HIV is a disease that is caused by the Human Immunodeficiency Virus. Like other viruses, it hijacks the machinery in our own bodies so that it can make copies of itself. HIV specifically targets our immune system, our body’s natural defence system. People with HIV can develop AIDS (acquired immunodeficiency syndrome) which causes their immune system to shut down completely. This is really dangerous because even simple things like the common cold can kill them.
Luckily today there are treatments available that help manage the effects of the infection and stops it developing into AIDS. In fact, there was a study published recently (see here) that showed that HIV patients now have life expectancies close to that of an average person who doesn’t have the infection.
This isn’t the end of the line for HIV research though. Many of these treatments aren’t available in the poorer countries that need them most. Also, these treatments can produce some unpleasant side effects that patients have to deal with every day of their lives. The long-term goal is to find a vaccine that makes us completely immune to the virus. As we will see below, this is easier said than done.
HIV Life Cycle
The HIV particle is coated in a protein called Env which interacts with a protein of the surface of human cells called CD4. This interaction causes the virus particle to fuse with the human cell. All the viral DNA and proteins then spill into the human cell. The DNA has all then instructions needed to make more of the virus and the virus hijacks the human cell machinery so that it can make copies of itself. Once enough new viruses have been made, they get released from the human cell and they go out in search for another target.
Sugars in HIV Infection
So how are sugars involved in this life cycle? Well the Env protein that coats the HIV particle is a glycoprotein (meaning that it has sugars attached to it. See here.). Sugars from foreign objects normally help show them as foreign and our immune system kicks in to try to get rid of them. The problem with HIV, and other viruses, is that it hijacks our own machinery to copy itself. This means that all the sugars on the Env protein are actually human sugars! Our immune system doesn’t recognise the HIV particle as foreign and so just ignores it.
One line of current research involves making molecules that look like these Env protein sugars. The hope is that these artificial sugars will trigger the immune system against them, but they will also train the immune system to recognise the Env protein sugars. Only time will tell whether this approach will be effective, but the future is certainly looking brighter for those who are suffering from HIV.