Immunology of HIV Infection Post-Test PDF

## IMMUNOLOGY OF HIV INFECTION ### Posttest Select the best answer for each question. Please mark your answers on this exam. Be sure you have identified yourself on the form. Only one answer is correct. 1. The adaptive immune response to HIV - is mediated by antibodies only - is weak wit...

## IMMUNOLOGY OF HIV INFECTION ### Posttest Select the best answer for each question. Please mark your answers on this exam. Be sure you have identified yourself on the form. Only one answer is correct. 1. The adaptive immune response to HIV - is mediated by antibodies only - is weak with a poor antibody response - is capable of preventing viral replication and spread during the first two days after infection. - **delays progression to AIDS** - does not result in production of complement activating antibodies 2. Because the virus responsible for HIV infection integrates into the genome of T cells - HIV can only be transmitted to others via fluids containing viable T cells - the diagnosis of HIV relies entirely on demonstrating the presence of viral RNA in lymphocytes - it is always transmitted from mother to fetus in the absence of treatment - transmission from mother to fetus cannot occur during a normal pregnancy - **it can stay hidden from the immune system as a provirus in resting T cells** 3. A Delayed Type Hypersensitivity (DTH) test - is a technique used to measure the immune response to HIV - can be used to demonstrate T cell mediated immunity in vitro (takes 48 hrs.) - is irrelevant as an indicator of a patient's T cell memory function because the HIV is continuously mutating. - is particularly useful in testing for HIV infection in the newborn because a baby only has maternal antibodies - **will be positive (red, raised spot at test site) if the individual tested has memory T cells that recognize the antigen used in the test** 4. The measurement of CD4-positive T cells in HIV infected patients is useful for - **making decisions on anti-viral treatment (initiation/type of treatment etc.)** - predicting the patient's predisposition to develop opportunistic infections such as Pneumocystis jiroveci - classifying HIV-infected persons by CDC (Center for Disease Control) HIV classification system - **for monitoring treatment outcome in clinical trials of AIDS treatment** 5. Antibodies to the following cluster determinant (CD) molecules are used to characterize T-helper cells. - CD3 and CD8 - CD4 and CD8 - CD3 and CD4 - CD19 and CD4 - **all of the above** 6. The ELISA test used to screen for antibodies to the HIV will - always be positive if serum from an infected individual is tested - always be negative if serum from an individual never exposed to HIV is tested - be considered positive when the O.D. (optical density) for the serum tested is lower than the cutoff O.D. - be considered positive when the O.D. value for the serum tested is higher than the cutoff O.D. - **only be positive if the antibodies to the viral antigens are of IgG class.** 7. The CD4 molecule is NOT: - a cell surface molecule expressed on helper T lymphocytes - an accessory molecule on T lymphocytes that interacts with HLA-class II molecules - **the primary cellular receptor for HIV** - a 55 kD protein belonging to the immunoglobulin supergene family - present on resting B cells 8. The ratio of CD4 to CD8 cells early in HIV infection - increases due to an absolute increase in CD4 positive T cells - **decreases due to an absolute increase in CD8 T cells and fall in CD4 T cells** - decreases due to a loss of CD4 molecules on the helper T cells - decreases due to a drop in absolute numbers of B cells and monocytes - increases due to a drop in absolute numbers of CD8 cells 9. Overt AIDS - always occurs a minimum of 12 years after being infected with HIV - occurs in about 50% of those infected with HIV - **is the result of increased HIV replication leading to destruction of CD4 positive T cells and therefore to immunodeficiency** - is genetically determined and occurs in those who are blood group A positive, but not in those who are blood group B - will not occur in HIV infected individuals if they practice safe sex 10. Opportunistic infections occur when HIV virus load increases because - HIV activates common pathogens to replicate - HIV infected individuals are usually exposed to a greater number of infectious agents - **by then T cell immunity has degenerated** - the number of circulating phagocytic cells has decreased at this stage - by now the individual is only able to make T cells with T cell receptors specific for HIV epitopes