Nh. Carbonetti et al., Stimulation of HIV gp120-specific cytolytic T lymphocyte responses in vitro and in vivo using a detoxified pertussis toxin vector, AIDS RES H, 17(9), 2001, pp. 819-827
CD8(+) cytolytic T lymphocytes (CTL) are almost certainly an important comp
onent of a potentially protective immune response to HIV. To test the abili
ty of pertussis toxin (PT) to deliver an HIV-derived major histocompatibili
ty complex (MHC) class I peptide for CTL stimulation, we constructed a fusi
on of the gp120 P18-I10 CTL epitope with a genetically detoxified derivativ
e of PT (PT9K/129G) and assayed this fusion for its ability to stimulate a
gp120-specific CTL response in vitro and in vivo. Antigen-presenting cells
incubated with this fusion protein were lysed by P18-I10-specific CTL in vi
tro and this activity was shown to be MHC class I restricted. The activity
was inhibited by brefeldin A but was not inhibited by proteasome inhibitors
, possibly because PT undergoes retrograde intracellular transport through
the Golgi apparatus to the endoplasmic reticulum and delivers epitopes dire
ctly to nascent class I molecules. Mice immunized intraperitoneally with a
single dose of the fusion protein without adjuvant raised a strong gp120-sp
ecific CTL response in the spleen. This CTL response was dependent on (1) t
he dose of fusion administered, (2) the fusion of the epitope with the toxi
n (since coadministration of peptide and toxin gave no response), and (3) t
he activity of CD8(+) cells. These data demonstrate that this detoxified de
rivative to PT, which is already a component of a licensed vaccine for huma
ns, could represent a useful vaccine vector molecule for stimulation of HIV
-specific CTL responses.