BIOLOGIC APPROACHES TO THE PREVENTION OF SEXUAL TRANSMISSION OF HUMAN IMMUNODEFICIENCY VIRUS

Abstract

HIV prevention science has made progress, especially in Thailand and some sub-Saharan African countries. New cases of HIV in the United States, however, have not diminished and explosive epidemics in India and the People's Republic of China seem inevitable. Therefore, HIV prevention activities must move forward in parallel. Funding for biologic and behavioral research efforts must be balanced. Behavioral research must inform biologic strategies. In addition, HIV prevention efforts have been distorted by forces that require further consideration. First, the stigmatization associated with a diagnosis of HIV infection led to prevention efforts that virtually ignore the index case. Focusing entirely on the susceptible population puts intense and unrealistic pressure on behavior change and vaccine development. Although development of an HIV vaccine is desirable, there is no evidence that this goal can be achieved in the near future. Blind faith in vaccine technology detracts from pursuit of alternative aspects of prevention science. Vaccine development is but one of several key components to a broad-based prevention strategy. The history of control of infectious diseases has shown the need for targeting index cases. This certainly will prove important in HIV over the next few years. In developed countries, antiretroviral therapy for established HIV infection has become the standard of care. Increased knowledge of the biology of transmission of HIV suggests use of ART to prevent transmission. Such intervention must be accompanied by safer sex behavior in the index cases, and ultimately could lead to some form of monitoring and directly observed therapy. At this time, the latter approach seems unrealistic in developing countries, where the expense of drugs renders them unavailable. But there is every reason to believe that cheaper, more appropriate drugs will be developed before an effective vaccine. Furthermore, targeted use of ART might have disproportionate benefits in some countries. Women are the fastest growing HIV risk group. Several issues, both biologic and social, make this trend a concern. Increases in the number of HIV-infected women will lead to greater vertical transmission. Women possibly have different risk factors for acquisition and transmission than men. Information about the effects of vaginal ecology, specifically, the role of bacterial vaginosis, in the acquisition of HIV is essential because bacterial vaginosis can be reversed, at least transiently. To allow women to take an active role in HIV prevention methods, development of a topical microbicide is vital and may prove easier than a vaccine. Finally, HIV prevention efforts require knowledgeable, central leadership. All prevention efforts should be developed and implemented in parallel, to gain a synergistic result. Few vaccine experts are enthusiastic about microbicides, and HIV caregivers only rarely focus on the public health considerations of their patients. Stopping the spread of HIV requires a coordinated, concerted efforts using "all the tools in the toolbox."