The human immunodeficiency virus (HIV) is a retrovirus. A retrovirus is a type of virus that has viral RNA in its nucleus instead of DNA. The primary targets of HIV in the human body are T4 or T-helper cells. T4 cells help to organize the immune system’s response against a foreign invader (e.g., virus, bacteria, fungus). HIV attaches itself to T4 cells then inserts its genetic material into the cell. Through various chemically initiated changes, the viral RNA becomes viral DNA and makes its way into the nucleus of the T4 cell. The T4 cell becomes an HIV-producing factory. Eventually, the infected T4 cells die, and their numbers decrease, which leads to a weakening of the immune system. When a person’s T4 cell count drops below 200, which is roughly 70% immune damage, they are diagnosed with acquired immune deficiency syndrome (AIDS).
There are two types of HIV: HIV-1 and HIV-2. HIV-1 is the more common of the two types and is more easily transmitted. HIV is found in all body fluids. However, the quantity of HIV in bodily fluids varies, with blood, semen, and vaginal fluids having the highest concentration of viral particles. Unsafe sexual practices, injection drug use, and transfusions are the main causes of infection. Most people exposed to HIV test positive 2 weeks to 6 months after exposure. Some people changing from HIV negative to HIV positive (called seroconversion) experience viremia or severe flu-like symptoms.
HIV was first identified in 1981. It is believed to be related to simian immunodeficiency virus (SIV). Researchers discovered that chimpanzees were exposed to SIV by eating monkeys. Over a long period of time, chimpanzees became resistant to the disease. Humans are believed to have been exposed to SIV through hunting chimpanzees for bush meat. Because of the 98% comparability of genetic material between humans and chimpanzees, the virus began to infect human beings, a process called zoonosis.
HIV is unique in world history as being one of very few pandemics or worldwide epidemics. It is estimated that up to 46 million people worldwide are infected with HIV. Most infected individuals are adults; however, up to 2.9 million children are estimated to be infected with HIV worldwide. In 2003, 3 million adults and children died from AIDS.
Drugs have been developed that can keep levels of HIV in the blood very low. Persons infected with HIV must take combinations of two or more antiretroviral drugs, also called highly affective antiretroviral treatment (HAART). There are three broad classes of antiretroviral drugs, which attack HIV at various stages in its life cycle. Currently, 22 drugs are approved to treat HIV, with many more being researched. However, there is no cure for HIV. In people with AIDS and those who have sustained damage to their immune system, antiretroviral drugs keep viral levels low, but researchers continue to search for ways to rebuild the immune system.
Researchers are hopeful that a vaccine for HIV will be found. Until a successful vaccine is developed, behavior change remains the key method of preventing new HIV infections. Despite prevention efforts, 5 million new cases of HIV were reported in 2003. Also of concern are the millions of orphaned children in Africa from AIDS, and the growing number of people infected with HIV in Asia and other parts of the world. Finally, many countries cannot afford the drugs to treat HIV. Therefore, getting antiretroviral medications to developing nations will be a key focus for the world.
References:
- AIDS Information. (2003). HIV treatment guidelines.Retrieved from http://www.aidsinfo.nih.gov/drugs
- Centers for Disease Control and Prev (2003). HIV/AIDS surveillance reports. Retrieved from http://www.cdc.gov
- Papathanasopoulos, A., Hunt. G. M., & Tiemessen, C. T.(2003). Evolution and diversity of HIV-1 in Africa: Areview. Virus Genes, 26, 151–163.
- Stratov, , DeRose, R., Purcell, D. F., & Kent, S. J. (2004).Vaccines and vaccine strategies against HIV. Current Drug Targets, 5, 71–88.
- UN (2003). AIDS epidemic update. Retrieved from http://www.unaids.org