Ch. 54- Retroviruses: HIV

Flashcards covering key vocabulary related to HIV, its biology, infection cycle, disease progression, treatment options, and prevention strategies based on the provided lecture notes.

Human Immunodeficiency Virus (HIV)

A retrovirus that causes acquired immunodeficiency syndrome (AIDS), characterized by the progressive failure of the immune system.

Retrovirus

A family of RNA viruses, including HIV, that use reverse transcriptase to convert their RNA genome into DNA, which integrates into the host cell chromosome.

Pneumocystis carinii pneumonia (PCP)

An opportunistic infection, almost exclusively limited to severely immunosuppressed patients, commonly seen in early observed AIDS cases.

Cellular-immune dysfunction

An impairment of the cell-mediated immune system, suggested in early HIV cases as predisposing individuals to opportunistic infections.

Lentivirus

A genus of retroviruses, characterized by a long incubation period, which includes HIV.

Reverse transcription

The process by which an RNA virus converts its RNA genome into a DNA provirus using a viral enzyme called reverse transcriptase.

DNA provirus

A DNA copy of an RNA retroviral genome that has integrated into the host cell's chromosome.

HIV-1

The most common and virulent type of Human Immunodeficiency Virus, related to chimpanzee strains (SIVcpz).

HIV-2

A less virulent type of Human Immunodeficiency Virus, derived from sooty mangabey strains (SIVSM).

Hunter Theory (HIV Origin)

The most commonly accepted hypothesis that HIV is a viral zoonosis, originating from SIVcpz in chimpanzees transmitted to humans through bushmeat.

Viral zoonosis

A disease caused by a virus that crosses the species barrier from animals to humans.

SIVcpz

Simian Immunodeficiency Virus that infects chimpanzees, considered the precursor to HIV-1.

SIVSM

Simian Immunodeficiency Virus that infects sooty mangabeys, considered the precursor to HIV-2.

HIV Mutation

The rapid change in HIV's genetic material, leading to high genetic variation, quasispecies, drug resistance, and immune evasion.

HIV-1 M (Major) group

The predominant group of HIV-1, responsible for the global pandemic, further divided into clades or subtypes.

HIV Clades/Subtypes

Genetic variations within the HIV-1 M group, designated A, B, C, D, F, G, H, and K.

HIV Virion

The complete, infectious HIV particle, consisting of an RNA genome, enzymes, capsid, and an outer envelope with glycoproteins.

gp120 (SU glycoprotein)

The outer envelope glycoprotein of HIV, responsible for binding to the CD4 receptor and chemokine co-receptors on host cells.

gp41 (TM glycoprotein)

The transmembrane envelope glycoprotein of HIV, responsible for mediating fusion of the viral and host cell membranes.

Reverse Transcriptase (pol)

A viral enzyme encoded by the pol gene that converts the single-stranded RNA genome into double-stranded DNA.

Integrase (int)

A viral enzyme encoded by the pol gene that inserts the viral DNA (provirus) into the host cell's chromosomal DNA.

Protease (pro)

A viral enzyme encoded by the pol gene that cleaves viral polyproteins into individual functional proteins during virus maturation.

gag gene

An essential HIV gene that encodes group-specific antigen proteins, including the core and capsid proteins (e.g., p17, p24, p7, p9).

pol gene

An essential HIV gene that encodes the polymerase enzymes: reverse transcriptase, protease, and integrase.

env gene

An essential HIV gene that encodes the envelope glycoproteins gp120 and gp41.

Regulatory genes (HIV)

HIV genes (e.g., tat, rev, nef, vif, vpr, vpu) that regulate viral replication, increase virulence, and counteract cellular defense mechanisms.

Perinatal transmission (HIV)

The transmission of HIV from mother to child during pregnancy, childbirth, or breastfeeding.

CD4 receptor

A protein on the surface of immune cells (e.g., T-helper cells) that HIV's gp120 binds to, initiating viral entry.

Chemokine co-receptor (HIV)

Secondary receptors on host cells, such as CCR5 or CXCR4, that HIV uses for entry after binding to CD4.

CCR5

A chemokine co-receptor used by most HIV strains (R5 viruses) for entry into host cells, particularly during initial infection.

HIV-cell membrane fusion

The process mediated by gp41 where the HIV envelope merges with the host cell membrane, allowing the viral core to enter the cell.

