Objectives:
1) To discuss the function of the immune system, in terms of non-specific and specific lines of defense for protection of diseases;
2) To discuss the experimental tools that can be used to detect disease causing agents;
3) To participate in a laboratory simulation of the transmission and spread of HIV, using a sample of simulated body fluid;
4) To discuss the modes of transmission for HIV , social implications and recent developments in treatment.

LECTURE ON THE IMMUNE SYSTEM AND H.I.V.

I.   The Immune System

1.Immunity - to protect the body against foreign antigen through the recognition of the bodies own cells and molecules (self) from foreign cells and molecules (non-self)
2.   Pathogens - antigens that the body recognizes as foreign
3.   Protection
A.Non-specific mechanisms - mechanisms to prevent infection that are not aimed at a certain pathogen, but rather can prohibit infection by a number of pathogens, skin, mucous membranes, saliva and tears, fever, transferrin, interferon, complement system, phagocytes, natural killer T-cells
B.Specific lines of defense - chemical and cellular mechanisms of recognizing, attacking, and remembering antigens, produced by the body. This is sub-divided into two areas:
1) Cellular immunity is provided from T-cells. Cells must recognize fragments of processed antigens and MHC antigens (found on the surface of all nucleated cells and encoded by chromosome six).
                           a) cytotoxic t-cells - lyse cells
 b) helper t-cells - binds antigens before b-cells are activated; helps to amplify antibody production
              c) memory t-cells - provides immunological memory for future exposure
              d) suppresser t-cells - suppresses the immune response well underway
2) Antibody mediated (Humoral) immunity from B-cells. B-cells bind with antigens; become activated and divide to produce two cells types:
a) plasma cells that will produce antibodies at the rate of 2000 molecules per second
b) memory cells that will remain in the blood and lymphatic tissues, waiting for a subsequent infection from the same antigen

1).   http://www.cdcnac.org/stdpics.html

1) Causative agent is the retrovirus that suppresses specific components, i.e. helper T-cells and macrophages, of the immune system.
2) Transmission is through bodily fluids, such as trans-placenta, breast milk, blood, semen, and vaginal fluids, but not through kissing and not through contaminated insects.
3) Disease was first reported in 1981. Early spread of this disease was through heterosexual relations in Africa, then homosexual relations in USA and Europe. More recent transmission is through sharing needles for intravenous drug use, contaminated blood from blood banks for hemophiliacs, and more recently through heterosexual intercourse.
4). Past exposure through:
      a.   73% homosexual/bisexual men
      b.   17% present/past intravenous drug users
      c.   3% blood product recipient prior to 1985
      d.   1% infants born to infected mothers
      e.   6% not placed in these categories
5)Virus enters the body and invades a somatic cell. Reverse transcriptase copies RNA to DNA, which is inserted into the host cell. The host cell is usually helper T cells. This leads to a decrease in helper T-cells, which function to help activate B-cells.

IV.  HIV Laboratory
     1.   ELISA
            A.Elisa (Enzyme Linked Immuno Sorbent Assay), used to see if fluid contains antibodies to antigen of interest.
               1.   http://www.lrc.arizona.edu/mmiweb/lake.html
                    a.   HIV testing with ELISA
                         1.inactivated purified antigens in wells
                         2.HIV positive serum will contain antibodies to antigens
                         3.another antibody against humans coupled with a colorizer
                    b. false positive - recognize only the human leukocyte antigen (HLA) usually coupled with the HIV antigen
                    c. false negative - have a six-twelve month window for seroconversion,
                                              - time to recognize and produce antibodies to the HIV antigen
                    d. positive patients will be tested with western blot

B. In this test, contaminated or uncontaminated specimen will be placed into the well. Contaminated specimen will contain Biotin and Bovine Serum Albumin, which will act as HIV virus. Streptavidin will have a high affinity for Biotin and BSA, acting as a second antibody. Peroxidase will become oxidized and change in color to blue for a positive test.

          D.   Controls
               1. positive (+) control - will contain the simulated antigen (BSA)
               2. negative (-) control - will not contain the BSA
 

Debates on Topics Associated with HIV/AIDS

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