escherichia coli - Pseudomonas aeruginosa - Bacillus subtilis - Proteus vulgaris + The table above shows that the results for the urease from table 5 match the ideal result.

  1. Folic acid. In 1993 the Food and Drug Administration (FDA), in the USA suggested ...

    Eating fresh vegetables and fruits or microwaving can reduce the folate loss. WHY FOLIC ACID IS IMPORTANT Research has proved that folic acid can greatly reduce the chance of giving birth to a baby with neural tube defects (NTD's), such as spina bifida and anencephaly.

  2. This review looks at how silicification of bacteria allows preservation of the bacteria through ...

    In other case, low temperature (4-25oC) and moderate pressure (1-500) was used. [18] Although many studies had provided significant insights into predominantly diagenetic related fossilization processes, they provide little in mechanisms controlling microbial silicification in environments such as ancient oceans or the modern hot springs. Microscopic observations of many fossil samples revealed several notions of the silicification process.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work