HIV by liwenting


									Human Immunodeficiency Virus-HIV
    What is HIV?
   The acronym HIV stands for Human Immunodeficiency Virus.
   HIV is the virus that can lead to acquired immune deficiency syndrome,
    or AIDS.
   HIV is classified as a retrovirus. A retrovirus is a virus that encode the
    DNA and destroys the DNA and replace it with RNA or a virus
    containing RNA.
   There are three families of retroviruses: onco viruses (causing cancer),
    lenti viruses (slow viruses, of which HIV is one), and foamy viruses
    or spumaviruses.
   HIV damages a person’s body by destroying specific blood cells, called
    CD4+ T cells, which are crucial to helping the body fight diseases.
   There are two main forms of HIV: HIV-1 and HIV-2.
History Of HIV
 The earliest known case of infection with HIV-1 in a human was detected
  in a blood sample collected in 1959 from a man in Kinshasa, Democratic
  Republic of the Congo.( It is unknown of how he became infected with the
 In July of 1981, the New York Times reported an outbreak of a rare form
  of cancer among gay men in New York and California. This "gay cancer" as
  it was called at the time was later identified as Kaposi's Sarcoma, a disease
  that later became the face of HIV/AIDS. About the same time, emergency
  rooms in New York City began to see a rash of seemingly healthy young
  men presenting with fevers, flu-like symptoms, and a rare pneumonia called
  Kaposi Sarcoma.
 HIV-1 was discovered by Luc Montagnier and his associates at the Institute
  Pasteur in Paris in 1983. HIV-2 was first identified among patients in
  Cameroon in 1985. HIV-2 is more similar to SIV (Simian Immunodeficiency
  Virus) than is HIV-1 and it is less virulent than HIV-1 .
 Until a year later a US scientist, Dr. Robert Gallo confirmed that HIV was
  the cause of AIDS.
   In 1986, a second type of HIV, called HIV-2, was isolated from AIDS
    patients in West Africa. HIV-2 has the same modes of transmission
    as HIV-1 and is associated with similar opportunistic infections and
    AIDS. In persons infected with HIV-2, immunodeficiency seems to
    develop more slowly and to be milder, and those with HIV-2 are
    comparatively less infectious early in the course of infection. HIV-2
    infections are predominantly found in Africa. West African nations
    with a prevalence of HIV-2 of more than 1% in the general
    population are Cape Verde, Côte d'Ivoire (Ivory Coast), Gambia,
    Guinea-Bissau, Mali, Mauritania, Nigeria, and Sierra Leone. Other
    West African countries reporting HIV-2 are Benin, Burkina Faso,
    Ghana, Guinea, Liberia, Niger, São Tomé, Senegal, and Togo. Angola
    and Mozambique are other African nations where the prevalence of
    HIV-2 is more than 1%.
WHERE Did HIV Come From?
   Scientists identified that HIV 1 came from
    chimpanzees. While, HIV2 came from primates
    called the Sooty mangabey .
    They believe that the chimpanzee version of the
    immunodeficiency virus (called simian
    immunodeficiency virus or SIV) most likely was
    transmitted to humans and mutated into HIV when
    humans hunted these chimpanzees for meat and
    came into contact with their infected blood.
    Over decades, the virus slowly spread across Africa
    and later into other parts of the world.
  Transmission of HIV
 HIV is spread primarily by:
         Not using a condom when having sex with a person who has
HIV. All unprotected sex with someone who has HIV contains some risk.
However: Unprotected anal sex is riskier than unprotected vaginal sex.
Among men who have sex with other men, unprotected receptive anal
sex is riskier than unprotected anal sex.
   Having multiple sex partners or the presence of other sexually
      transmitted diseases (STDs) can increase the risk of infection
      during sex. Unprotected oral sex can also be a risk for HIV
      transmission, but it is a much lower risk than anal or vaginal sex.
      Sharing needles, syringes, rinse water, or other equipment used to
      prepare illicit drugs for injection.

