Galpin/DA/N2 IIIBenv 
mutation 23 , 24 following prolonged treatment with AZT or any single RT inhibitor. It is 
unclear whether combination therapy will be totally successful in suppressing this 
emergence. For these reasons, alternative therapies to be used singly or in combination are 
actively being sought. 
Due to this lack of any proven long-term anti-viral therapy for HIV-1 infected patients 
and the predictable terminal outcome of this infection, (i.e., death) in over 75% of infected 
individuals, the potential benefit of gene therapy using retroviral vectors far outweighs the 
perceived risks associated with this technology. 
The induction of CD8 + cytotoxic T lymphocytes (CTL) potentially reduces the 
lymphocyte and monocyte-macrophage reservoirs of HIV-1. Reduction in infected 
lymphocyte and macrophage populations may prevent cell or tissue injury such as 
progressive neurotoxicity or progressive immune deterioration from viral direct, indirect, or 
induced toxins. Therefore, successful treatment- induced activity (CTL and antibody) may 
halt disease progression in asymptomatic subjects and reverse disease manifestations in more 
advanced HIV-infected individuals provided their immune system is capable of generating 
appropriate immune responses. 
2.0 VECTOR CONSTRUCT, PACKAGING AND PRODUCER CELL 
LINES 
2.1 VECTOR CONSTRUCT 
The N2 IIIBenv provector backbone is a modified form of the N2 retroviral 
provector 25 with the gag AUG mutated to ATT. The insert was obtained from pAFenv 
SV 2 neo 26 and consists of the env and rev genes from HIV-1 IIIB as the 5' genes driven 
from the MoMLV LTR. In addition, the neo r gene driven from the SV40 early promoter 
is included as the 3' gene to allow selection of transduced cells. The construction and 
component parts of the N2 IIIBenv provector are shown in Figure 1 . 
23 Gao, Q., et al., Antimicrobial Agents and Chemotherapy , 37:130-133 (1993). 
24 Mohri, H„ et al., Proc. Nall. Acad. Sci. USA, 90:25-29 (1993). 
25 Aramentano, et al., J. Virol, 61:1647-1650, (1987). 
2 ^Wamer, J.F., et al., AIDS Research and Human Retroviruses, 7:645-655 (1991). 
T- 
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