1. The information below is from a box of typhoid vaccine. VIVOTIF BERNA® Typhoi
ID: 303124 • Letter: 1
Question
1. The information below is from a box of typhoid vaccine.
VIVOTIF BERNA®
Typhoid Vaccine
Oral Ty 21a
Explain how you would know by simply reading this label that this is an attenuated vaccine. (Hint: Vivo means "life" in Latin and the lowercase “a” does stand for attenuated, but these are not the answers I am looking for.)
2. Explain how the bacterium is attenuated in the Vivotif vaccine and why this attenuation prevents the the bacteria in the vaccine from causing typhoid fever. (Note: You will find the answer in the product insert for the drug under “Clinical Pharmacology.” Be specific and thorough in your response.)
3. Typhim Vi® is another typhoid vaccine.
What is the antigen in this vaccine and specifically where does it come from? (Note: Don’t just copy the information from the product insert. Address cell structure and composition of the antigen in your answer.)
4. The Typhim Vi® vaccine is a(n) _____ vaccine.
a. sub-unit
b. inactivated
c. attenuated
5. Explain why re-immunization with the Vivotif® vaccine is recommended every five years, but is recommended every two years for the Typhim Vi® vaccine. (Note: Use your knowledge of immunology to answer this question).
Helpful Links:
Typhoid Vaccine Information
• Immunization Action Coalition Click on “Typhoid.” http://www.immunize.org/fda/
• World Health Organization [WHO] Click on “Typhoid” http://www.who.int/immunization/diseases/en/
Explanation / Answer
1) Attenuated vaccines are inactive forms of bacteria which have lost the ability to reproduce and multiply in Short period of time. They take a longer time in reproducing and replication which gives the immune system ample of time to produce sufficient antibodies against the infection. Typhoid causes its affects in the gastro intestinal tract and for treatment, administering vaccines from oral route passing all the mucosal tract is effective and most of attenuated vaccine are administered orally and by seeing the label as oral administration we can say that it is attenuated vaccine.
2) Salmonella typhi bacteria is very efficient in growing on human cells for generation of attenuated vaccines some culture of bacteria are grown on the medium containing a digest of yeast extract, an acid digest of casein, dextrose and galactose. Initially these bacteria find it difficult to grow on media as they grown well on human cells but after a long time these bacterial cells starts to grown on the media. Once they grow on the media they looses the ability to grow on the human cells and these bacterial cells will be ineffective in attacking human cells. These live attenuated bacterial cells are taken and used as vaccine. Though they are ineffective but take a longer time to grown on human cells which proves ample time for human immune cells to generate a immune response.
3)Thypim VI is polysaccharide vaccine which contains a sterile solution with the cell surface polysaccharide VI. The bacteria are grown on casein media after growth the polysaccharide is separated from the supernatant after centrifugation by adding hexadecyltrimethylammonium bromide.
4) Inactivated vaccines
In the polysaccharides are inactivated and used as vaccines.
5) Vivotif uses the inactive form of virus which may take longer time to grown on human cells until then it remains inactive in the body and immune cells gets frequently contacted with the bacterial cells generating immune response which last for years while the Thyphim VI uses the part of bacterial cell that is polysaccrides VI which are more prone to less immune response and the immune cells produced against polysaccharides cells may die after certain time hence re immunization is needed after 2 years. While the attenuated bacterial cells are present in the body which generates the immune response frequently.
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