Human Immunodeficiency Virus (HIV)
The first recorded case of HIV was recorded in 1959. With no medical intervention HIV can result in death
within 10 years. If caught early with current medicine HIV positive people generally live an average life
expectancy.
Early symptoms of HIV infection range widely. Some may experience no symptoms; others may feel like
they have a bad flu 2-4 weeks after infection. People may develop a bad fever, sore throat, rash, and feel
sore and tired. During this phase the virus is replicating and spreading through the body infecting cells.
The HIV virus specifically targets and replicated in immune cells and people’s immune system may be
weak during this phase.
HIV has a latency phase during which it does not cause any symptoms. This may last up to 10 years in
untreated patients. In treated patients this phase can last for the rest of their life.
The final stage of the HIV virus is called AIDS. The immune system begins to shut down and patients are
susceptible to infection from other diseases. Often AIDS patients will ultimately die of pneumonia or
another disease that would be fought off by the immune system of a healthy individual. With no treatment
this phase generally lasts 3 years. HIV positive people with treatment often do not enter the AIDS stage
and have a normal life expectancy.
HIV undergoes a cycle known as the lysogenic cycle within the body. The first step of this cycle is to find
an immune cell and attach to it with special antigens found on the envelope. This step is called
attachment. Once the virus has attached to a cell it’s next step is injection. The virus injects its RNA into
the cell. The enzymes injected by the virus change the RNA to DNA which is then inserted into the host
DNA in a step called integration. Now whenever the DNA of a cell is replicated and new cells are formed
they have the genetic code for the HIV virus within their own DNA. During this phase a patient usually will
not experience symptoms as the virus is not killing cells. If a person progresses to AIDS the viral DNA
undergoes excision where the viral DNA is cut out of the DNA of the host cell. The virus then begins
replication where it takes over the host cell's machinery and begins to copy its genetic code and the
proteins to create the capsid, enzymes and antigens. All of these pieces come together during assembly
as the viruses form. Eventually the cell undergoes lysis when there are too many viruses for the cell to
hold. From here the virus enters the lytic cycle where it attaches to other cells and immediately replicates
without inserting itself into the DNA of the host cell. Some viruses only undergo the lytic cycle, such as
the Ebolavirus. These viruses cause disease much more quickly than those that undergo the lysogenic
cycle.