HIV Prevention Strategies

CURRENT TREATMENT FOR PREVENTION STRATEGIES

Since HIV was discovered in 1983 [15] scientists have been working on numerous methods to prevent and cure the disease. There are a number of stages in the HIV lifecycle where infection and spreading can be interrupted, but ideally HIV needs to be stopped before the viral DNA is integrated into the host genome. A number of prevention methods have been created and tested by scientists; however few have yet been successful in preventing HIV infection. In this section, some prevention strategies for HIV will be discussed and the advantages and disadvantages of each method will be considered.

1. Pre-exposure Prophylaxis

Pre-exposure prophylaxis (PrEP) is a means by which the infection or spread of HIV can be prevented or controlled by antiretroviral drugs. It is consumed in the form of an oral pill which has to be taken regularly every day in order for it to work effectively. When used in conjunction with other prevention methods including the usage of condoms, PrEP is an effective way for an HIV-negative person at high risk of contracting HIV to prevent infection or spreading of the virus.

Tenofovir only has to undergo two phosphorylation steps, which means that it is activated faster than other NRTI’s, and as a result tenofovir is active in dividing as well as non-dividing cells [18], [19]. Emtricitabine also undergoes intracellular phosphorylation, and once this process has been completed it is incorporated into the viral genome and thereby prevents reverse transcription by causing DNA chain elongation to cease [18]. The combination of these two drugs proves very effective in the fight against the infection and spread of HIV.

Many PrEP drug trials have been conducted and are currently ongoing to establish the effectiveness of PrEP as an HIV prevention strategy. Table 1 presents the results of some of these trials. Most of the trials tested using the aforementioned Truvada tablets, while some used only tenofovir tablets or gels. The TDF2 trials conducted on heterosexual men in Botswana had an 80.1% reduction in HIV, which was the most successful result of all the trials conducted. As can be seen from the results, some of the trials were ended prematurely due to futility. A problem facing the scientific community is that of drug trials that have to be ended prematurely because they are not going to yield results that will be of use to scientists.

Table 1: Results of antiretroviral based oral and vaginal topical PrEP drug trials conducted in various countries on various population groups and sizes