Question

writing a biology essay on HIV/AIDS topic

Answer 1

Human immunodeficiency virus infection and acquired immuno defficiency syndrom is a condition caused by infection of Human immunodeficiency Virus (HIV). Usually spread by unprotected sex, contaminated blood transfusions, hypodermic needles, mother to child during pregnancy. Body fluids like saliva and tears do not transmit HIV.

Signs and symptoms:

Individuals infected with HIV develops influenza like illness or a mononucleosis like illness, 2-4 weeks post infection. Symptoms occur in 40-90 % cases. Mild fever, large tender lymph nodesw, throat inflammatuon, rashes, headache, sores of mouth and genitals are also few of the symptoms.

AIDS is defined in terms of CD4+ cell count below 200 cells per microlitre of occurance of specific disease in association with HIV infection. In absence of treatment post infection half of the people infected with HIV develop AIDS in about 10 years.

Pneumosystis pneumonia, cachexia, esophageal condidiasis, respiratory tract infections are some of the signs of AIDS. Opportunistic infections caused by bacteria, fungi and viruses may also occur due to reduced immunity in the patients.

HIV life cycle:

1. Binding: HIV binds to receptors on surface of CD4 cells.
2. Fusion: HIV envelops and CD4 cell membrane fuses, which allows HIV to enter the CD4 cells.
3. Reverse transcription: Inside CD4 cells, HIV releases reverse transcriptase and use them to convert its genetic material, HIV RNA, into HIV DNA. This allows HIV to enter CD4 cell nucleus and combine with cells DNA.
4. Integration: inside CD4 nucleus, HIV release integrase and uses this to insert its viral DNA into host cell DNA.
5. Replication: Once integrated into host cell DNA, HIV uses machinery of the cell to synthesis long chains of HIV proteins. These acts as building blocks for more HIVs.
6. Assembly: Now HIV proteins and RNA move to surface of cell and assemble into immature HIV.
7. Budding: The immature HIV oushes itself out of the host cell. The new HIV releases proteases that break up the long chains of HIV protein. These smaller chains then combine to form mature HIV. Which further attacks more of the CD4 cells.

After the HIV utilises the CD4 cells machinery for its multiplication, it brings about cell programmed death or apoptosis of theses host cells. Thus affecting the immunity of the patient.