All patients continue their antiretroviral regimen during the study. Twelve patients are assigned equally to 1 of 3 cohorts; all patients receive 4 doses of C4-V3. Cohort 1 receives C4-V3 alone; once all 4 patients have received 2 doses and completed 8 weeks of treatment, toxicity data are reviewed. Barring serious adverse events, 4 patients are enrolled in Cohort 2 to receive C4-V3 plus a low dose of IL-12 near the vaccine injection sites. Once all 4 patients have received 2 doses of C4-V3/IL-12 and completed 8 weeks of treatment, toxicity data are reviewed. Barring serious adverse events, 4 patients are enrolled in Cohort 3 to receive C4-V3 plus a higher dose of IL-12 administered as above. [AS PER AMENDMENT 8/1/00: Twenty patients are assigned equally to 1 of 5 cohorts; all patients receive 4 doses of C4-V3. Cohort 1 receives C4-V3 alone; once all 4 patients have received 2 doses and completed 6 weeks of treatment, toxicity data are reviewed. Barring serious adverse events, 4 additional patients are enrolled in Cohort 2 to receive C4-V3 plus a low dose (dose level 1) of IL-12. Barring serious adverse events, 4 additional patients are enrolled in Cohort 3 to receive C4-V3 plus a higher dose (dose level 2) of IL-12. Barring serious adverse events, 4 additional patients are enrolled in Cohort 4 to receive C4-V3 plus a higher dose (dose level 3) of IL-12. Barring serious adverse events, 4 patients are enrolled in Cohort 5 to receive C4-V3 plus a higher dose (dose level 4) of IL-12.] Patients are followed for safety evaluations and changes in viral load through Week 48. If toxicity related to C4-V3 or IL-12 persists through Week 48, the affected patients are followed until resolution of the toxicity.