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Questions and Answers
PCR can reveal an HIV infection before ______ can be detected.
PCR can reveal an HIV infection before ______ can be detected.
antibodies
AIDS is caused by the retrovirus human immunodeficiency virus (HIV) and is characterized by profound ______.
AIDS is caused by the retrovirus human immunodeficiency virus (HIV) and is characterized by profound ______.
immunosuppression
HAART combines two types of ______ drugs.
HAART combines two types of ______ drugs.
antiretroviral
NRTI's provide faulty DNA building blocks, stopping the ______ chain the virus uses to make copies of itself.
NRTI's provide faulty DNA building blocks, stopping the ______ chain the virus uses to make copies of itself.
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HIV is primarily transmitted via unprotected sexual intercourse, contaminated blood transfusions, hypodermic ______, and during pregnancy.
HIV is primarily transmitted via unprotected sexual intercourse, contaminated blood transfusions, hypodermic ______, and during pregnancy.
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As of the end of 2001, approximately ______ million people were estimated to be living with HIV/AIDS.
As of the end of 2001, approximately ______ million people were estimated to be living with HIV/AIDS.
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The risk of opportunistic infections is high when CD4 T cells is below ______ cells/µl.
The risk of opportunistic infections is high when CD4 T cells is below ______ cells/µl.
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Fusion Inhibitors block HIV before it enters the human ______ cell.
Fusion Inhibitors block HIV before it enters the human ______ cell.
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The two main variants of HIV are HIV-1 and ______.
The two main variants of HIV are HIV-1 and ______.
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A normal CD4 lymphocyte count ranges from ______ to 1,200.
A normal CD4 lymphocyte count ranges from ______ to 1,200.
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Integrase Inhibitors aim to block the integration of the virus's ______ into the cell's chromosome.
Integrase Inhibitors aim to block the integration of the virus's ______ into the cell's chromosome.
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Symptoms such as persistent white spots or unusual lesions on the ______ can indicate advanced HIV infection.
Symptoms such as persistent white spots or unusual lesions on the ______ can indicate advanced HIV infection.
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The HIV virus transforms its ss-RNA genome into ds-DNA for integration into its ______ genome.
The HIV virus transforms its ss-RNA genome into ds-DNA for integration into its ______ genome.
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The enzyme-linked immunosorbent assay (ELISA) is usually the first test used to detect infection with ______.
The enzyme-linked immunosorbent assay (ELISA) is usually the first test used to detect infection with ______.
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The protein coat of the HIV virus contains marker proteins known as ______.
The protein coat of the HIV virus contains marker proteins known as ______.
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A CD4 count of 200 or less increases the likelihood of developing certain types of ______.
A CD4 count of 200 or less increases the likelihood of developing certain types of ______.
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While CD4 is recognized by the virus, it also needs a ______ signal for viral attack.
While CD4 is recognized by the virus, it also needs a ______ signal for viral attack.
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The HIV strain that is involved in competitive inhibition for binding is called ______.
The HIV strain that is involved in competitive inhibition for binding is called ______.
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The coreceptor for T cells involved in HIV infection is ______, which acts as a receptor for SDF-1.
The coreceptor for T cells involved in HIV infection is ______, which acts as a receptor for SDF-1.
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Common symptoms of HIV in children can include difficulty gaining ______.
Common symptoms of HIV in children can include difficulty gaining ______.
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The HIV gp120 surface protein binds to ______ on the target cell.
The HIV gp120 surface protein binds to ______ on the target cell.
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The ______ test is used to confirm the results of two positive ELISA tests.
The ______ test is used to confirm the results of two positive ELISA tests.
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The transmembrane component, gp41, binds the coreceptor ______ to enhance fusion.
The transmembrane component, gp41, binds the coreceptor ______ to enhance fusion.
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The Polymerase Chain Reaction (PCR) test detects the ______ of HIV.
The Polymerase Chain Reaction (PCR) test detects the ______ of HIV.
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The viral genome is transcribed by the reverse transcriptase (RT) into a ______ genome.
The viral genome is transcribed by the reverse transcriptase (RT) into a ______ genome.
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The double-stranded DNA molecule that is formed from the viral genome is called a ______.
The double-stranded DNA molecule that is formed from the viral genome is called a ______.
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During infection, the virus primarily infects ______ cells within local mucosal surfaces.
During infection, the virus primarily infects ______ cells within local mucosal surfaces.
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A marked drop in the number of circulating ______+ T cells is associated with rapid viral replication.
A marked drop in the number of circulating ______+ T cells is associated with rapid viral replication.
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When CD4+ T cells decline below ______ cells/µl, infections with opportunistic microbes can occur.
When CD4+ T cells decline below ______ cells/µl, infections with opportunistic microbes can occur.
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Study Notes
Acquired Immunodeficiency Syndrome (AIDS)
- AIDS is a disease caused by the retrovirus HIV, leading to profound immunosuppression.
- This can result in opportunistic infections, secondary cancers, and neurological problems.
