AIDS was discovered in the early 1980’s after gay men started developing rare, opportunistic infections that were resistant to any treatments the doctors were providing. At this time, AIDS had not been given a name, but the doctors could clearly see that the men were suffering from the same illness. AIDS (Acquired Immune Deficiency Syndrome) is a medical condition where the infected person(s) immune system is too weak to fight off infections. Since its discovery AIDS has been a global epidemic, with an estimated 33.
3 million infected people living with HIV and AIDS. HIV (Human Immunodeficiency Virus) was discovered soon after. HIV is a virus that attacks a person’s immune system cells. As the cells get progressively more damaged by the HIV, the body becomes more susceptible to infections which it will have very little success at fighting off. At this stage of HIV, the very late stage, the person is known to have AIDS. HIV is a lentivirus; this is a specific virus in that it attacks only the immune system. Lentiviruses belong to a larger group called the retrovirus.
The term ‘lentivirus’ means ‘slow virus’ because they take such a long time to produce any symptoms within the body. They have been found in several different animals, the most interesting lentivirus is the SIV (Simian Immunodeficiency Virus) that affects monkeys. SIV is believed to have been around for at least 32,000 years. This is where researchers believe HIV started, SIV transferred from two different types of primates until it reached the chimpanzees, which are believed to have given it to humans. Since we are animals ourselves, we were just as susceptible to the virus.
In order for humans to obtain any type of virus from a non-human primate, it would have to be through zoonosis. Zoonosis is a viral transfer between animals and humans. Research shows that HIV bears a very similar resemblance to SIV, so therefore we know that HIV is a descendant of SIV. Running head: AIDS and HIV 3 Two types of HIV have been identified, HIV-1 and HIV-2. The differences between HIV-1 and HIV-2 are that HIV-2 is less easily transmitted and the period between infection and illness is longer. The most popular and common virus is HIV-1.
If you have the HIV-1 infection then you have a decrease in your CD4+ cells and an increased viral load, which is the level of HIV in your blood. There are three different stages of HIV and they can all be determined by measuring the patients CD4+ cells and their viral load. The different stages are called acute infection (primary infection), latency stage, and AIDS. Acute infection only lasts a few weeks after the initial infection and includes symptoms of fever, swollen lymph nodes, sore throat, muscle pain, mouth and esophageal sores.
The latency stage can last anywhere from two weeks from initial infection to twenty years or more. The symptoms of the latency stage involve few to no symptoms at all. AIDS, which is the last stage of HIV infection, is characterized with low CD4+ cells, multiple infections, cancers, and other conditions. Other symptoms of AIDS include: gradual and mysterious weight loss, persistent respiratory tract infections, prostatitis, skin rashes, and mouth sores. When you have AIDS your immune system is almost obsolete, meaning that even the slightest infection that would be otherwise minute, is very deadly.
For examples: the common flu and especially pneumonia. Transmission can occur through blood products, childbirth, and intercourse. The transmission route for blood products can explain HIV infections in drug users that use needle injection (not using clean needles), hemophiliacs, and recipients of blood transfusions. There is also a strong concern of HIV transmission in third world countries where there is a low hygiene quality for the use of injection equipment, and where there is little money to buy the needed Running head: AIDS and HIV 4 amount of needles (reuse is common).
Anyone that comes into contact with needles is at risk for contracting HIV. For example: people receiving tattoos, piercings, and scarification procedures. Doctors and nurses are also at risk where they are in contact with blood more often than the average person; however, they are at a much lower risk. Mother-to-child transmission can occur during pregnancy, during childbirth, or when the mother is breast feeding her child. If the mother goes untreated from the time of infection, the transmission rate during pregnancy and during birth increases by twenty-five percent.
However with the options of antiretroviral drug treatment and cesarian section available (treatment and no blood contact during birth), the transmission rate can be as low as one percent. A majority of HIV infections are obtained through unprotected intercourse. Sexual transmission occurs when the fluids of the infected individual come into contact with any mucous membranes of their partner (oral, genital, anal). In high income countries, the risk of transmission is . 08%-. 04%. However, in low income countries, these rates are 4 to 10 times higher.
HIV is very unique in structure; it has a different shape than all other retroviruses. It is spherical and is approximately sixty times smaller than a red blood cell; however, this is large for a virus. HIV has a very complex structure including two copies of positive single-stranded RNA, contains nine genes that are enclosed by a capsid, which is composed of over 2,000 copies of the HIV viral protein. The virus also includes many enzymes needed for the development of the virion, these include: reverse transcriptase, proteases, ribonuclease, and integrase.