   Being born to an infected mother—HIV can be passed from mother
     to child during pregnancy, birth, or breast-feeding.
    Transmission OF HIV
   Less Common Modes of Transmission
  Receiving blood transfusions, blood products, or organ/tissue transplants
   that are contaminated with HIV. This risk is extremely remote due to the
   rigorous testing of the U.S. blood supply and donated organs/tissue.
 HIV may also be transmitted through unsafe or unsanitary injections or
   other medical or dental practices. However, the risk is also remote with
   current safety standards in the U.S.
 Contact between broken skin, wounds, or mucous membranes and HIV-
   infected blood or blood-contaminated body fluids.These reports have also
   been extremely rare.
Contact between broken skin, wounds, or mucous membranes and HIV-
   infected blood or blood-contaminated body fluids.These reports have also
   been extremely rare.
Tattooing or body piercing present a potential risk of HIV transmission, but
   no cases of HIV transmission from these activities have been documented.
   Only sterile equipment should be used for tattooing or body piercing.
There is an extremely remote chance that HIV could be transmitted during
   “French” or deep, open-mouth kissing with an HIV-infected person if the
   HIV-infected person’s mouth or gums are bleeding.
Detection of HIV
   It can take some time for the immune system to produce enough
    antibodies for the antibody test to detect, and this time period can
    vary from person to person. This time period is commonly referred
    to as the “window period.” Most people will develop detectable
    antibodies within 2 to 8 weeks (the average is 25 days).
   Therefore, if the initial negative HIV test was conducted within the first 3
    months after possible exposure, repeat testing should be considered 3
    months after the exposure occurred.
    Ninety-seven percent (97%) of persons will develop detectable
    antibodies in the first 3 months. In rare cases, it can take up to 6
    months to develop antibodies to HIV.
Types of Test Used to Detect HIV
   Regular BLOOD TEST
    Enzyme-linked immunosorbent assay (ELISA)
   Western blot
   Polymerase chain reaction (PCR

          In 1985, a blood test became available that measures antibodies to HIV
that are the body's immune response to the HIV.
 The test used most commonly for diagnosing infection with HIV is referred to
   as an ELISA. If the ELISA finds HIV antibodies, the results must be confirmed,
   typically by a test called a Western blot.
 The western blot also known as the protein immunoblot is a widely used
   analytical technique used to detect specific proteins in the given sample of
   tissue homogenate or extract. It uses gel electrophoresis to separate native
   proteins by 3-D structure or denatured proteins by the length of the
 Polymerase chain reaction (PCR
 This test finds either the RNA of the HIV virus or the HIV DNA in white
   blood cells infected with the virus. PCR testing is not done as frequently as
   antibody testing, because it requires technical skill and expensive equipment.
Stages OF HIV
   STAGE 1 : Primary HIV infection
 This stage of infection lasts for a few weeks and is often accompanied by a
  short flu-like illness. In up to about 20% of people the HIV symptoms are
  serious enough to consult a doctor, but the diagnosis of HIV infection is
  frequently missed.
 During this stage there is a large amount of HIV in the peripheral blood and
  the immune system begins to respond to the virus by producing HIV
  antibodies and cytotoxic lymphocytes. This process is known as
  seroconversion. If an HIV antibody test is done before seroconversion is
  complete then it may not be positive.
   STAGE 2 : Clinically asymptomatic stage
 This stage lasts for an average of ten years and, as its name suggests, is free
  from major symptoms, although there may be swollen glands. The level of
  HIV in the peripheral blood drops to very low levels but people remain
  infectious and HIV antibodies are detectable in the blood, so antibody tests
  will show a positive result.
 Research has shown that HIV is not dormant during this stage, but is very
  active in the lymph nodes. A test is available to measure the small amount of
  HIV that escapes the lymph nodes. This test which measures HIV RNA (HIV
  genetic material) is referred to as the viral load test, and it has an important
  role in the treatment of the HIV infection.
    HIV Stages
   STAGE 3 : Symptomatic HIV infection
   Over time the immune system becomes severely damaged by HIV. This is thought to happen for three main
   The lymph nodes and tissues become damaged or 'burnt out' because of the years of activity;
   HIV mutates and becomes more pathogenic, in other words stronger and more varied, leading to more T
    helper cell destruction;
   The body fails to keep up with replacing the T helper cells that are lost.
   Antiretroviral treatment is usually started once an individuals CD4 count (the number of T helper cells)
    drops to a low level, an indication that the immune system is deteriorating. Treatment can stop HIV from
    damaging the immune system, therefore, HIV-infected individuals on treatment usually remain clinically
    asymptomatic. Symptomatic HIV infection is mainly caused by the emergence of certain opportunistic
    infections that the immune system would normally prevent.
   STAGE 4 : Progression from HIV to AIDS

