Gene therapy has bee, by A. Centers

Gene therapy has been a buzzword for many years now. There have been some stunning successes and glaring failures, sometimes with frightening results. However, with a growing understanding of the human genome and some tantalizing successes, gene therapy continues to be pursued.
Occasionally, some genes are expressed at reduced levels or, maybe not at all. Depending on what gene is involved, this may go unnoticed or it could even be life threatening. In short, gene therapy is an attempt to overcome these shortcomings by inserting one or more properly functioning copies of that gene into a patient. Alternatively, a gene may be inserted that augments an existing function or even adds a new one. This has been VIRxSYS approach to HIV gene therapy.
But first a little biology: The life cycle of HIV requires that it infect lymphocytes, or white blood cells, after entering a host, resulting in reduced numbers of these cells. This is very unfortunate because lymphocytes play a huge role in both our innate and adaptive immune systems. The innate system is made up of many types of cells that continuously search for and directly attack foreign material, bacteria, viruses, etc. The adaptive system is also in constant surveillance for anything foreign. However, once something foreign, the measles virus for example, enters our body and is identified as such, the adaptive immune system begins producing antibodies.
Antibodies are made by T cells, and are incredibly picky about what they interact with. The antibodies from the example above would recognize and bind only the measles virus, nothing else. Once bound by antibodies, the virus is targeted for destruction by other components of our immune system. Production of antibodies is a lifelong commitment for T cells. Once a group of T cells begins production of a specific antibody, they become dedicated factories for producing only that antibody. Such subpopulations of T cells retain the ability to recognize the same virus if it were to re-infect us sometime in the future. Antibody production would begin immediately. This is where the name “memory T cells” originates. This is also why you get the measles only once. Any parent of school age children has been exposed numerous times to measles, but thanks to you memory T cells, the immune response was instant and therefore effective.
T cells regularly die off and the antibodies they produced slowly degrade. If all T cells of a given subpopulation died off we would lose the ability to mount a rapid antibody mediated immune response. You would measles over and over! To safe guard against this, some T cells of each subpopulation go dormant. Once re-exposed to the same foreign material, say, the same virus as in the example above, memory T cells begin antibody production anew.
I apologize for the biology lesson above but the role of T cells in HIV is a big one, one perhaps more evident now that the above passage explains why we have dormant T cells. You see, the unfortunate thing is that HIV likes to replicate in them. When these cells go dormant they are in fact allowing HIV particles to hide from our immune system and drug treatments. This allows HIV to continually reestablish an infection in the host for years (a theory but one that makes sense and has many supporters). Here is part of the problem with highly active antiretroviral therapy or HAART. While HAART can be initially effective at reducing HIV viral loads, it would have to continue uninterrupted for life to completely get rid of all HIV particles. Even without the emergence of drug resistant HIV strains, this scenario is just not a good option.
Here is where the gene therapy comes in. Virxsys is attempting to introduce a gene into HIV patients that changes the surface of T cells, specifically, a single protein. This single protein recognizes HIV, potentially boosting the ability of T cells to bind HIV. Virxsys believes this will translate into a faster stronger anti-HIV immune response. In a bit of irony, Virxsys is using another retrovirus, a lentivirus, to accomplish this. As you may be aware, retroviruses are RNA viruses, carrying with them the machinery and proteins to copy their genome into DNA and then integrate their DNA into that of the host cell. Now, the cell will unwittingly read host and viral genes, manufacturing the proteins called for by both. This process goes on constantly, leading to production of more and more viral particles. Lentiviruses pose no threat to humans, incorporate very well into our DNA, and grow very slowly. All of this means lentiviruses can effectively deliver their anti HIV payload inside us for a very long time.
This is not the only gene therapy Virxsys is pursuing. In our cells, a hugely complex group of proteins read our DNA and in a very complex series of steps make new proteins. As long as everything in our DNA is coded properly, the correct proteins are made. However, if our DNA contained garbled portions, the above mentioned machinery would struggle to make proteins. Depending on how seriously garbled the DNA message was, the resulting protein would not function properly or might not be made at all. Virxsys is attempting to do this on purpose. Using lentiviruses again, Virxsys is attempting to insert into HIV patients a garbled version of a gene unique to HIV. This garbled gene would produce malfunctioning copies of a crucial structural component, without which HIV cannot survive. Theoretically this could result in production of a huge number of noninfectious HIV particles. Potentially, this drops the number of infectious HIV particles to a level low enough the infection can no longer be maintained.
These approaches are not a cure – yet! Early results are promising, but only time will tell how ultimately successful these treatments can be.

About Friar Timothy, Franciscan Urban Mission, INC.

Disciple of Jesus Christ with a Progressive Message, Author, Franciscan Friar, Musician, Social Activist, and Urban Missionary View all posts by Friar Timothy, Franciscan Urban Mission, INC.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: