Acquired Immune Deficiency Syndrome (AIDS), a destruction of the immune system resulting from infection with the human immunodeficiency virus (HIV). HIV was first isolated in 1983 in Los-Angelus by ______________ first known as ‘Gay Cancer’ because it was most commonly found in homosexual males was about to become one of the worlds most deadly and most familiar sexually transmitted disease. It was to become general knowledge that HIV could be transmitted by several different types of sex between Homosexual and Heterosexual couples. In the early 90’s over twelve thousand cases of AIDS were recorded this was only the start of the world epidemic, which has now reached as staggering 47 million cases world wide.
Human Immunodeficiency Virus (HIV), member of the Retroviridae family of viruses (commonly known as retroviruses), and classified in the subfamily lentiviruses. These viruses have several common features: a long incubation period before disease onset, infection of blood cells and the nervous system, and an association with immune suppression. Retroviruses are classified by their unique feature, the need to convert their genomic RNA into DNA (the process of reverse transcription) using an enzyme that they carry (reverse transcriptase). Human infection with HIV results in a complex clinical disease known as acquired immune deficiency syndrome (AIDS) that may take ten years or more to develop. The outer surface of HIV is a lipid “envelope” derived from the cell membrane. Protruding from the surface are the viral transmembrane glycoprotein (gp41) and the envelope glycoprotein (gp120) that allow HIV to bind and fuse with a target cell. Within the envelope, the viral core protein, (p17), forms the matrix of the virion particle and the core protein, (p24), forms an inner cylindrically shaped nucleoid. The nucleoid contains two strands of viral genomic RNA (the genetic material of HIV) and the associated reverse transcriptase enzyme. HIV will infect cells bearing the surface CD4 molecule (a normal immune protein that HIV uses as its receptor). The viral gp120 specifically recognizes and binds to CD4, leading to the fusion of the virus with the cell membrane. Fusion permits the viral nucleoid to enter the cell. Reverse transcription then occurs to convert the viral genomic RNA into double-stranded DNA. The viral DNA is transported to the cell nucleus and is integrated, or inserted, into the normal cellular chromosomal DNA. When the right activation signals are present, the process of making new virions begins. Using the replication machinery of the host cell, the integrated viral DNA is transcribed to make messenger RNA (mRNA) and new strands of viral genomic RNA. The viral mRNA is then translated into new viral proteins and assembly of new virions takes place within the cell. The new HIV particles are released by budding from the cell surface, taking a piece of the cell membrane as their envelope. HIV replication can directly kill CD4 T-lymphocytes (a type of white blood cell). The loss of these cells paralyses the immune system and is one mechanism by which HIV infection causes AIDS. With the loss of immune function, a clinical syndrome (a group of various illnesses that together characterize a disease) occurs over time and result in death due to opportunistic infections or cancers. In HIV-infected individuals, there is a gradual loss of immune cells (called CD4 T-lymphocytes) and immune function so that the patient becomes vulnerable to pneumonia, fungal infections, and other common ailments.