   As the immune system becomes more and more damaged the individual may develop
    increasingly severe opportunistic infections and cancers, leading eventually to an AIDS
   A clinical criteria is used by WHO to diagnose the progression to AIDS, this differs slightly
    between adults and children under five. In adults and children (aged 5 or over) the progression
    to AIDS is diagnosed when any condition listed in clinical stage 4 is diagnosed and/or the CD4
    count is less than 200 cells/mm3 or a CD4 percentage less than 15. In children younger than
    five, an AIDS diagnosis is based on having any stage 4 condition and/or a CD4 percentage less
    than 20 (children aged 12-35 months) and a CD4 percentage less than 25 (children less than
    12 months). The criteria for diagnosing AIDS may differ depending on individual country
                     System                              Examples of Infection/Cancer

                                                         •Pneumocystis jirovecii Pneumonia
                     Respiratory system                  (PCP)
                                                         •Tuberculosis (TB)
                                                         •Kaposi's Sarcoma (KS)
                     Gastro-intestinal system            •Cytomegalovirus (CMV)
                                                         •Kaposi's Sarcoma
                     Central/peripheral Nervous system
                                                         •Non Hodgkin's lymphoma
                                                         •Varicella Zoster
                                                         •Herpes simplex
                                                         •Herpes simplex
                     Skin                                •Kaposi's sarcoma
                                                         • Varicella Zoster

This table shows examples of common opportunistic infections
and cancers that affect the body systems.

   Fever
   Muscle soreness
   Rash
   Headache
   Sore throat
   Mouth or genital ulcers
   Swollen lymph glands, mainly on the neck
   Joint pain
   Night sweats
   Diarrhea
        Treatment of HIV
   This is the main type of treatment for HIV or AIDS. It is not a cure,
    but it can stop people from becoming ill for many years. The
    treatment consists of drugs that have to be taken every day for the
    rest of a person’s life.
   The aim of antiretroviral treatment is to keep the amount of HIV in
    the body at a low level. This stops any weakening of the immune
    system and allows it to recover from any damage that HIV might
    have caused already.
   Why do people need to take more
    than one drug at a time? If only one drug was
    taken, HIV would quickly become resistant to it and the drug would
    stop working. Taking two or more anti retroviral at the same time
    vastly reduces the rate at which resistance would develop, making
    treatment more effective in the long term.
   Each of the classes of anti-HIV drugs blocks the virus in different ways. It's best to combine at least
    three drugs from two different classes to avoid creating strains of HIV that are immune to single drugs.
    The classes of anti-HIV drugs include:

   Non-nucleoside reverse transcriptase inhibitors (NNRTIs). NNRTIs disable a protein needed
    by HIV to make copies of itself. Examples include efavirenz (Sustiva), etravirine (Intelence) and
    nevirapine (Viramune).

   Nucleoside reverse transcriptase inhibitors (NRTIs). NRTIs are faulty versions of building blocks
    that HIV needs to make copies of itself. Examples include Abacavir (Ziagen), and the combination drugs
    emtricitabine and tenofovir (Truvada), and lamivudine and zidovudine (Combivir).

