Question

BACKGROUND READING:

The Gates Foundation is interested in developing vaccines, and supports the Global Alliance for Vaccine Development (GAVI). He would be very interested in funding projects that provide novel delivery mechanisms for vaccines. Frederica has always wanted to find a way to make a vaccine for S. pneumoniae that targets all of the serotypes! This may be her opportunity! Her goal is one vaccine that would be completely protective against all strains of S. pneumoniae. She has an idea to make an edible vaccine that would contain the antigen derived from S. pneumoniae. Frederica decides to try using yogurt as the delivery mechanism! She wants to clone a gene from S. pneumoniae that encodes an antigen and to express this gene in a microorganism that would grow in yogurt. Eating the yogurt would serve as the vaccine delivery. Consider the various molecules expressed by S. pneumoniae.

This question about choosing one molecule serving as an antigen HAVE BEEN ANSWERED BY ME!!!

Choose one molecule that would be an appropriate choice to serve as the antigen for the vaccine preparation. What molecule have you chosen? I chose PspA

ADDITIONAL BACKGROUND READING:

For the vaccine she must incorporate the gene for the S. pneumoniae antigen into a bacterium that will survive in the yogurt and will express the gene producing the antigen molecule. One organism found in yogurt is Streptococcus thermophilus. Frederica begins her plan to transform S. thermophilus with a plasmid vector encoding the antigen gene. First Federica must choose a plasmid cloning vector. Frederica understands that a gene encoding resistance to antibiotics is commonly used to select for recombinant organisms (she does not want to include such a gene in her final construct for fear that it would be transferred to normal flora in the gut of the immunized children). As such, her final recombinant S. thermophilus strain will need some further genetic manipulations. However, for a phase one study, where the vaccine will be tested in the laboratory in animals, it is ok.

QUESTIONS:

1. Prepare a drawing of the cloning vector that you would use. Be sure that your drawing contains all of the essential information needed to demonstrate:

i. That the plasmid will replicate in S. thermophilus
ii. Any other genes that you will need to identify your transformants.

2. Prepare a diagram that shows how to construct a recombinant plasmid that would contain the gene that encodes your antigen.

          a. What is the role of restriction endonucleases in the process of constructing your plasmid?

          b. What is the role of DNA ligase in this process?

          c. Consider the plasmid that you have designed. How will you identify S. thermophilus cells that have been transformed with this plasmid?

          d. For the vaccine to be functional, the antigen needs to be expressed. Do you need to add anything to the media to ensure expression? How will you determine if the protein is expressed?

Answer 1

1. ANS:

Aut cal BamMI EmR Vector fer herm lu