Ursinus College
Background AIDS/HIV Information
for Gel Analysis Lab
It is estimated that over a million people in the United States are presently living
with HIV/AIDS and that 40,000 new cases are diagnosed each year. World wide, it is
estimated that there are 40 million cases and 25 million people have died from the disease
since 1981. It is estimated that 1 in 5 people in sub-Saharan Africa are infected with the
HIV virus.
The virus destroys the helper T cells which are specialized white blood cells that
recognize invading organisms. Without these T cells, our bodies are unable to react to
invading disease organisms so while the HIV virus does not kill people directly, it shuts
down the immune response and allows infected people open to a wide range of diseases.
Viruses must send their genetic material into a host cell in order to reproduce.
Most viruses use DNA as their genetic material but HIV is called a retrovirus which
means it uses RNA as its genetic material instead of DNA. Once the viral RNA enters a
host cell, an enzyme allows the RNA to be coded into DNA and that DNA can join with
the host cell DNA. We have vaccines for many viral diseases but scientists have never
been able to make a vaccine for a retrovirus. Although there is no cure for an HIV
infection, there are effective medicines that enable people with HIV to live longer and
healthier lives. Unfortunately, treatment for HIV infection is expensive and requires a
treatment of usually three or four drugs that must be taken exactly as prescribed.
In order to survive and function, cells must communicate with their environment.
One way is through special proteins on the surface of cells called receptors. There are
receptors that react to neurotransmitters, hormones, and chemical messengers warning of
infection. It was found that the HIV when infecting T cells attaches to one of these
receptors called CD-4 but studies indicated that just attaching to this receptor was only
part of the story of how HIV entered cells.
In studying HIV and AIDS, researchers found that while most people are
susceptible to the disease, amazingly, a few people in the world appear to be immune to
the disease. One of them is Steve Crohn, who is a topic of discussion in the introductory
video. They also found some people in whom the disease progressed, but very slowly.
The goal of this lab is to try to explain these unusual cases of resistance.