   Protease inhibitors (PIs). PIs disable protease, another protein that HIV needs to make copies of
    itself. Examples include atazanavir (Reyataz), darunavir (Prezista), fosamprenavir (Lexiva) and ritonavir

   Entry or fusion inhibitors. These drugs block HIV's entry into CD4 cells. Examples include
    enfuvirtide (Fuzeon) and maraviroc (Selzentry).

   Integrase inhibitors. Raltegravir (Isentress) works by disabling integrase, a protein that HIV uses to
    insert its genetic material into CD4 cells.
                                      This is a two-dimensional representation of
   The normal phosphorylated         AZT with a phosphate group attached to
    thymidine molecule can be         the 5' -OH group (i.e., the -OH group
    phosphorylated (addition of a     attached to the 5' carbon of the sugar). AZT
    phosphate group) to become        stands for "azidothymidine" because it
    one of the nucleotide building    resembles thymidine but has an azido (-N3)
    blocks of a DNA strand. The       group in the 3' position (i.e., attached to the
    3' -OH group (i.e., the -OH       3' carbon) of the sugar portion of the
    group attached to the 3'          molecule. This azido group terminates the
    carbon of the sugar) allows       nucleic acid chain because it cannot bond to
    thymidine to bond to another      another nucleotide.
    nucleotide via the phosphate
    linkage, continuing the nucleic
    acid chain.
Prevention of Hiv
   Know your HIV status. Everyone between the ages of 13 and 64 should be
    tested for HIV at least once. If you are at increased risk for HIV, you should
    be tested for HIV at least once a year.
   Abstain from sexual activity or be in a long-term mutually monogamous
    relationship with an uninfected partner.
   Limit your number of sex partners. The fewer partners you have, the less
    likely you are to encounter someone who is infected with HIV or another
   Correct and consistent condom use. Latex condoms are highly effective at
    preventing transmission of HIV and some other sexually transmitted
    diseases. “Natural” or lambskin condoms do not provide sufficient
    protection against HIV infection.
   Male circumcision has also been shown to reduce the risk of HIV
    transmission from women to men during vaginal sex.
   Do not inject drugs. If you inject drugs, you should get counseling and
    treatment to stop or reduce your drug use.
Prevention of HIV
   Obtain medical treatment immediately if you think you were
    exposed to HIV. Sometimes, HIV medications can prevent infection
    if they are started quickly. This is called post-exposure prophylaxis.
    The post-exposure prophylaxis is preventative medications given
    after an HIV or suspected HIV exposure in hopes of decreasing the
    likelihood of HIV infection from the exposure. The PEP medication
    combinations used depends on the degree of exposure and the
    HIV status of the source of the exposure. For instance, accident in
    a HIV research laboratory.
   Participate in risk reduction programs. Programs exist to help
    people make healthy decisions, such as negotiating condom use or
    discussing HIV status.
     Since the AIDS epidemic began in 1981, 1.7 million Americans have been infected with
    HIV and 583,298 have died of AIDS-related causes through 2007.
    1.1 million Americans are living with HIV (including more than 468,000 with AIDS).
    An estimated 21% of people living with HIV are undiagnosed.
    Every 9 1/2 minutes, someone in the U.S. is infected with HIV.
    Gay and bisexual men continue to bear the greatest burden of HIV infection, accounting
    for an estimated 53% of new HIV infections.
    African-Americans and Latinos are disproportionately affected by HIV and AIDS. Blacks
    accounted for 45% of new HIV infections in 2006 and 47% of those living with the disease,
    yet they make up only 12% of the U.S. population. Latinos account for 17% of new
    infections yet comprise 15% of the U.S. population, while whites represent 35% of new
    infections and account for 66% of the total population.
    The AIDS case rate for African Americans is more than 9 times that of whites, and the
    HIV rate is 7 times greater among blacks than whites. Survival after an AIDS diagnosis is
    lower for blacks than any other racial/ethnic group.
           71% of all AIDS cases reported since the beginning of the epidemic are
    concentrated in 10 states or territories. While the District of Columbia has the highest
    AIDS case rate (148.1 per 100,000 in 2007), the states of New York (17.6%), California
    (14.4%) and Florida (10.6%) have the most cumulative AIDS cases.
    Random HIV Questions
   Why is it difficult to develop a HIV vaccination?
   Unlike other viruses HIV destroys the immune system cells that are meant to fight
    against it.
   Soon after infection, HIV inserts its genetic material into human cells, where it remains
    hidden from the immune system
   HIV occurs in several subtypes, each of which is very different from the others.
   Nobody has ever recovered from HIV infection, so there is no natural mechanism to
    What does HIV look like?
Outside of a human cell, HIV exists as roughly spherical particles (sometimes called virions).
  The surface of each particle is studded with lots of little spikes.

