Normally, white blood cells and antibodies attack and destroy foreign organisms that enter your body. This response is coordinated by white blood cells known as CD4 lymphocytes. These lymphocytes are also the main targets of HIV, which attaches to the cells and then enters them. Once inside, the virus inserts its own genetic material into the lymphocytes and makes copies of itself. When the new copies of the virus break out of the host cells and enter the bloodstream, they search for other cells to attack. In the meantime, the old host cells and some uninfected CD4 cells die from the effects of the virus. The cycle repeats itself again and again. In the process, billions of new HIV particles are produced every day. Eventually, the number of CD4 cells in the body decreases, leading to severe immune deficiency, which means your body can no longer effectively fight off viruses and bacteria that cause disease. HIV can be transmitted by Sexual Intercourse, Transfusion if infected blood, Child Birth, Sharing of needles or accidental needle prick.