Phase I/II study of a candidate vaccine designed against the B and E subtypes of HIV-1.

A phase I/II trial of a candidate vaccine to prevent HIV infection was carried out in Bangkok, Thailand, testing AIDSVAX B/E (VaxGen, Inc., Brisbane, CA), a bivalent subunit vaccine prepared by combining recombinant gp120 from a subtype B virus (HIV-1MN) with gp120 from a subtype E virus (HIV-1A244) in alum adjuvant. The studies provide human data on the immunogenicity of various dose combination of non-subtype B vaccine antigens. The results suggest that AIDSVAX B/E is safe and immunogenic in humans. The optimal dose for humans in developing countries was 300 microg of each antigen (B and E). Clade E responses were measurably increased by immunizing with gp120 B/E over B alone. Using the B/E combination did not interfere with the response to either clade. Antibodies to AIDSVAX B/E were able to bind to oligomeric gp120 on the surface of cells infected with primary isolates of HIV-1.

Incarceration and risk for HIV infection among injection drug users in Bangkok.

OBJECTIVE: To assess potential multiple relationships between incarceration and HIV infection among injecting drug users (IDUs) in Bangkok. Previous cross-sectional studies have shown strong relationships between incarceration and HIV infection but have not been able to assess potential causal pathways. METHODS: Injection drug users seen at methadone treatment programs in Bangkok were screened during 1995 to 1996 for enrollment into the study. With informed consent, 1,209 seronegative IDUs were enrolled in a cohort study to determine HIV incidence and identify factors associated with incident infections. Follow-up visits were conducted every 4 months, with HIV testing and assessment of risk behaviors. RESULTS: Overall incidence rate was 5.8 per 100 person-years (95% confidence interval [CI], 4.8-6.8) of follow-up. A four-step "injection risk" scale was constructed that included less frequent than daily injection, daily injection, daily injection with reported sharing of injection equipment, and injection while incarcerated. This scale was strongly related to HIV incidence, with incidence approximately doubling for each step in the scale. Incidence rate for follow-up periods that contained drug injection while incarcerated was 35/100 person-years at risk. In multivariate analyses, incarceration was related to incident HIV infection in multiple ways: previous incarceration and recent incarceration without drug injection, and the injection risk scale were all independently predictors of incident HIV infection. CONCLUSIONS: Incarceration is related to incident HIV infection through multiple pathways. Previous incarcerations are likely to serve as markers for unmeasured high-risk behaviors, and it is also highly likely that HIV is transmitted during periods of incarceration. Programs to reduce HIV transmission in jails and prisons, including drug abuse treatment of inmates and programs to reduce the likelihood of incarceration of IDUs, are needed urgently. Given the current diffusion of injecting drug use, of HIV infection among drug injectors, and of the common policy of incarcerating drug users, it is very likely that the problem of HIV transmission in jails and prisons is increasing in many countries throughout the world.