There is no doubt that AIDS is indeed the epidemic of the decade. Not only are there many supporting facts and data, visiting urban cities and third world countries prove this point. Furthermore, AIDS is not only highly infectious, it is also the first major incurable epidemic throughout this biomedical revolution that mankind is going through. This epidemic might actually be the one that will completely wipeout the third world. Scientists, government agencies and pharmaceutical companies are scrambling to find a cure to this epidemic but in the mean time we have to find a way to deal with it, if possible.
As we continue into the next millennium with all sorts of problems facing humanity, the choice with regard to AIDS is simple, evolve or die! The Human Immunodeficiency Virus (HIV) has two different types of strains. HIV-1 is the North American strain while HIV-2 is the African strain. The only real difference between the two is that HIV-2 has the vpx gene while HIV-1 does not. As you can tell by the name, the virus works by gradually deteriorating the immune system. The virus can infect any cell with CD4 molecules on the cell’s membrane. It seems to specifically destroy or disable the CD4+ T cells.
These cells are sometimes called “T helper” cells. They work by signalling other cells to perform their special functions. A normal healthy person usually has a CD4+ T cell count of 800 to 1,200 per cubic millimetre of blood. Once a person’s CD4+ T cell count falls below 200/mm3, a person is diagnosed with Acquired Immunodeficiency Syndrome (AIDS). A person diagnosed with AIDS will usually die of an opportunistic infection, not of HIV/AIDS itself. HIV is a virus and a virus is basically a microscopic bag of protein filled with a strain of DNA or RNA.
To be more specific, HIV has a diameter of approximately 1/10,000 of a millimetre and is spherical in shape (see Figure 1-1). The viral envelope consists of two layers of lipid molecules and contains proteins taken from the host cell. There are 72 copies (on average) of a complex HIV protein called Env. Env is made of three or four molecules of a glycoprotein, gp120, that form a cap and a stem consisting of gp41 molecules that anchor the structure to the surface of the viral envelope. HIV belongs to the class of viruses known as retroviruses. HIV is a retrovirus because its viral core is composed of RNA.
Inside the viral core there is a capsid that is made of 2000 copies of a viral protein called p24. This capsid surrounds two strands of HIV RNA, each of which contains nine of the virus’ genes. Three of these genes (gag, pol, and env) contain information regarding the manufacture of structural proteins and new virus particles. Three regulatory genes (tat, rev, and nef) and three auxiliary genes (vif, vpr and vpu) contain information regarding the production of proteins that allows HIV to infect a cell, produce new copies of the virus or cause disease.
At the end of the HIV RNA strands there is a RNA sequence called long terminal repeat (LTR). The LTR acts as a switch to control the production of new viruses. Proteins from the virus or the host cell trigger the LTR. The core of HIV also contains a protein called p7, the nucleocapsid protein and the three enzymes that carry out later steps in the virus’s life cycle: reverse transcriptase, integrase and protease. The p17 protein called the HIV matrix protein, lies between the viral core and the viral envelope.
