RNAi (RNA interference) is a recently discovered phenomenon that has burst on to the forefront of genetic research
and immunology. Indeed, the discovery and understanding of RNAi can be said to be one of the greatest scientific advancements of the last decade. RNAi appears to be an ancient and widespread genetic immune mechanism. Recent breakthroughs have shown that RNAi plays an important role in defending against several types of viruses and is also involved in a number of regulatory mechanisms within the cell.
The primary reason for increasing interest in RNAi research is the fact that RNAi can be manipulated and exploited to target certain viruses and therefore opens up the possibility of directly treating viral infections. Another important aspect of RNAi is that it could be potentially used to silence the expression of particular genes to facilitate the study of gene functions.
While the basic qualities and characteristics of the process of RNAi has recently been discovered, it must be emphasized that RNAi research is still at a nascent stage and scientists are far from a deep and quantitative understanding of the phenomenon. Many of the experiments in this area are currently being performed using trial and error models and rules of thumb. Scientist are in the process of developing more predictive and quantitative models using bioinformatic techniques.
Although a number of geneticists recognized the importance of RNAi at a very early stage, many remained skeptical regarding its potential as a therapeutic tool. RNAi was regarded more as a tool that facilitated the study of particular genes and their functions. Today, the significance of RNAi research is attested by the fact that the recent Nobel Prize in physiology has been awarded to the American research duo of Andrew Fire and Craig Mello for their contribution to this field. Interest in RNAi as a tool of alternative therapy is growing rapidly and it is not unreasonable to expect that we might start seeing significant results before very long.
The main hurdle in using RNAi for therapeutic gene silencing is the process of injecting RNA into the cell. Transferring hydrophilic RNA molecules across the hydrophobic cell membrane
poses a serious problem for RNAi researches. Appending RNA to something else, such as nanoparticles, is one of the many approaches that RNAi researchers have devised to solve this problem. Another hurdle when it comes to RNAi therapy is longevity. The gene silencing achieved through RNAi needs to be prolonged for a number of days, so as to be a viable treatment appropriate for human beings.
Needless to say, the allure
of RNAi therapy has scarcely escaped HIV researches. In 2002, scientists at MIT announced that they had used RNAi to inhibit the progress of various stages in the life cycle of the HIV virus. However, the rapidity with which the HIV virus mutates and evolves makes it particularly resistant to therapy of any sort, let alone RNAi. Moreover, it must be stressed that most experiments in RNAi therapy, including this one, have been performed in laboratory conditions. Broader applicability of RNAi therapy in the context of human patients is still a million dollar question.