expressing the HIV-1 IIIB ENV/REV proteins (BCenv), whereas no significant lysis of 
the control BC cells was observed. Results from additional studies have indicated that: 
(1) multiple (two or more) injections are preferable, (2) the intramuscular (IM) route is 
adequate, (3) the cytotoxic effector cell population is comprised of CD8 + , Class I MHC 
restricted CTL, and, (4) the specificity of the CTL response is directed against the HIV- 
1 ENV and REV protein determinants. 
Figure 1 
HIV-IT (V) CTL Induction 
0082-0 l/DV CTL induction 
CTL Induction in B ALB/c mice injected IM with HIV-IT (V). Stimulated effector cells were tested on 
HIV env/rev-expressing (BCenv) and control (BC) target cells using a standard 51 Cr-release cytotoxicity 
assay. 
CTL induced with HIV-IT (V) show cross-reactivity against determinants of different HIV- 
1 isolates. HIV-IT (V)-induced CTL are capable of lysing target cells coated with a peptide 
(PI 8 IIIB) derived from the V3 region of the HIV-1 DIB envelope protein and exhibit 
cross-reactive lysis of target cells coated with the P18MN peptide derived from the 
equivalent V3 region of the HIV-1MN envelope protein (Figure 2). Similar CTL cross- 
reactivity directed against human/mouse-MHC target cells infected with different, more 
prevalent U.S. prototypic viral strains and clinical HIV-1 isolates has been demonstrated 
following immunization of mice with syngeneic cells transduced with HIV-IT (V). In 
contrast to type-specific antibody responses, the HIV-IT (V)-induced CTL response 
appears to exhibit broad reactivity against cells infected with diverse HIV-1 strains. 
Mice treated with HIV-IT (V) have also produced antibodies that specifically react to the 
HIV-1 BIB envelope protein. Mice were immunized with up to three intramuscular 
injections of HIV-IT (V) and their serum tested for reactivity (binding) to gpl20 (Figure 3). 
Other studies have shown that antibodies that bind to a peptide derived from the V3 region 
of the HIV-1 BIB envelope protein do not cross-react with a peptide derived from the 
equivalent region of the HIV-1 MN isolate. 
[696] 
Recombinant DNA Research, Volume 18 
