[Randomization of a population for a clinical trial of immunization against the human immunodeficiency virus (HIV)]. / Randomisation d'une population pour un essai clinique d'immunisation contre le virus de l'immunodeficience humaine (VIH).

Serum HIV antibodies has been investigated in different subpopulation from four different regions in Zäire by Elisa (Elavia Pasteur) and Western Blot. Seropositive prevalence differed from 2.4% (rural population) to 12.5% (urban population) according to the regions. When the group with 2.4% migrated to the area with 12.5% positives, after 8-12 months the number of seropositives in this group raised to 8%, showing an increase of 5.6% within one year. Such population is suitable for a large scale clinical trial (with anti-AIDS vaccine) to be performed on individuals with high risk of natural infection.

PIP: Major obstacles to development of a vaccine against the HIV infection have apparently been resolved by utilizing viral signals not directly from the virus or its products, but from membranes of infected cells. Evaluation of the level of protection provided by the vaccine requires a large scale clinical trial in a population with a high rate of infection. Screening studies have been conducted in different areas and in different subgroups in Zaire in order to identify such a group. A population living or working at a site some 30 km east of Kinshasa was studied between December 1986-March 1988, and a parallel study was conducted of persons residing in Kinshasa. Groups from 2 rural regions were also studied. The 1554 persons screened were divided into 8 groups based on their residence histories. Serum HIV antibodies were assessed by ELISA and Western Blot. The 4 groups composed of men living and working in Kinshasa or within a suburban radius of 30 km had a seroprevalence rate of 12.67%, with no significant difference by residence. A population of 136 pregnant women in the same locations had a seroprevalence rate of 12.5%, for a sex ratio of 1.1. A group of 71 persons studied in a provincial city of southern Zaire who had spent time in Kinshasa several years previously had a seroprevalence of 4.23%. A group of new arrivals to the Kinshasa vicinity from the provinces who had never previously resided in Kinshasa had a seroprevalence of 2.45%. The final group was also composed of new arrivals from the same provinces with no previous urban experience. Screening after 8-12 months in the city showed that their seropositive rate had increased from 2.45% to 8.00%. This increase of 5.6% within 1 year indicates that this group would be appropriate for a large scale clinical trial on individuals with high risk of natural infection.

[Immunization against the human immunodeficiency virus in Zaire]. / Immunisation contre le virus de l'immunodéficience humaine au Zaïre.

The first experimental immunization of human against the AIDS retrovirus HIV-1 was started in a series of HIV seronegative healthy volunteers in november 1986. Priming used a vaccinia virus recombinant (V25) expressing Gp 160 env determinants of HTLV III B at the surface of infected cells. This priming which induced a weak immune reaction was performed on HIV seronegative French and Zaïrian individuals living in Zaïre (Kinshasa). These results prompted to boost the primary immune response. Four different protocols were used: slow drip intravenous infusion with paraformaldehyde fixed autologous cells infected with V25 (first protocol), repeated scarification with V25 for the second protocol. The third protocol used scarifications with fragment of Gp 120 env protein, and the fourth protocol used intramuscular injections of purified autologous cell membrane infected with V25. Results of the immune reaction obtained after these boosts: The three last protocols showed a cell mediated immunity (CMI) that not significantly enhanced in comparison with CMI obtained after V25 priming alone. Moreover, the sera showed low and variable neutralizing antibodies titers one to four months after boosting. By contrast boosting with V25 infected fixed cells (D.Z. individual) provide strong humoral and cellular group specific anamnestic immune response. Indeed, high levels of antibodies to viral envelope and neutralizing antibodies against divergent HIV-1 strains were observed. Group specific CMI and cell mediated cytotoxicity were enhanced by boosts. Skin-tests showed high mediated and delayed hypersensitivity to GP 160 in vivo. For the first time, these results show that an immune stage against HIV can be obtained in a man.

PIP: The 1st experimental immunization of humans against the AIDS retrovirus HIV-1 was begun in November 1986 among a group of HIV-seronegative healthy volunteers. A priming, involving a vaccine virus recombinant (V25) expressing Gp 160 env determinants of HTLV-III B at the surface of the infected cells was utilized. This priming, which induced a weak immune reaction, was performed on HIV-seronegative French and Zairian individuals living in Kinshasa, Zaire. These results prompted a boost to the primary immune response. 4 different protocols were used: the slow drip intravenous infusion with paraformaldehyde-fixed autologous cells infected with V25; repeated scarification with V25 for the 2nd protocol; scarifications with fragments of Gp 120 env protein; and intramuscular injections of purified autologous cell membrane infected with V25. The results of the immune reaction obtained after these boosts indicated the following: The last 3 protocols showed a cell- mediated immunity (CMI) that did not significantly enhance in comparison with CMI obtained after V25 priming alone. Moreover, the sera showed low and variable neutralizing antibody titers 1-4 months after boosting. By contrast, boosting with V25 infected fixed cells (D.Z.) provided strong humoral and cellular group specific anamnestic immune responses. Indeed, high levels of antibodies to viral envelope and neutralizing antibodies against divergent HIV-1 strains were observed. Group- specific CMI and cell mediated cytotoxicity were enhanced by boosts. Skin tests showed high mediated and delayed hypersensitivity to Gp 160 in vivo. For the 1st time, these results show that an immune state against HIV can be obtained in a man. (author's modified)