Why HIV must infect a host cell in order to reproduce?
    The virus has to find a host cell in order to take over. After taking over the host cell the
    virus slowly implants its genetic makeup into the cell. At that point the virus can either lie
    dormant--such as in some cases of the HIV/AIDS virus--or immediately start reproducing.
    Instead of the virus splitting and reproducing in that manner, the virus implants its genetic
    makeup into the hosts cell. As the host cell reproduces, its replicates have the genetic
    makeup of the virus instead of the original cell.
    Chemistry of HIV
   HIV Infection Cycle
 The first step in HIV's attack on helper T cells is attaching to the cell. Helper T
  cells contain proteins called CD4 proteins in their cell membrane that extend
  outside of the cell. Normally, these proteins help the cells to bind to antigens
  (infectious particles) in order to stimulate activation of the helper T cells, and
  they are also required for normal T cell development. Unfortunately,
  however, CD4 proteins also function as receptors for HIV, allowing
  the virus to attach itself to the cell and thereby gain access to the
  cell's biochemical machinery.
 Once the virus has attached to a helper T cell, it injects its genetic
  information (as RNA) into the cell, along with the enzyme reverse
 Reverse transcriptase catalyzes the production of DNA from the
  viral RNA, making a DNA copy of the virus's genetic material. This
  DNA copy is capable of incorporating itself into the cell's genetic material,
  because it is now in the same form as the cell's chromosomes. Hence, the
  step catalyzed by reverse transcriptase is one of the most important
  steps in the infection cycle.
Chemistry of HIV
   The viral DNA copy then enters the nucleus of the infected
    helper T cell, where it is incorporated into the cell's genetic
    material (i.e., the chromosomes).
   Using the cell's own DNA-replication mechanisms, the viral DNA
   Using the cell's mechanisms for producing proteins from the genetic
    information contained in DNA, many copies of the proteins needed
    by the virus are made from the replicated HIV DNA. As part of
    this step, RNA copies of the viral DNA are made.
   When they are first synthesized, the proteins are too long (containing
    extra fragments) to be assembled into new viruses. They must be cut to
    their proper size. The HIV enzyme protease, which is produced by the
    cell's biochemical machinery from the viral DNA incorporated into the
    cell's chromosomes, catalyzes the cutting of these proteins to their proper
   New HIV particles (viruses) are assembled inside the cell from the
    cut viral proteins and the viral RNA copies.
   Once assembled, the new viruses then burst out of the host cell
    (killing it) and invade new cells, continuing the infection.
Chemistry of HIV
This diagram summarizes the
classification and functions of
the major types of cells in the
immune system. Note that
the helper T cells, a specific
type of leukocyte, are the
target for HIV infection
 Overview
 In order for HIV to reproduce, HIV
  infects an immune cell called the helper T
  cell. (T cells help control the body's
  response to many types of infections.)
 HIV can affect anyone but it is up to you
  to make the right choices in checking
  your status. No one can lead our lives for
  us. We are responsible for our actions.

To top