Proviral DNA integration

The irreversible step where HIV's DNA copy becomes a permanent part of the host cell's chromosomal DNA.

Budding (HIV)

The process by which newly assembled HIV virions exit the host cell, acquiring an envelope derived from the cell membrane.

Maturation (HIV)

The final stage of the HIV replication cycle where the viral protease cleaves polyproteins, leading to functional proteins and an infectious virion.

Acute HIV Syndrome (ARS) / Primary HIV infection

The initial stage of HIV infection, occurring 2-4 weeks post-exposure, often accompanied by flu-like symptoms and large viremia.

Clinical Latency (HIV)

A stage of HIV infection where the virus is active but reproduces at low levels, and the infected person typically does not experience symptoms.

Opportunistic infections (HIV)

Infections caused by pathogens that take advantage of a weakened immune system, common in individuals with advanced HIV infection.

CD4 T-cell count

A measure of the number of CD4+ T lymphocytes in the blood, used to monitor immune system health and HIV progression.

Viral Load (HIV)

The amount of HIV RNA or DNA in the blood, indicating the level of viral replication, used to monitor infection and treatment effectiveness.

p24 (HIV antigen)

A protein specific to the HIV capsid, detectable in the blood during acute infection and used as a marker for viral presence.

Quasispecies (HIV)

A population of closely related but genetically distinct HIV variants within a single infected individual, due to high mutation rates.

Escape mutants (HIV)

HIV variants that develop mutations allowing them to evade detection and destruction by the host's immune response or antiretroviral drugs.

Early symptomatic chronic HIV infection (ARC)

A stage of HIV infection characterized by nonspecific symptoms like low-grade fever, fatigue, and weight loss, with CD4+ T cell counts typically >200/µL.

Oral hairy leukoplakia

A non-AIDS defining condition often seen in early symptomatic HIV, characterized by white, hair-like lesions on the tongue.

AIDS (Acquired Immunodeficiency Syndrome)

The final and most severe stage of HIV infection, defined by CD4+ T-cell counts below 200 cells/µL or the presence of specific AIDS-defining illnesses.

AIDS-defining illnesses

Severe opportunistic infections or cancers (e.g., Kaposi's sarcoma, Pneumocystis pneumonia, CMV retinitis) characteristic of advanced HIV infection.

Kaposi's sarcoma

A type of cancer that forms lesions on the skin, lymph nodes, and internal organs, an AIDS-defining illness.

HIV-associated neurocognitive disorder (HAND)

A spectrum of mild to severe neurocognitive impairments seen in HIV-infected individuals when HIV is present in the CNS.

HIV-associated dementia (HAD)

The most severe form of HAND, characterized by significant cognitive, motor, and behavioral impairments, an AIDS-defining illness.

Microglial cells (HIV reservoir)

Immune cells of the central nervous system that can serve as an important reservoir for HIV in the brain.

Long-Term Nonprogressors (LTNPs) / Elite Controllers

Individuals infected with HIV who maintain high CD4 T-cell counts and low or undetectable viral loads for many years without antiretroviral therapy.

CCR5-delta 32 mutation

A genetic mutation in the CCR5 gene that prevents the expression of a functional CCR5 co-receptor, conferring resistance or slower progression to R5 HIV.

Antiretroviral Therapy (ART)

The use of a combination of at least three antiretroviral drugs to suppress HIV replication, reduce viral load, and improve immune function.

Zidovudine (AZT)

The first approved HIV-1 treatment, a nucleoside reverse transcriptase inhibitor (NRTI).

RT inhibitor (Reverse Transcriptase Inhibitor)

A class of antiretroviral drugs that block the activity of HIV's reverse transcriptase enzyme, preventing viral RNA from becoming DNA.

Protease inhibitors (PIs)

A class of ART drugs that block the HIV protease enzyme, preventing the cleavage of viral polyproteins and the production of mature, infectious virions.

Fusion inhibitors

A class of ART drugs that prevent HIV from fusing with and entering host cells by interfering with gp41.

Integrase inhibitors

A class of ART drugs that block the HIV integrase enzyme, preventing the integration of viral DNA into the host cell's genome.

Pre-exposure prophylaxis (PrEP)

Antiviral medication (e.g., Truvada, Lenacapavir) taken consistently before potential exposure to HIV to prevent infection in high-risk individuals.

Post-exposure prophylaxis (PEP)

Antiviral medication taken after potential exposure to HIV, typically within 72 hours, to prevent infection.