Trials on monkeys forwards HIV vaccine development

20160711000000, Tristan Manalac
An HIV vaccine that can lower the rate of acquisition and transmission may be in the immediate horizon, scientists claim in a recent paper. Published in Nature Medicine, the findings outline the result of a phase III clinical trial of the vaccine.

In particular, the researchers tested the RV144 vaccine, which has shown limited but significant protection from HIV, on rhesus macaques to evaluate its efficacy in preventing the spread of SIV, the simian counterpart of HIV.

The human immunodeficiency virus (HIV) targets and destroys the cells of the immune system. When the infection progresses, it manifests itself as the acquired immunodeficiency syndrome or AIDS.

Because the virus destroys the immune system, HIV/AIDS is usually characterised by a very weak immune response. Eventually, when the patient contracts other illnesses or infections, they will be essentially unable to combat it. Most of the times these (called opportunistic illnesses) can be fatal.

Currently, there is no cure for HIV. Further, because of its virology, once it is in the body, it cannot be removed by the immune system. Current treatment methods focus on controlling the infection, prolonging the life of the patient, and increasing the quality of life.

In the brightest cases, the patient can live an almost-normal life under some of the latest medication technologies.

However, because HIV has a long latency stage, early detection remains a problem. Indeed, if the patient does not practice regular screening, HIV can be difficult to detect before it becomes full-blown. Thus, the need for an effective vaccine is paramount.

This is what the current study aims to address by furthering the development of one of the most promising vaccines, RV144. In testing the vaccine on rhesus macaques, they also wanted to compare the enhancing effects of the alum adjuvant and the MF59 adjuvant.

The current formulation in trial uses the alum adjuvant to enhance the effects of RV144. However, in humans, HMF59 has been shown to induce a heightened and prolonged response. Thus, the team immunized the monkeys with the two formulations prior to challenging them with the SIV.

They found that RV144 with alum reduced the rate of infection by 44 percent, which corroborates the 31 percent value obtained from humans. Surprisingly, however, the team observed that RV144 with MF59 was not able to reduce the mode of acquisition significantly.

Further, the latter formulation only produced an immune response in the area of injection, thus disproving the previous hypotheses.

The team also discovered that RV144 interacts with several genes in the RAS pathway (a cell signaling cascade associated with a variety of cell physiological responses) which are associated with several subtypes of the immune response.

The findings represent one of the most recent advances in the development of an HIV vaccine. Further research and trials are necessary to assess and improve the efficacy and safety of the proposed vaccine. MIMS