HIV belongs to a class of viruses known as retroviruses. Retroviruses use RNA to encode their genetic information rather than DNA, as human cells do. What distinguishes retroviruses from other classes of viruses is that during their replication cycle inside cells, they use a special enzyme called reverse transcriptase to convert the RNA into DNA.
HIV PROCESS
HIV must enter into a cell before it can replicate or make more copies of itself. There are a defined number of steps that the virus goes through to make more copies of itself. These steps require the action not only of virus proteins but also proteins within the cell that the virus “hijacks” for its own purposes.
- BINDING &FUSION To begin an infection, the HIV particle must encounter and bind to the CD4 receptor that is present on the surface of a subset of T cells (and also some other immune system cells called macrophages, but not on most other cells in the body). The interaction between HIV and the CD4 molecule, along with another molecule called a co-receptor, allows HIV to enter the cell.
- REVERSE TRANSCRIPTION The virus enzyme reverse transcriptase then converts the RNA to DNA.
- INTEGRATIONAnother viral enzyme called integrase inserts the virus’ DNA into the cell’s DNA in a step known as integration.
- TRANSCRIPTION Next, the cellular machinery, with the help of virus protein named Tat, makes many RNA copies of the virus in a process called transcription.
- ASSEMBLYThe RNA copies are then used to make virus proteins, and the RNA copies and virus proteins are assembled into new virus particles.
- RELEASE The long chains of virus proteins in the virus particle have to be cut into smaller pieces by another viral enzyme called protease. The new HIV particles are released from the cell by a process called budding and then can go on to repeat the cycle and infect more and more CD4+ T cells.
(important steps in the replication of HIV)
Scientists have spent many years trying to understand the details of these steps, because these steps represent possible targets for drug intervention. Because each of these steps is required for the virus to produce more copies of itself, blocking these steps should prevent the virus from continuing to replicate. Until recently, anti-HIV drugs were available that block three different steps in the HIV replication cycle - the entry of the virus into the cell, the reverse transcription step that converts RNA to DNA, and the protease step which is needed to produce the right forms of the virus proteins (see diagram). In the fall of 2007, a drug that blocks another step in the virus replication cycle was approved. The new drug inhibits the integrase enzyme that is necessary for the virus to insert itself into the host cell genome. It is most effective to use a combination of drugs that blocks multiple steps in the HIV replication cycle, a treatment regimen called HAART (highly active antiretroviral therapy).
references:-
https://www.bcm.edu/molvir/hivaids
https://www.bcm.edu/cms_web/78//images/eidbd/hiv-life-cycle.jpg
video :_
http://www.youtube.com/results?search_query=hiv+life+cycle&oq=hiv+life+cycle&gs_l=youtube-reduced
physical changes to body :-http://aids.gov/hiv-aids-basics/just-diagnosed-with-hiv-aids/hiv-in-your-body/physical-changes/index.html
 BODY FAT CHANGES : Some medications you may take to control HIV cause changes in the way your body produces, uses, and stores fat. These changes are called lipodystrophy. This condition causes you to gain or lose fat in particular parts of your body. You can get extra fat in the following places:
Other changes can occur when the fat under your skin (called subcutaneous fat) is lost. This can occur in your:
It is important to note that these changes in the way your body handles fat can also coincide with changes in cholesterol, an increase in triglycerides, increases in blood sugar, and lowered sensitivity to insulin, which may lead to diabetes. WASTING SYNDROME :- Wasting syndrome is the involuntary loss of more than 10% of your body weight, in addition to more than 30 days of either diarrhea or weakness and fever. Wasting refers to a loss of muscle mass, although part of the weight loss may also be due to loss of fat. HIV-associated wasting syndrome is considered an AIDS-defining condition. While this is often a sign of late stage disease, wasting syndrome can be treated by:
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