HIV-AIDS

-AIDS is causd by Human Immunodeficiency Virus(HIV) which attacks helper T lymphocytes or macropahges.
-It causes reduction in number of lymphocytes and macrophage causing loss of immunity.
-HIV is a retrovirus which contains 2 molecules of RNA as carrier of genetic material, surrounded by 2 layers of globular proteins and outermost lipoprotein layer.
-HIV also contains reverse transcriptase enzyme which converts RNA to DNA in cytoplasm of infected cell and integrase which integrates HIV DNA into host cell DNA.
-HIV survives in body fluids such as blood and seminal fluid.

Mechanism of Transmission:
-Sexual intercouse-seminal fluid, vagina fluid, from person to person.
-Blood-passes HIV particles or infected lymphocytes
.sharing of contaminated needle-drug addicts.
.contaminatred blood-through blood received by blood transfusion.
.wound to wound.
-Mother to foetus-through placenta ad mother's milk.

Symptoms:
-First sign-attack of cold-revoer in few days.
-Next 6 years-no signs of disease, then rapid loss of weight.
-Fever and sweating at night.
-Diarrhoea, tiredness.
-Oppurtunistic disease-cough, infection in mouth and sexual organs and Kaposi Sarcoma infect patient-soon patient dies.

Prevention:
-Protection during sexual intercouse-condom
-Limiting 1 sexual partner.
-Avoid sharing injection needle.
-Donated blood-screening for HIV to ensure HIV Free.
-Educate public on mode of transmision.

Mechanism of HIV infection:
-HIV binds to cd4 receptors at the surface of Th lymphocyte.
-Endocytosis-lipoprotein of lymphocyte and HIV fuse.
-Viral RNA and reverse transcriptase enzyme enter lymphocyte.
-Reverse Transcription of RNA into single strand DNA by reverse transcriptase enzyme occurs.
-Reverse Transcription of the other RNA produces single strand DNA that is complementary the other single strand DNA produced.
-The 2 single strand DNA are bind to form viral DNA known as provirus.
-Provirus enters nuclues and incorporated into DNA of the host cell.
-Each time host DNA replicates, provirus replicates.
-Provirus stays dormant for about 6 years.
-Then transcription of provirus occurs forming mRNA.
-mRNA produced is then translated to synthesis viral proteins.
-Viral particles formed in the infected cells.
-Through lysis of T lymphocytes, HIV virus is liberated.
-Virus spreads to all Th cell, killing the T cells-lower amount of T cells then destroy infected persons immune system.
-Oppurtunistic disease such as Kaposi Sarcoma occurs.