Galpin/DA/N2 IIIBenv 
3.1. 1.2 Dose Response 
To more specifically assess the dose range required to induce CTL activity 
using a single lot of crude, formulated HIV-IT (V), mice were given a single IP 
injection of various doses of HIV-IT (V). CTL induction was achieved with a 
single dose of 1.6 x 10 6 HIV-IT (V) cfu, whereas injection of 8 x lO-^ cfu or less did 
not induce cytotoxic activity (Figure 9 A). However, two HIV-IT (V) injections of 9 
x 10 4 cfu or greater resulted in marked cytotoxic activity (Figure 9B). Thus, 
cytotoxic activity could be obtained following single or multiple injections of HIV- 
IT (V) in a dose-dependent manner. These studies demonstrated that administration 
of multiple low-dose treatments or a single high-dose treatment can induce 
comparable CTL responses. 
3. 1.1.3 HIV-IT (V) Encoded Proteins Induce the CTL Response 
The specificity of the effector CTL induced with HIV-IT (V) was 
examined. As described previously, the N2 IIIBenv provector used to produce 
HIV-IT (V) encodes three gene products: the HIV-1 env protein; the HIV-1 rev 
protein; and the neomycin resistance (neo r ) protein. Theoretically, the 
HIV-IT (V)-induced CTL could be directed against each of these provector-encoded 
proteins or vector associated components. Therefore, studies were designed to 
evaluate the specificity of the HIV-IT (V)-induced CTL response. 
HIV-IT (V)-induced CTL effectors were tested for their ability to lyse 
vector-transduced target cells expressing (Tgalactosidase (P-gal) and neo r , but not 
expressing HIV-1 env or rev proteins (BC-(3gal), and such lysis compared to the 
BCenv target cell which expresses HIV env, rev and neo r proteins. B ALB/c mice 
were injected IP once with purified formulated HIV-IT (V) (4 x 10^ cfu) and the 
primed splenocytes were stimulated in vitro with irradiated BCenv cells. The 
resulting HIV-IT (V) induced CTL exhibited lysis of only the HIV-1 env/rev/neo r 
expressing BCenv target, whereas negligible background lysis was observed on the 
Recombinant DNA Research, Volume 17 
