Human immunodeficiency virus (HIV) is a lentivirus (slowly-replicating retrovirus) that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive (1). A virus is a piece of genetic material, RNA or DNA, surrounded by a protein coat. To replicate, a virus must infect a cell and direct its cellular machinery to produce new viruses. A virus cannot reproduce without infecting a cell.
Viruses prey upon all living organisms, turning them into virus Xerox machines. Unlike a bacterium or a cell of an animal, a virus lacks the ability to replicate on its own. A virus does contain some genetic information critical for making copies of it-self, but it can’t get the job done without the help of a cell’s duplicating equipment, borrowing enzymes and other molecules to concoct more virus. HIV is a RNA virus, which means the virus instructions are stored in strands of RNA – not in strands of DNA.
A RNA virus is a Retrovirus. In order for the virus to take over the cell, it must copy the RNA instructions into DNA instructions (own words out of Microbiology book) Lentivirus (lente-, Latin for “slow”) is a genus of viruses of the Retroviridae family, characterized by a long incubation period. Lentiviruses can deliver a significant amount of viral RNA into the DNA of the host cell and have the unique ability among retroviruses of being able to infect non-dividing cells.
(2) AIDS (Acquired Immune Deficiency Syndrome) refers to any number of severe physical manifestations resulting from HIV infection. H – Human: because this virus can only infect human beings. I – Immune-deficiency: because the effect of the virus is to create a deficiency, a failure to work properly, within the body’s immune system. V – Virus: because this organism is a virus, which means one of its characteristics is that it is incapable of reproducing by itself. It reproduces by taking over the machinery of the human cell.
A – Acquired: because it’s a condition one must acquire or get infected with; not something transmitted through the genes I – Immune: because it affects the body’s immune system, the part of the body which usually works to fight off germs such as bacteria and viruses D – Deficiency: because it makes the immune system deficient (makes it not work properly) S – Syndrome: because someone with AIDS may experience a wide range of different diseases and opportunistic infections.
In the early stages, an HIV positive person looks and feels perfectly healthy and is able to continue with all normal day to day functions. Over a period of time (4-8 years on average) as the virus starts multiplying in the body, the immune system becomes weak and the body becomes susceptible to various diseases. That is the time when the person is said to have AIDS. Clinically, a person is said to have AIDS when they have HIV and another infection, called an “opportunistic infection” and/or their crucial immune cell (CD4+) count falls below 200cu/mm.
As a result, AIDS is a condition caused by HIV. (Research Paper Florida Hospital of Altamonte Springs about AIDS). Symptoms of AIDS: Primary HIV Infection A person may be infected with HIV but not know it, because many people who are infected do not have any symptoms for several years after getting infected. Primary HIV infection refers to the very early stages of HIV infection, or the interval from initial infection to the time that antibody to HIV is detectable.
During this stage of HIV infection, patients typically have some symptoms of acute HIV seroconversion illness, very high HIV RNA levels of >100,000 copies/mL, and negative or indeterminate HIV antibody tests. The diagnosis of patients with primary HIV infection is a clinical challenge because the symptoms of primary HIV are often absent, mild, or nonspecific. After infection with HIV, it takes a median of 25 days before the HIV antibody test becomes positive; in some individuals, it may be several months before seroconversion.
About half of patients who become infected with HIV develop symptoms consistent with primary HIV infection. Symptoms typically appear a few days to a few weeks after exposure to HIV, and generally include several of the following: • Fever • Rash, often erythematous and maculopapular • Fatigue • Sore throat • Lymphadenopathy • Urticarial • Myalgia/arthralgia • Anorexia • Mucocutaneous ulceration • Headache, retro-orbital pain • Neurologic symptoms (e. g. , pain, numbness, loss of motor function) This symptomatic phase usually persists for 2-4 weeks or less, although lymphadenopathy may last longer.
These symptoms and signs are similar to those of many other illnesses, including other viral syndromes, such as “flu” and “colds”. To diagnose early HIV infection, clinicians must consider HIV in the differential diagnosis for at-risk patients with symptoms resembling flu or mononucleosis. A history of recent risk behaviors should be obtained from all patients who present with symptoms consistent with acute HIV infection. Advanced HIV Infection After the period of primary infection, an individual may live for several years to decades before experiencing new symptoms.
