HIV Structure and Characteristics

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Questions and Answers

When was the HIV virus first successfully identified and classified?

1982

1981 (correct)

1983

1980

According to 2003 estimates, how many people were infected with HIV/AIDS in the United States?

1,200,000 - 1,400,000

1,039,000 - 1,185,000 (correct)

900,000 - 1,000,000

1,500,000 - 1,600,000

What is the primary route of transmission of HIV during pregnancy?

Through the placenta

During delivery

Through breast milk

All of the above (correct)

What is the primary cell type that HIV attaches to and fuses with?

CD4 lymphocytes Signup and view all the answers

What is the result of the reverse transcriptase process in the HIV life cycle?

Formation of viral DNA Signup and view all the answers

What is the primary effect of HIV infection on the immune system?

Leukopenia Signup and view all the answers

What is the result of the destruction of CD4 lymphocytes by HIV?

Increased susceptibility to opportunistic infections and malignancies Signup and view all the answers

In which region did HIV infection rates increase by more than 50% between 2004 and 2006?

Eastern Europe and Central Asia Signup and view all the answers

What is the most critical reagent of an HIV test?

Purest quality HIV antigen Signup and view all the answers

What is the function of the gp120 protein?

To bind to CD4 cells Signup and view all the answers

What is the purpose of indirect immunofluorescence in HIV testing?

To detect HIV antibody and virus Signup and view all the answers

What is the limitation of the p24-antigen screening assay?

Unpredictable appearance and rate of rise Signup and view all the answers

What is the principle of the Polymerase Chain Reaction (PCR) in HIV testing?

Amplifying HIV DNA Signup and view all the answers

What is the purpose of using radioactive or biotinylated probes in PCR?

To detect HIV DNA using probes Signup and view all the answers

What is the best sample for virus isolation in HIV diagnosis?

Peripheral blood Signup and view all the answers

How is infection confirmed in virus isolation?

Detecting reverse transcriptase or p24 antigen Signup and view all the answers

What is the shape of the HIV virus?

Icosahedral (20 sided) Signup and view all the answers

What is the function of the gp120 protein in the HIV virus?

To bind to target cells Signup and view all the answers

Which of the following is a characteristic of HIV infections?

Persistent infection Signup and view all the answers

What is the genus of the retroviridae family that HIV belongs to?

Lentivirus Signup and view all the answers

What is the term used to describe the syndrome caused by HIV infection?

Acquired Immune Deficiency Syndrome (AIDS) Signup and view all the answers

According to the history of HIV, what was the year of the first proven AIDS death?

1959 Signup and view all the answers

Which type of HIV is more virulent and relatively easy to transmit?

HIV-1 Signup and view all the answers

What is the name of the enzyme responsible for transcribing RNA to DNA in HIV?

Reverse Transcriptase Signup and view all the answers

What is the average incubation period of HIV before it leads to AIDS?

10 years Signup and view all the answers

What is the most advanced stage of AIDS classified as?

Having < 200 CD4+ T cells/cubic millimeter of blood Signup and view all the answers

What is the primary function of ELISA testing?

To detect antibodies against HIV in blood samples Signup and view all the answers

What is the purpose of the Western Blot test?

To confirm the presence of HIV antibodies in a sample Signup and view all the answers

What is the name of the cancer commonly associated with HIV infection?

Kaposi's sarcoma Signup and view all the answers

What is the name of the bacterial infection that can occur in people with HIV?

Mycobacterium avium complex Signup and view all the answers

What is the name of the fungal infection that can occur in the mouth of people with HIV?

Oral candidiasis Signup and view all the answers

What is the primary function of CD4+ T cells in the immune system?

To fight off viral infections Signup and view all the answers

Which of the following methods is NOT recommended for preventing HIV infection?

Sharing needles/syringes Signup and view all the answers

What is the purpose of a therapeutic vaccine?

To boost the immune system of those already infected Signup and view all the answers

What is the effect of male circumcision on HIV infection?

It reduces susceptibility to infection by sevenfold Signup and view all the answers

What is the mechanism of post-coital penile hygiene?

It kills the virus before it infects Signup and view all the answers

What is the purpose of nucleoside reverse transcriptase inhibitors?

To inhibit the reverse transcription process Signup and view all the answers

What is the current status of HIV vaccines?

