Expert: Walter Hintz - 10/14/2005

Question
HI..  it has been 20 years now since the appearence of the hiv virus. As a reference to polio, chickenpox etc, why is there no vaccine yet for hiv. What made it possible to manufacture a vaccine for polio? I have been to the tropics and there is a virus menace there in the form of dengue fever carried by a mosquito. I am sure you know that this disease has been existing for ages and yet there is no vaccine. I do not understand the mechanism of all this. Your eloborate answer will be a joy to me as Biology has been a great interest of mine since childhood.

regards
roy

Answer
Although I am not an immunologist roy I believe that it has to do with the nature of the virus particle.  All viruses are not alike.  Think about the common cold virus. The cold has been around longer than perhaps any other virus and there is no vaccine for that either.There are many different virus particles that cause the common cold. The problem lies in the ability of a virus to change its protein coat.  Once a virus has been tagged and antibodies formed against it it changes.  About the only success when it comes to vaccines against the virus is with the flu virus and even then it is necessary to constantly change the vaccine. Even then the flu shot sometimes is not effective.
 I have heard that there is some progress in developing a vaccine against HIV but so far only drug treatments have been able to supress it.