Recombinant DNA Advisory Committee - 06/1-2/92 
Leventhal asked whether or not the patients on this study will be allowed to receive 
conventional therapy in addition to the experimental therapy? She noted that the 
eligibility for the two protocols was different. 
Dr. Leventhal asked the investigators to explain the reasoning for giving different 
numbers of cells for each of the two protocols. 
Dr. Murray asked the investigators to address future plans for establishing animal models 
since they have not proposed one. Dr. D. Miller stated that a monkey model is 
available. Since the TAR regions of Simian Immunodeficiency Virus (SIV) are similar 
to HIV, this animal would be an appropriate model to test the vector. 
Presentation-Dr. Smith 
Dr. Murray called on Dr. Smith to respond to the questions presented by the primary 
and secondary reviewers as well as the other committee members. Dr. Smith stated that 
the rationale behind this proposal is that a complex between the 5' end of the HIV 
messenger RNA (mRNA) from TAR forms a complex with the HIV encoded protein 
TAT and at least one or more cellular proteins. This complex is an absolute 
prerequisite for HIV transcription and HIV replication. Short RNA sequences, called 
TAR decoys (DCTAR), mimic the 5' region of the nascent HIV mRNA. Since the TAT 
is sequestered, the complex is rendered inactive. 
Dr. Smith said that the original in vitro assays were performed with DCTAR transduced 
CEMss cells that were selected for neomycin resistance in G418. These subclones were 
found to express very high levels of DCTAR RNA. When these subclones were 
challenged with HIV, a 99% inhibition of HIV reverse transcriptase was observed. 
These cultures were maintained for 21 days. 
Dr. Smith said that the ideal in vitro experiment would be to transduce totipotent stem 
cells with DCTAR; however, he has not been able to achieve efficient transduction 
frequencies in this cell population. 
Dr. Smith presented data regarding the transduction of CD4( + ) peripheral blood T cells. 
The CD4( + ) cells were treated with PHA and IL-2 for 24 to 48 hours, followed by 
coculture with the vector producing packaging cell lines. RNA and DNA analysis 
revealed a 10-20% transduction efficiency. These cells were cultured for several days 
prior to HIV challenge. 
Dr. Parkman inquired as to whether or not in situ hybridization assays were performed? 
Dr. Smith responded that all attempts to perform these experiments have been 
unsuccessful. Dr. D. Miller asked how the patient material would be analyzed for 
Recombinant DNA Research, Volume 15 
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