The search for an HIV vaccine

See also Education and debate p 226

HIV infections and deaths from AIDS continue to ravage many countries around the world, with most infected people living in the poorest nations.1 In terms of morbidity and mortality, the HIV/AIDS pandemic is worse than the Black Death of the 14th century. The search for an HIV vaccine was seen as the logical solution to the burgeoning epidemic soon after the discovery of HIV, but early enthusiasm became muted as the realities of the challenge became evident.2^–4

Nevertheless, there are scientific reasons why there is hope that an HIV vaccine will ultimately be developed. Firstly, studies of non-human primates that were given candidate vaccines based on HIV or SIV (simian immunodeficiency virus) have shown either complete or partial protection against infection with the wild type virus. 5 6 Secondly, successful vaccines have been developed against other retroviruses.7 Thirdly, almost all humans develop some form of immune response to HIV infection, with some exposed people remaining uninfected or developing immune responses that are protective or that are able to control the viral infection over long periods.8 Some people have remained free of disease for up to 20 years, often with undetectable viral loads. 9 10 A group of sex workers from Nairobi and South Africa has remained HIV negative despite continuing high risk exposure; resistance to HIV infection in these people is thought to be due to their ability to mount protective immune responses to HIV, rather than to any innate host genetic factors. 11 12 This group has provided insights into strategies for developing a vaccine.