Response of monkeys to vaccination with recombinant vaccinia virus which coexpress HIV gp160 and human interleukin-2.

Immunization of two macaque monkeys with recombinant vaccinia viruses encoding the env gene of HIV-1 (VV-gp160) resulted in demonstrable levels of gp160, gp120 and gp41-specific immunoglobulins in both animals. The virus used to immunize one of the monkeys additionally expressed the human IL-2 gene, which encoded human IL-2 (VV-gp160-IL-2). No toxic side-effects of vaccine-delivered IL-2 were observed. Despite marked attenuation of virulence by the coexpressed lymphokine, the levels of vector-specific antibodies in both animals were similar. Some differences in the HIV-specific reactivity patterns were detected. Serum reactivity of monkey #A56 (VV-gp160) was directed against gp41, whereas monkey #B58 (VV-gp160-IL-2) showed a wider range of recognition, with higher antibody titres against the HIV lysate preparation. Furthermore, this study demonstrates the capacity to boost antibody responses to the vector and coexpressed HIV antigens in primates which are already immune.