GaJpin/DA/N2 IIIBenv 
that 6 - 24 hours is normally required for absorption, reverse transcription, and 
integration. Because of the nature of the PCR assay, it is unclear what proportion of the 
potentially transducible cells contain HIV-1 env DNA at each of the timepoints. The 
positive signal may represent as few as 2.5 transduced cells in the sample, because the 
assay can detect at least 2.5 copies of HIV-1 env DNA in a muscle preparation containing 
approximately 10-^ cell equivalents of genomic DNA. The detection of HIV-1 env DNA 
in the injection sites at day 7 and day 21 indicates that transduction had occurred in these 
animals. This shows that clearance of transduced cells to levels below 2.5 copies/1 0^ cell 
equivalents had not yet occurred for four out of four mice sampled at day 7 or day 21 . 
3.4 HUMAN IN VITRO MODEL 
Preclinical studies employing blood samples from HIV-infected individuals were 
designed to answer several questions about the ability of these individuals to respond to 
HIV-1 IIIB env epitopes presented by HIV-IT (V) transduced autologous lymphocytes 
These questions were: 
1. Can HIV-IT (V) transduce human lymphoblastoid cell lines from HIV- 1 -infected 
individuals for use as stimulators and targets in CTL assays? 
2. Will it be possible to develop a reliable human CTL assay which can be used to 
monitor human CTL responses to HIV-IT (V)? 
3. Will there be pre-existing levels of HIV- 1 -specific CTL in HIV- 1 -infected 
patients? 
4. Will pre-existing CTL levels be related to patient CD4 counts? 
5. Will in vitro human CTL responses be specific to the HIV-1 IIIB strain 
represented by HIV-IT (V) or will crossreactivity be observed, comparable to that 
exhibited by the mouse CTL on HIV-1 infected human targets (Section 3. 1.1.6)? 
To attempt to evaluate the biological effect of HIV-IT (V) on CTL activity in HIV 
infected humans, an in vitro system was developed to reliably measure HIV-1 specific 
CTL. Autologous Epstein-Barr virus (EBV) transformed cell lines were derived from 
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