Contents:
Introduction
Disease
Vaccines
Issues
Introduction
It is estimated that 32.4 million adults and
1.2 million children will be living with HIV by the end of 2000; 90% of
those individuals will be living in the developing world. Since its
appearance and rapid spread, HIV infection has become one of the leading
causes of death in the developing world with increasing social, political
and economic consequences. While treatment exists in the form of
drug therapies, access to these drugs is limited to the industrialized
world. No vaccine currently exists for the HIV vaccine. Because
of the rapid spread and continuing growth of this infection, it is imperative
that ah HIV vaccine be developed.(1)
children infected with the HIV virus
Disease
HIV is a viral infection caused by the Human
Immunodeficiency Virus. The virus attacks the immune system, targeting
CD4 positive cells, slowly eliminating T helper cells from the body.
An advanced stage individual is categorized as having AIDS, or Acquired
Immune Deficiency Syndrome, and is susceptible to any number of opportunistic
infections.
HIV can be transmitted with HIV-1 infected cells or by cell-free virus. Thus, to successfully develop a vaccine against the infection, both of these modes of transmission will need to be addressed. (2)
For more in-depth information on the HIV retrovirus
and pathogenesis, please reference the Vaccine homepage HIV website, a
comprehensive look at the HIV virus and infection, created by a past Bio
160 student. (3)
http://www.brown.edu/Courses/Bio_160/projects/hiv/hiv.html
The development of a vaccine against the HIV
virus has been challenged by several unique aspects that limit the traditional
approach to vaccine development. These factors include
1) the lack of understanding of HIV in general
2) the lack of appropriate animal model
3) the fact that the ìcorrelates of immunityî
are still unknown
Several types of vaccines have been investigated for use. It is generally agreed that the use of whole inactivated virus or live attenuated virus vaccines are too dangerous because of the possibilities of reversion into the virulent form. Thus, many vaccine trials have focused on the use of subunit vaccines or recombinant DNA virus vaccines placed in viral vectors that have limited capacity to reproduce. Most researchers believe that a successful vaccine would have to elicit an effector T cell response, to eliminate virally infected cells, while also producing antibody responses, to neutralize cell free virus. (4)
For a more indepth discussion and presentation on the numerous HIV vaccines currently in Phase I, II, and III, trials, as well as the different vectors being investigated to elicit both a cell-mediated and a humoral response, please reference the "Vaccine Strategies" section and the "List of Vaccine Trials" in the homepage of a fellow Bio 160 student.
http://www.brown.edu/Courses/Bio_160/projects/hiv/hiv.html
Issues
The issues surrounding the development of a vaccine for HIV are
numerous.
*The Economics of Vaccine Development
and Program Implementation
*Ethics
of Clinical Trials in Developing Countries
*Disease Surveillance