Secondary Immunodeficiencies
- HIV transmission mainly happens through unprotected sex, contaminated blood products, needles, and during pregnancy/breastfeeding.
- Saliva and tears do not transmit HIV.
Epidemiology and Statistics
- Since its discovery in 1981, AIDS has become an epidemic.
- Globally, an estimated 42 million people are living with HIV/AIDS.
- 38.6 million are adults, 19.2 million are women, and 3.2 million are children under 15.
- Genetic research suggests HIV originated in West-Central Africa in the late 19th or early 20th century.
- HIV/AIDS has had a significant impact on society, causing illness and discrimination.
Global Estimates of HIV/AIDS (2001)
- Global map showing estimated numbers of adults and children with HIV/AIDS, as of end 2001.
- Various regions have variable numbers reported (in millions).
- Total estimated adults and children living with HIV/AIDS: 40 million.
HIV and Life Cycle
- Two main types of HIV: HIV-1 and HIV-2.
- HIV is a retrovirus with two copies of single-stranded RNA genome.
- The genome contains gag (core protein), pol (enzymes), and env (envelope protein).
- The virus encodes 6 regulatory and accessory proteins.
HIV and Host Cell Infection Mechanisms
- HIV uses reverse transcriptase to convert viral RNA to DNA, which then integrates into the host's DNA.
- HIV has marker proteins (gp120) on its surface to recognize and infect specific immune cells.
- The protein coat contains MHC-I and MHC-II molecules.
Complete Activation of HIV
- CD4 is recognized by the virus but a costimulatory signal is necessary for viral attack.
- T cells: coreceptor is CXCR4, which also acts as a receptor for the chemokine SDF-1.
- There is competitive inhibition between chemokine and HIV, leading to the T-tropic HIV strain.
Infection of Human Cell with HIV
- HIV gp120 surface protein binds CD4 on target cells.
- Transmembrane component gp41 binds coreceptor CXCR4 for fusion.
- Viral genome and proteins enter the host cell within a nucleocapsid.
- Reverse transcriptase transcribes the viral ssRNA genome into a double-stranded DNA molecule (provirus).
- The provirus is integrated into the host's DNA.
HIV Replication and Host Impact
- Virus infects helper T cells (TH) in local mucosal surfaces.
- Rapid spread to lymphoid tissue, glial cells, and genital secretions.
- Cytotoxic T cells appear within weeks of initial infection.
- Neutralizing antibodies may appear.
- Replication process begins after a short period.
HIV Replication and the Immune System
- Hosts develop an immune response, but high viral replication error rates mean high mutation rates.
- Repeated replication and mutation allow HIV to persist in lymph nodes.
- Infected cells can be killed directly or indirectly by immune mechanisms.
- After months, a balance is established between virus replication, immune response, and available cells, with the disease entering a chronic phase.
- High rate of viral replication leads to a decline in circulating CD4+ T cells.
HIV Impact on Lymphoid Organs and Immune Cells
- 99% virus replication in CD4+ T cells of lymphoid organs, 1% in monocytes and resting CD4+ T cells.
- HIV infection with CD4+ T cells declining below 200 cells/µL leads to opportunistic infections.
- Risk of opportunistic infections and malignancies increases when CD4+T cell count is below 50 cells/µL.
- Rate of immunologic and clinical progression varies between individuals, closely tied to virus replication.
AIDS Signs and Symptoms
- Early symptoms resemble a flu, lasting 2-4 weeks. -Common symptoms: fever, headache, sore throat, swollen lymph nodes, rash, diarrhea, weight loss. -Opportunistic infections like Pneumocystis carinii pneumonia (PCP) appear as the immune system weakens.
- CD4 lymphocyte count below 200 cells per microliter (µL) suggests immune deficiency.
- Soaking night sweats, dry cough, shortness of breath, and persistent/high fever are later-stage symptoms.
- Persistent white spots/lesions, headaches, blurred vision, and prolonged lymph node swelling also occur.
- Associated cancers, like Kaposi's sarcoma, may develop.
- Children experience different symptoms like difficulty gaining weight, delayed development, and increased susceptibility to childhood illnesses.
HIV Testing
- ELISA is the initial screening test for HIV antibodies.
- Western blot confirms a positive ELISA result to rule out false positives.
- Indirect fluorescent antibody (IFA) and polymerase chain reaction (PCR) tests may confirm results or detect HIV earlier.
HIV Treatment
- Highly Active Antiretroviral Therapy (HAART) is the main treatment, using a combination of antiretroviral drugs like nucleoside reverse transcriptase inhibitors (NRTIs).
- HAART considers 200 to 350 CD4+ cells/mm3 as a target range.
- Other classes include non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors.
Future of HIV Treatment
- Scientists are researching more potent protease inhibitors, less toxic reverse transcriptase inhibitors, and new drug classes, such as fusion and integrase inhibitors.
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Description
This quiz covers key aspects of Acquired Immunodeficiency Syndrome (AIDS) caused by the HIV virus. It includes information on transmission, epidemiology, and global statistics since the disease's discovery. Test your knowledge on the impact of AIDS on society and current estimates around the world.
