Your organization wishes to prepare 1 kg of HIV gp120 protein to be employed as a diagnostic product antigen for the diagnosis of human infection with HIV (the causative agent of AIDS). There are several options:
a. prepare the infectious virus, lyse the virions, and isolate and purify gp120 from the virion envelopes,
b. clone the gp120 gene from the viral genome, and express the gene in IDNA-modified E. coli,
c. clone the gp120 gene and express the gene in transgenic animals which are not immunologically competent (e.g., SCID mice).