During this period, the virus attacks the person’s immune system, and over time an individual may experience the following symptoms that may indicate advanced HIV infection: • Rapid weight loss and loss of appetite • Dry or productive cough • Recurring fever or profuse night sweats • Profound and unexplained fatigue • Swollen lymph glands in the armpits, groin, or neck • Diarrhea that lasts for more than a week • White spots or unusual blemishes on the tongue, in the mouth, or in the throat • Shortness of breath • Red, brown, pink, or purplish blotches on or under the skin or inside the mouth,
nose, or eyelids • Memory loss, depression, and other neurological disorders After an individual’s immune system experiences significant damage from HIV infection, the person may progress to Acquire Immune Deficiency Syndrome (AIDS), a condition that is characterized by low CD4+ cells (below 200 cells/mL or below 14% of total lymphocytes) and/or one or more AIDS-defining clinical conditions, or Opportunistic Diseases (OD ). (3) The Biology of HIV [pic]www. google. com/Biology of HIV Basic HIV Biology: HIV, as with all viruses, cannot replicate on its own; it needs a host cell.
The virus enters the cell and converts the machinery of the cell into a factory that reproduces the HIV. HIV is a retro-virus which means that its genome is 2 RNA strands (not DNA like most other living organisms). An enzyme called reverse transcriptase turns the host cells DNA into RNA in order for the virus to fully infiltrate the host cell. Once this happens, the HIV DNA is integrated into the host cell DNA and the host cell starts producing HIV proteins. Thus allowing the HIV to take over, kill the cell, and further multiply.
When HIV enters the body, it targets lymphocytes, a type of white blood cells which usually fight off infections. On the surface of the lymphocytes (specifically the CD4+ lymphocytes) are different types of studded protein molecules such as CCR5. HIV acts like Velcro, binding itself to the studded protein molecules, using the protein’s surface as the corresponding side of the Velcro. On the spherical HIV, there are stalks and on the end of each stalk there are clumps of molecules called gp120. Essentially, the virus looks like a plastic ball covered with suction cups.
Once inside, the HIV commandeers the cell’s DNA and begins to copy itself. The new copies burst out of the cell. In the process, the cell is destroyed. The new copies are free in the body looking for new cells to invade. Billions of CD4+ cells are hijacked and destroyed each day, rapidly multiplying into billions of new HIV viruses. Within days of infection, millions of copies of the HIV have made its way into the lymph nodes and can hide there for many years before reappearing. A person infected with HIV rarely shows symptoms initially.
It is—at this point—before the start of an immune response, that the person is probably most infectious. A few weeks after infection, the body produces killer T cells in response. This stage is called the “seroconversion” stage. The killer T Cells drive the virus back, but cannot eliminate it. Rapid mutations of the virus hinders the killer T’s ability to recognize the virus. The production of killer T cells can cause a person to feel flu-like symptoms. Antibodies (Y-shaped molecules with mitten-like protrusions) latch onto and kill infected cells and microbes.
Lymphocytes and antibodies clear most of the virus particles, but some viruses escape by mutating. The body must constantly adapt a new immune system response to tackle the constant mutations. HIV is a highly variable virus that mutates very easily in the human body to outsmart the immune system. This means there are many different strains of HIV, even within the body of a single HIV positive person. Based on genetic similarities, the numerous virus strains may be classified into types, groups and subtypes.
HIV-1 and HIV-2 are the most common types of HIV. The HIV virus begins a slow war on the immune system. As CD4+ cells die, the immune system becomes increasingly impaired. A person is said to be diagnosed with AIDS when they have a positive HIV test and their CD4+ cell count is less than 200/cubic millimeters (cu. mm); AND/OR they have a positive HIV test and an opportunistic infection. A healthy, uninfected person usually has 800 to 1,200 CD4+ cells per cu. mm of blood. (4) The progression of HIV to AIDS may range anywhere from 1 to 10 years, or longer.