“Rise and rise again, until lambs become lions”. The meaning of this phrase is never give up until we achieve our goals.
Why I write this post because I would like to show my appreciation to the scientists who are optimist in developing DNA drugs after the false start. DNA Drugs is the vaccine contains plasmid that carried DNA sequence of the pathogen, so that the immune system can produce antibody as preparation to fight the infection of the disease.
Why I mean the “false start” is because the DNA Drugs has the head-to-head competition with another potential vaccine that using adenovirus as carrier of DNA of pathogen seems not very effective with the latter vaccine. The competition is their compare the immune response of two vaccines. The DNA Drugs contains plasmids, each carrying a gene for one of five HIV proteins. Its goal was to get the recipient’s own cells to make the viral proteins in the hope they would provoke protective reactions by immune cells. The second vaccine used another virus called an adenovirus as a carrier for a single HIV gene encoding a viral protein.
The DNA recipients displayed only weak immune responses to the five HIV proteins or no response at all, whereas recipients of the adenovirus-based vaccine had robust reactions. To academic and pharmaceutical company researchers, adenoviruses clearly looked like the stronger candidates to take forward in developing HIV vaccines.
What I say they are optimistic, after the disappointing result of DNA drugs they did not just give up, they find what are the mistakes. The main reasons for those failures seemed to be that vaccine plasmids were not getting into enough cells and, where they did penetrate, the cells were not producing enough of the encoded proteins. As a result, the immune system was not being sufficiently stimulated.
The vaccines using adenovirus seems have a bigger problem. In 2007 pharmaceutical company Merck initiated a large trial of an HIV vaccine that used an adenovirus called AdHu5 to deliver HIV viral genes. In light of the potent immune responses seen in previous experiments with adenoviruses, great hope and excitement surrounded the beginning of this test, known as the STEP trial. In all, about 3,000 HIV-negative individuals received the vaccine or a placebo shot.
As the trial progressed, though, a disturbing difference between the two groups began to emerge: people who got the vaccine were no better protected than those who received the placebo, and eventually they appeared to be more vulnerable to being infected by HIV. As a result they found that 49 out of 914 men in the vaccine group became HIV-positive, whereas 33 out of 922 men in the placebo group did. With this realization, in the summer of 2009 the STEP trial was halted.
The STEP trial gives the scientists to look back on the DNA Drugs. To optimize the DNA Drugs effect, the scientist suggest the several steps as visualized on the figured below:
As conclusions, if we fail now is doesn’t means we fails forever. Keep trying and never give up.
No comments:
Post a Comment