The matrix contains viral protein p17 which surrounds the capsid. This unifies the particle, making Running head: AIDS and HIV 5 sure it stays together. Then the outer viral envelope that contains two layers of fatty acids (phospholipids), which are taken from a human cell. Within the viral envelope are more proteins taken from the host cell along with over 70 copies of the HIV protein. The HIV protein has three molecules called glycoprotein and a stem that holds it in the viral envelope. The glycoprotein allows the virus to attach to target cells; this is what starts the vicious, infectious cycle.
Not only does HIV infect your CD4+ cells, it can also infect your macrophages (big eating cells), and your microglial cells. HIV enters the cells by attaching its glycoproteins to the receptors on the surface of the target cells. Then the virus fuses its viral envelope with the cell membrane of the target cell and releases the HIV capsid into the target cell. The reverse transcriptase process (virus replication) that occurs after the virus enters the cell is very delicate and can have no mistakes.
Any mutations could cause drug resistance and/or can allow the virus to deceive the host’s immune system. Next the virus enters the assembly and release stage. Here, the glycoproteins go through the endoplasmic reticulum and are then transported to the Golgi apparatus, where it is turned into two HIV envelope glycoproteins. The HIV glycoproteins are then taken to the plasma membrane where it starts to bud from the host cell. HIV has a very high genetic variability; this is due to its fast replication cycle and a high mutation rate.
Many HIV positive people are not aware they are infected with the virus, as previously stated, the latency stage can last anywhere from two weeks to twenty years and has little to no symptoms. The symptoms of the primary stage resemble that of the common cold. This means Running head: AIDS and HIV 6 that someone could think they have the common cold and then be in the latency stage for up to twenty years while the virus lays dormant in their body, not knowing they are infected. Testing for HIV-1 consists of screening with an assay (ELISA) that detects antibodies for HIV-1.
If the ELISA comes back as non-reactive you are considered HIV-negative, unless you were exposed to a different partner between the period of testing and the result period. If the ELISA comes back as reactive you are given two more ELISA tests and if either of those comes back as reactive, you are reported as consistently reactive and undergo more specific testing immediately. There is presently no cure for HIV. Treatment consists of antiretroviral therapy (HAART). HAART was introduced in 1996 and is described as highly beneficial to its recipients.
Although HAART is not a cure, it prolongs the intensity of the disease significantly. If therapy is deferred, death rates are twice as high. AIDS advancement is more accelerated and less measurable in kids rather than adults, therefore, a more strenuous treatment is implemented on children. After the initial infection, the average person can survive nine to eleven years without treatment (depending on the type of HIV) and approximately a year after progressing to AIDS. In resource-limited areas, the average survival rate after being diagnosed with AIDS is six to nineteen months.
In more resourceful areas, the death rate is decreased by eighty percent and life expectancy rises to twenty to fifty years from initial infection. AIDS is estimated to have killed approximately twenty-five million people between when it was first recognized in 1981 and 2005. In 2005 alone, the disease took an estimated 2. 8 million lives, over half a million were kids. AIDS is one of the most destructive pandemics ever recorded in history. It is more Running head: AIDS and HIV 7 than likely that we will never know who the first person infected with HIV was or how it initially spread from that person.
Now scientists need to focus not on how the AIDS epidemic started, but how those effected can be treated, how we can keep HIV from being spread further, and how we can prevent a similar pandemic from occurring again.
Running head: AIDS and HIV 1 AIDS and HIV Ashley Cram Southern Maine Community College Nancy Mattsson Microbiology July 25,2011 Running head: AIDS and HIV 8 Bibliography 1. Smith, Johanna A. ; Daniel, Rene (Division of Infectious Diseases, Center for Human Virology, Thomas Jefferson University, Philadelphia) (2006). “Following the path of the virus: the exploitation of host DNA repair mechanisms by retroviruses”.
ACS Chem Biol 1 (4): 217–26. 2. Weiss RA (May 1993). “How does HIV cause AIDS? “. Science 260 (5112): 1273–9. 3. Migueles, S. ; Connors, M. (2010). “Long-term Nonprogressive Disease Among Untreated HIV-Infected Individuals: Clinical Implications of Understanding Immune Control of HIV”. Journal of the American Medical Association 304 (2): 194–201. 4. Levy, J. A. (1993). “HIV pathogenesis and long-term survival”. AIDS 7 (11): 1401–10. 5. Cochrane Systematic Review on interventions for prevention of late postnatal mother-to-child transmission of HIV.