The 2008 Nobel Prize in Physiology or Medicine was divided between Harald zur Hausen, who determined that the Human Papillomavirus (HPV) causes cancer, and Françoise Barré-Sinoussi and Luc Montagnier, who discovered the Human Immunodeficiency Virus (HIV). Barré-Sinoussi and Montagnier, virologists, discovered the virus in the 1980s by analyzing lymph node tissue at the Pasteur Institute in Paris. HIV is now well-known as the precursor to Acquired Immunodeficiency Syndrome (AIDS).
What Is HIV?
HIV is a retrovirus, or a virus composed of RNA (rather than DNA). It spreads by reverse transcription: the RNA is incorporated into the host cell’s DNA, which permanently hosts the viral genetic code. HIV is a type of retrovirus called a lentivirus. These are distinguised from other retroviruses by the delay between contraction and symptom display. A person infected with HIV could take years to show symtoms.
HIV Contraction and Mechanics
HIV is best known as a sexually transmitted disease (STD). Unlike other STDs, like the Human Papillomavirus (HPV), HIV cannot be transmitted through genital contact alone: a transfer of semen, vaginal fluid, or pre-ejaculate is necessary for the virus to spread. But, HIV is not just an STD — it can also be transferred through bodily fluids like blood and breast milk. (For this reason, it is dangerous to share needles.)
HIV viruses stay alive by leaching onto CD4+T lymphocytes, white blood cells, that normally attack bacteria and other foreign organisms. To reproduce, HIV enters these white blood cells, inserts its own genetic material into their DNA, and makes copies of itself. In the process, it destroys the white blood cells, which become shells that no longer function to promote the immunity of their human host.
Symptoms of HIV
HIV’s first symptoms, which present six weeks to three months after infection, resemble those of the flu: aches, fever, and rashes. Since HIV functions by attacking white blood cells, as time passes and the virus invades more cells, immunity grows increasingly poor. Diseases that a person without HIV could fight easily become major problems. Symptoms expand to included yeast infections, night sweats, bruising, lesions, weight loss, and diarrhea.
When Does HIV Become AIDS?
The difference between HIV and AIDS is not definitional, it is a matter of degree. In 1993, the Centers for Disease Control and Prevention (CDC) defined the threshold by the number of remaining CD4+T cells. When these lymphocytes — which normally number 800 to 1,200 — drop to 200 or fewer in a person infected with HIV, the disease is defined as AIDS.