Question

You have been asked to express the cystic fibrosis-linked chloride channel selectively in the lung epithelial cells of mice. Since these are dividing cells, to achieve this you use the retroviral technology. The vector containing the chloride channel gene (pRevTRE-chloride channel cDNA) is packaged into live viral particles in a packaging cell line (PT67) and then the viral particles secreted into the medium are injected into mouse lung epithelium. The vector pRevTRE-chloride channel contains the LTR and packaging sequence ψ. Would these injected viral particles replicate in the injected mouse?

A.

No; the packaging cells express proteins that recognize the LTR sequence and promote packaging and replication of the virus

B.

Yes; the ψ sequence is enough for the formation of a viral particle, but the packaging cells contain gene products that stabilize the virus particles

C.

Yes; however, without the packaging cells, the newly formed viral particles are readily lysed in the mouse epithelial cells

D.

No; the packaging cells express the gal, pol, and env proteins that are needed along with the ψ sequence to form the replicating viral particle

these are the only information provided

Answer 1

Answer: No; the packaging cells express the gal, pol, and env proteins that are needed along with the ψ sequence to form the replicating viral particle

The LTR helps in integration of the gene of interest into the mouse genome; it doesn't directly help in fornifo new viral particles. TheThe packaging sequence (psi) alone is not sufficient for the virus to replicate. It needs the gag, pol and env genes in order to replicate and form fully packaged virion particles. These genes are present in the packaging cell line which helps in producing new virus particles. So with only the psi sequence in it, the injected viral particles will not be able to replicate in the injected mice.