No vaccines are approved by the FDA Signup and view all the answers

Study Notes

HIV Introduction

HIV is a viral infection that destroys helper T cells of the immune system
HIV is a lentivirus, belonging to the genus of the retroviridae family
Characterized by long incubation periods and persistent infection
Infects a wide range of primate hosts, as well as some non-primate mammals

Morphology

Icosahedral (20-sided) shape
Retroviruses transcribe RNA to DNA
Two viral strands of RNA found in the core, surrounded by a protein outer coat
Enveloped virus with a lipid matrix containing specific viral glycoproteins
gp120 (wedge-shaped) and gp41 (knob-like) structures responsible for binding to target cells

Types of HIV

Two species of HIV infect humans: HIV-1 and HIV-2
HIV-1 is more virulent, relatively easy to transmit, and accounts for the majority of HIV infections globally
HIV-2 is less transmittable and largely confined to West Africa

Origins of HIV

HIV-1 likely descended from SIVcpz (Simian Immunodeficiency Virus of chimpanzees)
HIV-2 likely descended from SIVsm (Simian Immunodeficiency Virus of sooty mangabeys)

History

1926-1946: Scientists believe HIV first spread from monkeys to humans
1959: First proven AIDS death
1978: Gay men in the US and Sweden begin showing signs of what is now known as AIDS
1981: CDC notices an increase in cases of Kaposi’s sarcoma and Pneumocystis carinii pneumonia
1982: The term AIDS (Acquired Immune Deficiency Syndrome) is used for the first time
1983: Institute Pasteur isolates HIV-1; CDC issues warning to blood banks about potential problem
1984: Dr. Robert Gallo claims discovery of HIV

Epidemiology

The virus was first successfully identified and classified in 1981
By the end of 2003, 1,039,000 to 1,185,000 persons were infected with HIV/AIDS in the US
Global statistics (2006): 39.5 million infected with HIV/AIDS, with 4.3 million new infections
2.8 million (65%) of these new infections were in sub-Saharan Africa
Increases in Eastern Europe and Central Asia, with a more than 50% rise in infection rates since 2004
2.9 million deaths due to AIDS-related illnesses in 2006

Transmission

Sharing of infected drug injection needles/syringes
Accidental needle stick (healthcare professionals)
Unprotected sex with infected individual
Blood transfusions/Organ transplants
Transmission from infected mother-to-fetus during pregnancy or delivery
Transmission from breast milk of infected mother to her baby

Pathogenesis and Virulence Factors

HIV enters through mucous membrane or skin and travels to dendritic phagocytes beneath the epithelium, multiplies, and is shed
Virus is taken up and amplified by macrophages in the skin, lymph organs, bone marrow, and blood
HIV attaches to CD4 and coreceptor; HIV fuses with cell membrane
Reverse transcriptase makes a DNA copy of RNA
Viral DNA is integrated into host chromosome
Can produce a lytic infection or remain latent

Primary and Secondary Effects of HIV Infection

Primary effects: extreme leukopenia, formation of giant T cells, and infected macrophages releasing the virus in the central nervous system
Secondary effects: destruction of CD4 lymphocytes, allowing for opportunistic infections and malignancies

Clinical Manifestations

Human Immunodeficiency Virus (HIV) has an incubation period of about 10 years and eventually leads to Acquired Immunodeficiency Syndrome (AIDS)
AIDS results in the impairment of the immune system, leading to death from infections, secondary diseases, or many different types of cancers
Common diseases associated with HIV infection: Kaposi's sarcoma (KS), Pneumocystis carinii pneumonia (PCP), and Mycobacterium avium complex (MAC)

Laboratory Tests

Methods utilized to detect: Antibody, Antigen, Viral nucleic acid, and Virus in culture
ELISA testing: detects antibodies directed against p24, gp120, gp160, and gp41
Western Blot: utilizes a lysate prepared from HIV virus to separate out HIV proteins (antigens)
Indirect immunofluorescence: detects both virus and antibody to it
PCR: looks for HIV DNA in the WBCs of a person
Virus isolation: used to definitively diagnose HIV

Prevention and Treatment

Prevention: avoid sexual contact with infected individuals, avoid sharing needles/syringes, avoid contact with bodily fluids
New methods for prevention: intravaginal lime or lemon juice, intravaginal oestrogen, male circumcision, and post-coital penile hygiene
Treatment: anti-viral agents, Nucleoside Reverse Transcriptase inhibitors (e.g., AZT), Non-Nucleoside Transcriptase inhibitors (e.g., Viramune), and Protease inhibitors (e.g., Norvir)
Vaccine: currently, no vaccines are approved for use by the FDA; two types in development: therapeutic vaccine and preventive vaccine

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Description

This quiz covers the basic characteristics and structure of the Human Immunodeficiency Virus (HIV), including its morphology, replication, and effects on the immune system.