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Flashcards in WBCs Deck (43):

What is CCR5

A protein on the surface of white blood cells that is involved in the immune system (acts as a receptor for chemokines)


Many forms of HIV initially use what to enter and infect host cells



What is CXCR4

An alpha-chemokine receptor specific for stromal-derived-factor-1, a molecule endowed with potent chemotactic activity for lymphocytes.


This receptor is one of several chemokine receptors that HIV can use to infect CD4+ T cells. HIV isolates that use this receptor are traditionally known as T-cell tropic isolates. Typically, these viruses are found late in infection. It is unclear as to whether the emergence of HIV that uses this receptor is a consequence or a cause of immunodeficiency.



What is CD4

A glycoprotein found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells.


The most common and pathogenic strain of the HIV

HIV-1 (class D retrovirus)


Form of HIV that has not been widely seen outside of Africa

HIV-2 (class D retrovirus)


A virus that has been implicated in several kinds of diseases including myelopathy, Strongyloides stercoralis hyper-infection, and a virus cancer link for leukemia

HTLV-1 (class C retrovirus)


Has not been clearly linked to any disease, but has been associated with several cases of myelopathy/tropical spastic paraparesis-like neurological disease.

HTLV-2 (class C retrovirus)



A component of the HIV particle capsid. There are approximately 2000 molecules per virus particle



A virus genome that is integrated into the DNA of a host cell


A large group or cloud of related genotypes that exist in an environment of high mutation rate, where a large fraction of offspring are expected to contain one or more mutations relative to the parent.



This is a part or region of the Human Immunodeficiency Virus that allows it to infect human immune cells by binding to a cytokine receptor on the target human immune cell (CCR5 cell or CXCR4 cell depending on the strain of HIV)

gp120 (V3 loop?)


Causes human T-cell leukemia/lymphoma (ATL) through infection and transformation of T lymphocytes.

HTLV -I (class C retrovirus)


MOA: HTLV -I (class C retrovirus)

Production of viral protein (TAX) which increases transcription from viral promoter (LTR) as well as from some cellular genes


Transmission: sexual, contaminated blood products and maternal-fetal (perinatal; breast milk). latent period of at least 30 years.

HTLV -I (class C retrovirus)


A shorter more aggressive clinical course. high white blood cell counts with malignant appearing cells, frequent skin lesions, hepatosplenomegaly, lymphadenopathy, lytic bone lesions. Caused by HTLV -I

Acute Adult T-cell Lymphoma (ATL)


Tropical Spastic Paraparesis (HTLV associated myelopathy)

Progressive destruction in spinal cord. Pathogenesis believed to be associated with chronic inflammatory response


Insidious onset usually in males > 50 years; prognosis of 3-5 years; infiltration of bone marrow and spleen by disease-specific cells of either T or B cell origin. Patients have severe pancytopenia, massive splenomegaly, and infections; death related to infection or consequences of organ infiltration.

Hairy-cell leukemia


Hairy-cell leukemia has equivocal ties to what

HTLV-2 (class C retrovirus)


Transmission: HIV

Primarily through internal exposure to body fluids or secretions carrying released virus or cell-associated virus. High risk fluids include semen and vaginal/cervical secretions, blood, plasma/serum, breast milk. may take between 1-2 weeks to establishinfection


T-helper lymphocytes that become infected with virus will support virus replication and will be lysed. Monocytes/macrophages, Langerhans cells, dendritic follicle cells will take up virus. Not all strains of virus will replicate in these cells. Cells that don't support viral replication may act as reservoirs and disseminate the virus.

HIV (class D retrovirus)


Infected can develop ATL (1-4% of infected) or HAM/TSP (1-4% of infected). May also be associated with immunosuppression during co-infection with S. stercoralis

HTLV-1 (class C retrovirus)


Usually very long incubation time until disease. Transformed CD4+, CD8- T-cells predominantly. Also transforms B cell and bone marrow precursors. Acute onset is more severe. Risk is higher in men

Adult T-cell leukemia/lymphoma (ATL)


Incidence is higher in women. Onset around 40 yrs from exposure to disease. Progressive degeneration of spinal cord (T region). Faster progression to paralysis in older people. Disease may be immune-mediated. Caused by HTLV-1

Tropical Spastic Paraparesis (HTLV associated myelopathy)


What binds CD4, triggering a conformational change that draws the HIV virus closer to the surface of the cell

Gp120 (V3 loop?)


Once gp120 has bound CD4, what binds to CCR5 or CXCR4 to facilitate HIV entry into the cell

Again Gp120 (V3 loop?)


What facilitates fusion of the HIV virus and the cell

The peptide portion of the gp41 stalk


In order for HIV to gain entry to a cell, what must be on that cell's surface

CD4 and a co-receptor (CCR5 or CXCR4)


CCR5 is commonly found on what cells

Cells with a macrophage or dendritic origin and usually found on mucosal surfaces


CXCR4 is commonly found on what cells



Which HIV virus will infect CD4-CCR5 cells

M-tropic virus


Which HIV virus will infect CD4-CXCR4 cells

T-tropic virus


Acute stage HIV infection

Rash. Peak virus replication. Establishment of reservoirs (first reservoir is gut lymphoid tissue)


Intermediate stage HIV infection

8-9 yr period. Low levels of virus replication. Known as clinical latency


Late stage HIV infection

When most people get diagnosed. Severe drop in CD4 count


Infected individual carries many variants of virus because

HIV reverse transcriptase is very error prone


What 2 key proteins are found on the surface of HIV

The fusion protein gp41 (transmembrane component) and surface attachment protein gp120 (extracellular component) are located on the HIV envelope.


What is P17

The HIV matrix protein


What is p24

The HIV capsid protein


What is located inside the capsid of the HIV virus

2 identical RNA copies of the genome with nucleocapsid proteins attached


Type D viruses

Have a cone shaped capsid/core structure (HIV-1&2)


Type C viruses

Have a hexagonal capsid/core structure (HTLV-1&2)