Immunization of Chimpanzees with the HIV-1 Glycoprotein gp160 Induces Long-Lasting T-Cell Memory

The goal of the present study was to investigate the antigen-specific T-cell response to the recombinant HIV envelope glycoprotein (gp160) and to test the effect of various adjuvant formulations on the efficiency of T-cell priming as well as on magnitude and longevity of the gp160-specific T-cell response. Our studies revealed that, in combination with an appropriate adjuvant (lipid-based adjuvant or mineral carrier complex), immunization with recombinant gp160 led to the appearance of gp160-primed T cells. The T-cell response obtained was substantial (proliferative response of > 100,000 Δdpm after one primary and two booster immunizations), gp160-specific (proliferation only in response to gp160, no proliferation after addition of a mock gp160 preparation), and long-lasting (T cell responses of >50,000 Δdpm were observed more than one year after the last booster). The results presented here differ from those of previous studies in that they show the presence of substantial and long-lasting T-cell memory toward the immunogen gp160. Therefore, further investigations on the use of these preparations as HIV candidate vaccines appear to be justified.